Back in early May, I interviewed experts on dispersants and oil spill clean up and wrote “Out of Sight: BP’s dispersants are toxic — but not as toxic as dispersed oil.”

Chemically dispersing oil spills “solves the political problem of visible oil but not the environmental problem,” Robert Brulle, a 20-year Coast Guard veteran and an affiliate professor of public health at Drexel University, told me. These dispersants “do not actually reduce the total amount of oil entering the environment,” as a 2005 National Academy of Sciences report on the subject put it.  Nobody has any idea what will be the impact of massive exposure to these toxic chemicals on organisms that live on the bottom or feed off the bottom of the ocean.

In short: out of sight, out of mind. But not out of the body of marine life.

The dispersants seem to have done their job — and keeping oil off sensitive coastal habitats is a very good thing.  But some in the media seem to have confused not seeing oil with not being harmed by it.

In fact, as Science reports, “Oil Contamination of Crab Larvae Could Be Widespread“:

Researchers have found droplets of oil inside crab larvae in the Gulf of Mexico. Although preliminary, the findings represent the first sign of hydrocarbons from the Deepwater Horizon well entering the food web.

Wonk Room’s Brad Johnson has more on the premature declaration of “Mission Accomplished”:

In a contrarian take today, Time Magazine’s Michael Grunwald wrote a preemptive post-mortem impact of BP’s Deepwater Horizon disaster, saying that it “does not seem to be inflicting severe environmental damage. Grunwald believes that Rush Limbaugh “has a point” because the right-wing radio host spent weeks dismissing the disaster. New York Times reporters Justin Gillis and Campbell Robertson wrote that the “oil slick in the Gulf of Mexico appears to be dissolving far more rapidly than anyone expected.” The Associated Press’s John Carey believes “the oil slicks that once spread across thousands of miles of the Gulf of Mexico have largely disappeared.” The narrative of the disappearing disaster has been promoted by Politico’s Mike Allen and the Drudge Report.

Meanwhile, the oil blowout has been contained but not killed, oil continues to wash ashore, and the haphazard scientific effort to understand the 100-day disaster is hobbled by BP’s interference and governmental lassitude. It’s fair to point out, as Grunwald does, that the oil disaster’s impact on Louisiana’s shoreline is likely to be meaningless if the marshlands continue to disappear. Fringe rumors of global eco-collapse — never promoted by major environmental groups — continue to be as baseless as the nonsense spouted by conservative activists, media, and politicians on behalf of the oil industry.

However, the only honest take on the BP disaster right now is that this is a calamity, the true scope of which will take years to discover, with many impacts impossible to ever know. No one knows how badly this disaster will affect the dying marshlands of Louisiana. No one knows how badly the toxic oil plumes will affect the spawning grounds of the bluefin tuna, the feeding grounds of the threatened Gulf sturgeon, or the future of the endangered Kemp’s ridley sea turtles, whose corpses have been found at 15 times the historical rate this summer. No one knows what the long-term physical and mental health impacts will be on the tens of thousands of cleanup workers.

Moreover, it is undoubtedly premature to announce that the vast oil slick has largely disappeared from the ocean’s surface. Thick oil, vast slicks, and tar balls continue to wash ashore along Louisiana’s coastline. Satellite imagery from July 27 and 28 — as the stories of disappearing oil were being filed — show a vast region still discolored by slicks and sheen, little diminished from previous weeks:

At the Gulf Restoration Network, Matthew Preusch reports that scientists like George Crozier, executive director of the University of South Alabama’s Dauphin Island Sea Lab, are deeply concerned about the undersea dispersed oil:

“A lot of our eggs and larvae are in the top 100 meters, so as this cloud of toxins spreads upward, we’re making an assumption that its killing all of them,” he said. “I absolutely hate the use of dispersants at depth. I think that was the most huge of mistake in the process of containment.”  Last week, a group of prominent marine researchers released a statement calling for the end of the use of dispersants in the Gulf, saying, “Corexit dispersants, in combination with crude oil, pose grave health risks to marine life and human health.”

This article was originally posted on Climate Progress

In this paper, Broecker correctly predicted “that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide”, and that “by early in the next century [carbon dioxide] will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years”. He predicted an overall 20th Century global warming of 0.8ºC due to CO₂ and worried about the consequences for agriculture and sea level.


Global temperature up to June 2010 according to the NASA GISS data. Grey line is the 12-month running average, red dots are annual-mean values. The thick red line is a non-linear trend line. Broecker of course did not have these data available, not even up to 1975, since this global compilation was only put together in the late 1970s (Hansen et al. 1981). He had to rely on more limited meteorological data.

To those who even today claim that global warming is not predictable, the anniversary of Broecker’s paper is a reminder that global warming was actually predicted before it became evident in the global temperature records over a decade later (when Jim Hansen in 1988 famously stated that “global warming is here”).

Broecker is one of the great climatologists of the 20th Century: few would match his record of 400 scientific papers, a full sixty of which have over 100 citations each! Interestingly, his “global warming” paper is not amongst those highly-cited ones, with “only” 79 citations to date. Broecker is most famous for his extensive work on paleoclimate and ocean geochemistry.

It is very instructive to see how Broecker arrived at his predictions back in 1975 – not least because even today, many lay people incorrectly assume that we attribute global warming to CO₂ basically because temperature and CO₂ levels have both gone up and thus correlate. Broecker came to his prediction at a time when CO₂ had been going up but temperatures had been going down for decades – but Broecker (like most other climate scientists at the time, and today) understood the basic physics of the issue.

Basically his prediction involved just three simple steps that in essence are still used today.

Step 1: Predict future emissions

Broecker simply assumed a growth in fossil fuel CO₂ emissions of 3% per year from 1975 onwards. With that, he arrived at cumulative fossil CO₂ emissions of 1.67 trillion tons by the year 2010 (see his Table 1). Not bad: the actual emissions turned out to be about 1.3 trillion tons (Canadell et al, PNAS 2007 – estimate extended to 2010 by me).

A shortcoming, from the modern point of view, is that Broecker did not include other anthropogenic greenhouse gases or aerosol particles in his calculations. He does however discuss aerosols, which he calls “dust”. In fact, the first sentence of the abstract (quoted above) in full starts with an if-statement:

If man-made dust is unimportant as a major cause of climate change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide.

That is a nod to the discussion about aerosol-induced cooling in the early 1970s. Broecker rightly writes:

It is difficult to determine the significance of the next most important climatic effect induced by man, “dust”, because of uncertainties with regard to the amount, the optical properties and the distribution of man-made particles,

citing a number of papers by Steve Schneider and others. Because he cannot quantify it, he leaves out this effect. Here luck was on Broecker’s side: the warming by other greenhouse gases and the cooling by aerosols largely cancel today, so considering only CO₂ leads to almost the same radiative forcing as considering all anthropogenic effects on climate (see IPCC AR4, Fig. SPM.2).

Table 1 of Broecker (1975)

Step 2: Predict future concentrations

To go from the amount of CO₂ emitted to the actual increase in the atmosphere, one needs to know what fraction of the emissions remains in the air: the “airborne fraction”. Broecker simply assumed, based on past data of emissions and CO₂ concentrations (Keeling’s Mauna Loa curve), that the airborne fraction is a constant 50%. I.e., about half of our fossil fuel emissions accumulates in the atmosphere. That is still a good assumption today, if you look at the observed CO₂ increase as fraction of fossil fuel emissions. Broecker calculated that about 35% of the emissions is taken up by the ocean and the other 15% by the biosphere (again not far from modern values, see Canadell et al.). On this basis he argued that if the ocean is the main sink, the airborne fraction would remain almost constant for the decades to come (his calculations extend to the year 2010).

Thus, with a 3% increase in emissions per year and 50% of that remaining airborne, it is easy to compute the increase in CO₂ concentrations. He obtains an increase from 295 to 403 ppm from 1900 to 2010. The actual value in 2010 is 390 ppm, a little lower than Broecker estimated because his forecast cumulative emissions were a little too high.

Step 3: Compute the global temperature response

Now we come to the temperature response to increased CO₂ concentration. Broecker writes:

The response of the global temperature to the atmospheric CO₂ content is not linear. As the CO₂ content of the atmosphere rises, the absorption of infrared radiation will “saturate” over an ever greater portion of the band. Rasool and Schneider point out that the temperature increases as the logarithm of the atmospheric CO2 concentration.

Based on this logarithmic relationship (still valid today) Broecker assumes a climate sensitivity of 0.3ºC warming for each 10% increase in CO2 concentration, which amounts to 2.2ºC warming for CO₂ doubling. This is based on early calculations by Manabe and Wetherald. Broecker writes:

Although surprises may yet be in store for us when larger computers and better knowledge of cloud physics allow the next stage of modeling to be accomplished, the magnitude of the CO₂ effect has probably been pinned down to within a factor of 2 to 4.

The AR4 gives the uncertainty range of climate sensitivity as 2-4.5ºC warming for CO₂ doubling, so there still is about a factor of 2 uncertainty and Broecker used a value near the very low end of this uncertainty range. Modern estimates are not only based on model calculations but also on paleoclimatic and modern data; the AR4 lists 13 studies that constrain climate sensitivity in its table 9.3.

In Broecker’s paper the warming calculated with the help of climate sensitivity happens instantaneously. Today we know that the climate system responds with a time lag due to ocean thermal inertia. By neglecting this, Broecker overestimated the warming at any given time; accounting for thermal inertia would have reduced his warming estimate by about a third (see AR4 Fig. SPM.5). But again he was lucky: picking ~2ºC rather than the more likely ~3ºC climate sensitivity compensates roughly for this, so his 20th-Century warming of 0.8ºC is almost spot on (the actual estimate being closer to 0.7ºC, see Fig. above). (A modern version of this back-of-envelope warming calculation is found e.g. in our book Our Threatened Oceans, p.82.)

Natural Variability

Broecker was not the first to predict CO₂-induced warming. In 1965, an expert report to US President Lyndon B. Johnson had warned: “By the year 2000, the increase in carbon dioxide will be close to 25%. This may be sufficient to produce measurable and perhaps marked changes in climate.” And in 1972, a more specific prediction similar to Broecker’s was published by the eminent atmospheric scientist J.S. Sawyer in Nature (for a history in a nutshell, see my newspaper column here).

The innovation of Broecker’s article – apart from introducing the term “global warming” – was in combining estimates of CO₂ warming with natural variability. His main thesis was that a natural climatic cooling

has, over the last three decades, more than compensated for the warming effect produced by the CO₂ [....] The present natural cooling will, however, bottom out during the next decade or so. Once this happens, the CO₂ effect will tend to become a significant factor and by the first decade of the next century we may experience global temperatures warmer than any in the last 1000 years.

The latter turned out to be correct. The idea that the small cooling from the 1940s to 1970s is due to natural variability still cannot be ruled out, although more likely this is a smaller part of the explanation and the cooling is primarily due to the “dust” neglected by Broecker, i.e. due to the rise of anthropogenic aerosol pollution (Taylor and Penner, 1994). However, the way Broecker estimated and even predicted natural variability has not stood the test of time. He used data from the Camp Century ice core in Greenland, arguing that these “may give a picture of the natural fluctuations in global temperature over the last 1000 years”. Ironically, Broecker’s own later work on Atlantic ocean circulation changes showed that Greenland is likely even less representative of global temperature changes than most other places on Earth, it being strongly affected by variability in ocean heat transport (see our recent post on the Younger Dryas, or Broecker’s latest book The Great Ocean Conveyor). However, Broecker was right to conclude that the buildup of CO₂ would sooner or later overwhelm such natural climate variations.

Overall, Broecker’s paper (together with that of Sawyer) shows that valid predictions of global warming were published in the 1970s in the top journals Science and Nature, and warming has been proceeding almost exactly as predicted for at least 35 years now. Some important aspects were not understood back then, like the role of greenhouse gases other than CO₂, of aerosol particles and of ocean heat storage. That the predictions were almost spot-on involved an element of luck, since the neglected processes do not all affect the result in the same direction but partly cancel. Nevertheless, the basic fact that rising CO₂ would cause a “pronounced global warming”, as Broecker put it, was well understood in the 1970s. In a 1979 TV interview, Steve Schneider rightly described this as a consensus amongst experts, with controversy remaining about the exact magnitude and effects.

Reference
BROECKER WS, 1975: CLIMATIC CHANGE – ARE WE ON BRINK OF A PRONOUNCED GLOBAL WARMING?
SCIENCE Volume 189, Pages 460-463.

This article was originally posted on Real Climate

If you don’t know much about climate science, or about the details of the controversy over the “hockey stick,” then A. W. Montford’s book The Hockey Stick Illusion: Climategate and the Corruption of Science might persuade you that not only the hockey stick, but all of modern climate science, is a fraud perpetrated by a massive conspiracy of climate scientists and politicians, in order to guarantee an unending supply of research funding and political power. That idea gets planted early, in the 6th paragraph of chapter 1.

The chief focus is the original hockey stick, a reconstruction of past temperature for the northern hemisphere covering the last 600 years by Mike Mann, Ray Bradley, and Malcolm Hughes (1998, Nature, 392, 779, doi:10.1038/33859, available here), hereafter called “MBH98″ (the reconstruction was later extended back to a thousand years by Mann et al, 1999, or “MBH99″ ). The reconstruction was based on proxy data, most of which are not direct temperature measurements but may be indicative of temperature. To piece together past temperature, MBH98 estimated the relationships between the proxies and observed temperatures in the 20th century, checked the validity of the relationships using observed temperatures in the latter half of the 19th century, then used the relationships to estimate temperatures as far back as 1400. The reconstruction all the way back to the year 1400 used 22 proxy data series, although some of the 22 were combinations of larger numbers of proxy series by a method known as “principal components analysis” (hereafter called “PCA”–see here). For later centuries, even more proxy series were used. The result was that temperatures had risen rapidly in the 20th century compared to the preceding 5 centuries. The sharp “blade” of 20th-century rise compared to the flat “handle” of the 15-19th centuries was reminiscent of a “hockey stick” — giving rise to the name describing temperature history.

But if you do know something about climate science and the politically motivated controversy around it, you might be able to see that reality is the opposite of the way Montford paints it. In fact Montford goes so far over the top that if you’re a knowledgeable and thoughtful reader, it eventually dawns on you that the real goal of those whose story Montford tells is not to understand past climate, it’s to destroy the hockey stick by any means necessary.

Montford’s hero is Steve McIntyre, portrayed as a tireless, selfless, unimpeachable seeker of truth whose only character flaw is that he’s just too polite. McIntyre, so the story goes, is looking for answers from only the purest motives but uncovers a web of deceit designed to affirm foregone conclusions whether they’re so or not — that humankind is creating dangerous climate change, the likes of which hasn’t been seen for at least a thousand or two years. McIntyre and his collaborator Ross McKitrick made it their mission to get rid of anything resembling a hockey stick in the MBH98 (and any other) reconstruction of past temperature.

Principal Components

For instance: one of the proxy series used as far back as the year 1400 was NOAMERPC1, the 1st “principal component” (PC1) used to represent patterns in a series of 70 tree-ring data sets from North America; this proxy series strongly resembles a hockey stick. McIntyre & McKitrick (hereafter called “MM”) claimed that the PCA used by MBH98 wasn’t valid because they had used a different “centering” convention than is customary. It’s customary to subtract the average value from each data series as the first step of computing PCA, but MBH98 had subtracted the average value during the 20th century. When MM applied PCA to the North American tree-ring series but centered the data in the usual way, then retained 2 PC series just as MBH98 had, lo and behold — the hockey-stick-shaped PC wasn’t among them! One hockey stick gone.

Or so they claimed. In fact the hockey-stick shaped PC was still there, but it was no longer the strongest PC (PC1), it was now only 4th-strongest (PC4). This raises the question, how many PCs should be included from such an analysis? MBH98 had originally included two PC series from this analysis because that’s the number indicated by a standard “selection rule” for PC analysis (read about it here).

MM used the standard centering convention, but applied no selection rule — they just imitated MBH98 by including 2 PC series, and since the hockey stick wasn’t one of those 2, that was good enough for them. But applying the standard selection rules to the PCA analysis of MM indicates that you should include five PC series, and the hockey-stick shaped PC is among them (at #4). Whether you use the MBH98 non-standard centering, or standard centering, the hockey-stick shaped PC must still be included in the analysis.

It was also pointed out (by Peter Huybers) that MM hadn’t applied “standard” PCA either. They used a standard centering but hadn’t normalized the data series. The 2 PC series that were #1 and #2 in the analysis of MBH98 became #2 and #1 with normalized PCA, and both should unquestionably be included by standard selection rules. Again, whether you use MBH non-standard centering, MM standard centering without normalization, or fully “standard” centering and normalization, the hockey-stick shaped PC must still be included in the analysis.

In reply, MM complained that the MBH98 PC1 (the hockey-stick shaped one) wasn’t PC1 in the completely standard analysis, that normalization wasn’t required for the analysis, and that “Preisendorfer’s rule N” (the selection rule used by MBH98) wasn’t the “industry standard” MBH claimed it to be. Montford even goes so far as to rattle off a list of potential selection rules referred to in the scientific literature, to give the impression that the MBH98 choice isn’t “automatic,” but the salient point which emerges from such a list is that MM never used any selection rules — at least, none that are published in the literature.

The truth is that whichever version of PCA you use, the hockey-stick shaped PC is one of the statistically significant patterns. There’s a reason for that: the hockey-stick shaped pattern is in the data, and it’s not just noise it’s signal. Montford’s book makes it obvious that MM actually do have a selection rule of their own devising: if it looks like a hockey stick, get rid of it.

The PCA dispute is a prime example of a recurring McIntyre/Montford theme: that the hockey stick depends critically on some element or factor, and when that’s taken away the whole structure collapses. The implication that the hockey stick depends on the centering convention used in the MBH98 PCA analysis makes a very persuasive “Aha — gotcha!” argument. Too bad it’s just not true.

Different, yes. Completely, no.

As another example, Montford makes the claim that if you eliminate just two of the proxies used for the MBH98 reconstruction since 1400, the Stahle and NOAMER PC1 series, “you got a completely different result — the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening.” That argument is sure to sell to those who haven’t done so. But I have. I computed my own reconstructions by multiple regression, first using all 22 proxy series in the original MBH98 analysis, then excluding the Stahle and NOAMER PC1 series. Here’s the result with all 22 proxies (the thick line is a 10-year moving average):

Here it is with just 20 proxies:

Finally, here are the 10-year moving average for both cases, and for the instrumental record:

Certainly the result is different — how could it not be, using different data? — but calling it “completely different” is just plain wrong. Yes, the pre-20th century is warmer with the 15th century a wee bit warmer still — but again, how could it not be when eliminating two hand-picked proxy series for the sole purpose of denying the unprecedented nature of modern warming? Yet even allowing this cherry-picking of proxies is still not enough to accomplish McIntyre’s purpose; preceding centuries still don’t come close to the late-20th century warming. In spite of Montford’s claims, it’s still a hockey stick.

Beyond Reason

Another of McIntyre’s targets was the Gaspe series, referred to in the MBH98 data as “treeline-11.” It just might be the most hockey-stick shaped proxy of all. This particular series doesn’t extend all the way back to the year 1400, it doesn’t start until 1404, so MBH98 had extended the series back four years by persistence — taking the earliest value and repeating it for the preceding four years. This is not at all an unusual practice, and — let’s face facts folks — extending 4 years out of a nearly 600-year record on one out of 22 proxies isn’t going to change things much. But McIntyre objected that the entire Gaspe series had to be eliminated because it didn’t extend all the way back to 1400. This argument is downright ludicrous — what it really tells us is that McIntyre & McKitrick are less interested in reconstructing past temperature than in killing anything that looks like a hockey stick.

McIntyre also objected that other series had been filled in by persistence, not on the early end but on the late end, to bring them up to the year 1980 (the last year of the MBH98 reconstruction). Again, this is not a reasonable argument. Mann responded by simply computing the reconstruction you get if you start at 1404 and end at 1972 so you don’t have to do any infilling at all. The result: a hockey stick.

Again, we have another example of Montford implying that some single element is both faulty and crucial. Without nonstandard PCA the hockey stick falls apart! Without the Stahle and NOAMER PC1 data series the hockey stick falls apart! Without the Gaspe series the hockey stick falls apart! Without bristlecone pine tree rings the hockey stick falls apart! It’s all very persuasive, especially to the conspiracy-minded, but the truth is that the hockey stick depends on none of these elements. You get a hockey stick with standard PCA, in fact you get a hockey stick using no PCA at all. Remove the NOAMER PC1 and Stahle series, you’re left with a hockey stick. Remove the Gaspe series, it’s still a hockey stick.

As a great deal of other research has shown, you can even reconstruct past temperature without bristlecone pine tree rings, or without any tree ring data at all, resulting in: a hockey stick. It also shows, consistently, that nobody is trying to “get rid of the medieval warm period” or “flatten out the little ice age” since those are features of all reconstructions of the last 1000 to 2000 years. What paleoclimate researchers are trying to do is make objective estimates of how warm and how cold those past centuries were. The consistent answer is, not as warm as the last century and not nearly as warm as right now.

The hockey stick is so thoroughly imprinted on the actual data that what’s truly impressive is how many things you have to get rid of to eliminate it. There’s a scientific term for results which are so strong and so resistant to changes in data and methods: robust.

Cynical Indeed

Montford doesn’t just criticize hockey-stick shaped proxies, he bends over backwards to level every criticism conceivable. For instance, one of the proxy series was estimated summer temperature in central England taken from an earlier study by Bradley and Jones (1993, the Holocene, 3, 367-376). It’s true that a better choice for central England would have been the central England temperature time series (CETR), which is an instrumental record covering the full year rather than just summertime. The CETR also shows a stronger hockey-stick shape than the central England series used by MBH98, in part because it includes earlier data (from the late 17th century) than the Bradley and Jones dataset. Yet Montford sees fit to criticize their choice, saying “Cynical observers might, however, have noticed that the late seventeenth century numbers for CETR were distinctly cold, so the effect of this truncation may well have been to flatten out the little ice age.”

In effect, even when MBH98 used data which weakens the difference between modern warmth and preceding centuries, they’re criticized for it. Cynical indeed.

Face-Palm

The willingness of Montford and McIntyre to level any criticism which might discredit the hockey stick just might reach is zenith in a criticism which Montford repeats, but is so nonsensical that one can hardly resist the proverbial “face-palm.” Montford more than once complains that hockey-stick shaped proxies dominate climate reconstructions — unfairly, he implies — because they correlate well to temperature.

Duh.

Guilty

Criticism of MBH98 isn’t restricted to claims of incorrect data and analysis, Montford and McIntyre also see deliberate deception everywhere they look. This is almost comically illustrated by Montford’s comments about an email from Malcolm Hughes to Mike Mann (emphasis added by Montford):

Mike — the only one of the new S.American chronologies I just sent you that already appears in the ITRDB sets you already have is [ARGE030]. You should remove this from the two ITRDB data sets, as the new version should be different (and better for our purposes).
Cheers,
Malcolm

Here’s what Montford has to say:

It was possible that there was an innocent explanation for the use of the expression “better for our purposes”, but McIntyre can hardly be blamed for wondering exactly what “purposes” the Hockey Stick authors were pursuing. A cynic might be concerned that the phrase actually had something to do with “getting rid of the Medieval Warm Period”. And if Hughes meant “more reliable”, why hadn’t he just said so?

This is nothing more than quote-mining, in order to interpret an entirely innocent turn of phrase in the most nefarious way possible. It says a great deal more about the motives and honesty of Montford and McIntyre, than about Mann, Bradley, and Hughes. The idea that MM’s so-called “correction” of MBH98 “restored the MWP” constitutes a particularly popular meme in contrarian circles, despite the fact that it is quite self-evidently nonsense: MBH98 only went back to AD 1400, while the MWP, by nearly all definitions found in the professional literature, ended at least a century earlier! Such internal contradictions in logic appear to be no impediment, however, to Montford and his ilk.

Conspiracies Everywhere

Montford also goes to great lengths to accuse a host of researchers, bloggers, and others of attempting to suppress the truth and issue personal attacks on McIntyre. The “enemies list” includes RealClimate itself, claimed to be a politically motivated mouthpiece for “Environmental Media Services,” described as a “pivotal organization in the green movement” run by David Fenton, called “one of the most influential PR people of the 20th century.” Also implicated are William Connolley for criticizing McIntyre on sci.environment and James Annan for criticizing McIntyre and McKitrick. In a telling episode of conspiracy theorizing, we are told that their “ideas had been picked up and propagated across the left-wing blogosphere.” Further conspirators, we are informed, include Brad DeLong and Tim Lambert. And of course one mustn’t omit the principal voice of RealClimate, Gavin Schmidt.

Perhaps I should feel personally honored to be included on Montford’s list of co-conspirators, because yours truly is also mentioned. According to Montford’s typical sloppy research I have styled myself as “Mann’s Bulldog.” I’ve never done so, although I find such an appellation flattering; I just hope Jim Hansen doesn’t feel slighted by the mistaken reference.

The conspiracy doesn’t end with the hockey team, climate researchers, and bloggers. It includes the editorial staff of any journal which didn’t bend over to accommodate McIntyre, including Nature and GRL which are accused of interfering with, delaying, and obstructing McIntyre’s publications.

Spy Story

The book concludes with speculation about the underhanded meaning of the emails stolen from the Climate Research Unit (CRU) in the U.K. It’s really just the same quote-mining and misinterpretation we’ve heard from many quarters of the so-called “skeptics.” Although the book came out very shortly after the CRU hack, with hardly sufficient time to investigate the truth, the temptation to use the emails for propaganda purposes was irresistible. Montford indulges in every damning speculation he can get his hands on.

Since that time, investigation has been conducted, both into the conduct of the researchers at CRU (especially Phil Jones) and Mike Mann (the leader of the “hockey team”). Certainly some unkind words were said in private emails, but the result of both investigations is clear: climate researchers have been cleared of any wrongdoing in their research and scientific conduct. Thank goodness some of those who bought in to the false accusations, like Andy Revkin and George Monbiot, have seen fit actually to apologize for doing so. Perhaps they realize that one can’t get at the truth simply by reading people’s private emails.

Montford certainly spins a tale of suspense, conflict, and lively action, intertwining conspiracy and covert skullduggery, politics and big money, into a narrative worthy of the best spy thrillers. I’m not qualified to compare Montford’s writing skill to that of such a widely-read author as, say, Michael Crichton, but I do know they share this in common: they’re both skilled fiction writers.

The only corruption of science in the “hockey stick” is in the minds of McIntyre and Montford. They were looking for corruption, and they found it. Someone looking for actual science would have found it as well.

This article was originally posted on Real Climate

It’s almost routine by now: Every summer, many of those interested in climate change check again and again the latest data on sea-ice evolution in the Arctic. Such data are for example available on a daily basis from the US National Snow and Ice Data Center. And again and again in early summer the question arises whether the most recent trend in sea-ice extent might lead to a new record minimum, with a sea-ice cover that will be smaller than that in the record summer of 2007.

However, before looking at the possible future evolution of Arctic sea ice in more detail, it might be a good idea to briefly re-capitulate some events of the previous winter, because some of those are quite relevant for the current state of the sea-ice cover. The winter 2009/2010 will be remembered by many people in Europe (and not only there) as particularly cold, with lots of snow and ice. Not least because of the sustained cold, some began to wonder if global warming indeed was real.

Such questioning of global warming based on a regional cold period of course neglects the crucial difference between weather and climate, with the former being the only thing that we as individuals will ever be able to experience first hand. A single regional cold spell has not a lot to do with climate – let alone with global climate. This becomes quite obvious if one instead considers the mean temperature of the entire globe during the last 12 months: this period was, according to the GISS data, the warmest 12-month period since the beginning of the records 130 years ago. Regarding sea ice, it was particularly important that temperatures in parts of the Arctic were well above average for most of the winter. This was directly experienced by some members of our working group during a field experiment at the West Coast of Greenland.

The initial plan of this field experiment was to study the growth and decay of sea ice in great detail throughout an entire winter. In particular, we wanted to focus on the evolution of very young sea ice that had just formed from open water. Therefore, we wanted to start our measurements just before initial ice formation, which usually takes place in mid-November, at least according to past experience of the local Greenlandic population. Hence, we traveled to our measuring site close to the Greenlandic settlement of Upernavik in early November to put out our measuring buoys. We were hoping that ice formation would start shortly after we had put out the instruments such that they were protected from storms and waves. However, with temperatures that were often more than 10°C above the long-term mean, sea ice was nowhere to be seen. Even in January, there were days on end with above 0°C temperature and heavy rain fall. Finally, in February a stable ice cover formed, which of course remained relatively thin and which hence had melted completely by mid May.

The fact that it was sometimes warmer at our measurement site at the West Coast of Greenland than it was in Central Europe at the same time surprised us quite a bit. However, some recent studies indicate that such a distribution of relatively high temperature in parts of the Arctic and relatively low temperature in Northern and Central Europe and parts of the US might become somewhat more wide-spread in the future. While the Arctic has always shown large internal variability that lead to large-scale shifts in weather patterns, in the future the ongoing retreat of Arctic sea ice might cause those weather patterns to occur more often that allow for Northerly winds to bring cold air from the Arctic to the mid-latitudes. Hence, it is quite possible that because of the retreat of Arctic sea ice, some smaller parts of the Northern Hemisphere will experience pronounced cold spells during winter every now and then. The mean temperature of the Northern Hemisphere will nevertheless increase further, and the export of cold air from the Arctic of course leads to warm anomalies there.

But let’s return to the evolution of Arctic sea ice. Because of relatively high temperatures, Arctic sea-ice extent remained well below the long-term mean for most of the preceding winter. However, in March temperatures suddenly dropped for a couple of weeks, in particular in parts of the Barents Sea and in parts of the Beaufort Sea. This in turn lead to the formation of a thin ice cover in these regions, which caused a marked increase in observed sea-ice extent. For the measurement of this extent, it doesn’t matter at all how thick the ice is: any ice, however thin, contributes to sea-ice extent. Therefore, only considering a possible “recovery” of just the extent of Arctic sea ice always remains somewhat superficial, since sea-ice extent contains no information on the thickness of the ice. A much more useful measure for the state of Arctic sea ice is therefore the total sea-ice volume. However, for its estimation one additionally requires information on the overall distribution of ice thickness, which we have not been able to measure routinely in the past. While this will hopefully change in the future because of the successful launch of the Cryosat 2 satellite a couple of weeks ago, at the moment we unfortunately must rely on judging the current state of the Arctic sea-ice cover mostly by its extent.

Because of the very low thickness of much of the Arctic sea ice, it wasn’t too surprising that at the end of the winter, sea-ice extent decreased rapidly. This rapid loss lead up to the lowest June sea-ice extent since the beginning of reliable observations. After this rapid loss of the very thin ice that had formed late in winter, the retreat slowed down substantially but the ice extent remained well below the long-term mean. Currently, the ice covers an area that is slightly larger than the extent in late July of the record year 2007. However, this does not really allow for any reliable projections regarding the future evolution of Arctic sea ice in the weeks to come.

The reason for this is mostly that sea ice in the Arctic has become very thin. Hence, in contrast to the much thicker ice of past decades, the ice now reacts very quickly and very sensitively to the weather patterns that are predominant during a certain summer. This currently limits the predictability of sea-ice extent significantly. For example, in 2007 a relatively stable high-pressure system formed above the Beaufort sea, towards the north of North America, leading to rapid melting of sea ice there. If again such stable high pressure system forms in the Arctic throughout the coming weeks, we might well experience a sea-ice minimum that is below the record minimum as observed in 2007. However, if the summer should turn out to be colder than during the previous years, a sea-ice minimum similar to that observed in 2009 would not be too surprising. Hence, at the moment all that remains is to wait – and to check again and again the latest data of Arctic sea-ice extent.

Dirk Notz is head of the research group “Sea ice in the Earth System” at the Max-Planck-Institute for Meteorology in Hamburg.

The original version of this article was published in German at KlimaLounge

References:

Honda, M., J. Inoue, and S. Yamane (2009), Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters, Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079.

Notz, D. The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss. Proc. Nat. Ac. Sci. 106(49), 20590–20595, doi:10.1073/pnas.0902356106 (2009).

Polyakov, I. V., and M. A. Johnson (2000), Arctic decadal and interdecadal variability, Geophys. Res. Lett., 27(24), 4097–4100.

Credits:
Figure 1: NOAA ESRL Physics Science division

Figures 2-4: Data: NSIDC, Graphics: D. Notz.

This article was originally posted on Real Climate

The overbuilding of natural gas combined cycle plants starting in the mid-1990s presents a significant opportunity for near term reductions in CO2 emissions from the power sector. The current fleet of natural gas combined cycle (NGCC) units has an average capacity factor of 41 percent, relative to a design capacity factor of up to 85 percent. However, with no carbon constraints, coal generation is generally dispatched to meet demand before NGCC generation because of its lower fuel price.

Modeling of the ERCOT region (largely Texas) suggests that CO2 emissions could be reduced by as much as 22 percent with no additional capital investment and without impacting system reliability by requiring a dispatch order that favors NGCC generation over inefficient coal generation; preliminary modeling suggests that nationwide CO2 emissions [from the power sector] would be reduced by over 10 percent. At the same time, this would also reduce air pollutants such as oxides of sulfur and nitrogen.

That’s from the news release for the big MIT study, The Future of Natural Gas.

Considering that energy-related CO2 emissions are now down nearly 10% from 2005 levels, the point once again is that it is inexpensive and straightforward to reduce U.S. CO2 emissions to the 17% target for 2020 in most comprehensive climate bills — as I discussed over a year ago (see “Unconventional gas makes the 2020 climate targets so damn easy and cheap to meet“).  Meeting such a 17% target in the utility sector alone, as in the latest incarnation of the watered-down climate bill, would be utterly trivial.

CAP’s Susan Lyon (along with Joseph Romm) has more on the MIT Study, which finds that natural will play a “crucial role” over the next several decades in reducing carbon emissions and serve as a bridge fuel between a dirty fossil fuel past and a clean energy future — if we put a price on carbon.

Ernest J. Moniz, Director of the MIT Energy Initiative (MITEI), noted that the analysis determined that natural gas could serve as a bridge between coal and renewable energy:

Much has been said about natural gas as a bridge to a low-carton future, with little underlying analysis to back up this contention.  The analysis in this study provides the confirmation — natural gas truly is a bridge to a low-carbon future.

The study notes that the best way to spur this path forward is with a cap on carbon pollution.  It recommends that, “a CO2 price for all fuels without long-term subsidies or other preferential policy treatment is the most effective way to achieve this result.”

The 30-member study group modeled a variety of future policy scenarios.  They found that natural gas plays a significant role in cutting greenhouse gas emissions with major reductions coming from displacing inefficient, dirty coal-fired electric plants.

Furthermore, as U.S. natural gas markets are relatively mature compared to other countries, the U.S. is poised to be a leader in the coming push to expand natural gas markets globally.  Modeling shows that integrating the three global markets that currently exist – North America, Europe, and Asia – would significantly lower natural gas prices for American consumers.

Importantly, the study finds that “environmental issues associated with producing unconventional gas resources are manageable yet challenging.”  These environmental challenges, which have been heavily documented but are not yet thoroughly understood, stem primarily from the practice of hydraulic fracturing (‘fracking’) and the fracking fluids injected into the earth to access the gas itself.  These ‘manageable’ risks include surface water contamination, shallow freshwater aquifer contamination, pressure on local water supplies, and community disturbance due to drilling and fracking.  The study recommends, as CAP has, that companies should be required to disclose to government agencies and the public the chemicals used in hydraulic fracturing fluids.

The models, covering a variety of policy scenarios extending to 2050, find that natural gas consumption will dramatically increase and significantly displace coal — if there is a carbon price.  If not, “coal would continue to dominate.”

A scenario in which the U.S. does not restrict GHGs emission finds that U.S. gas production will rise by around 40% between 2009 and 2040.  If the U.S. puts a price on emissions, production will rise closer to 30% by 2040 but then start falling slowly.  In reality, even if we are dumb enough to not pass climate legislation in the next few years, it is certainly inevitable that we do so long before 2040, which makes projections beyond that point seem pointless.

The study finds that the natural gas resource base in the U.S. is large – enough for about 92 years worth of consumption at present domestic consumption rates – but much of this is from unconventional sources that will require additional research and development to recover.

To achieve an integrated role for natural gas in a carbon-constrained world, the study advocates several key policy recommendations.  Broadly, it argues, the U.S. should use more gas for electricity generation and transportation:

Results indicate that a coal to gas displacement strategy could reduce power sector CO2 emissions by about 22% and demand for natural gas in the ERCOT electricity generation market would increase (by 0.36 TcF/year).

The study also looks at using CNG to power light-duty vehicles and LNG for heavy-duty vehicles, respectively.  Because CNG use reduces GHG emissions by around 25% relative to gasoline, there could be a good passenger vehicle market; however, payback time of the upfront costs of a CNG conversion must become three years or less for market penetration to occur.  It also considers expanding the use of LNG for long-haul trucks, a currently limited market; CAP estimated that if we can get nearly 3 million natural gas heavy trucks on the road by 2035, they could eventually displace up to about 1 million barrels per day, or 45 percent of the projected oil consumption of heavy trucks by 2035.

Yet panelists at the study’s release were careful to note that great legislative uncertainty remains, in addition to other uncertain factors such as gas reserve size, cost structure, and market conditions.  In this uncertain climate, Gregory Staple, CEO of American Clean Skies Foundation, one of the study’s sponsors, argues for a strong natural gas title in energy legislation currently being debated in Congress, as well as stricter limits on global warming pollution:

At a minimum, a new energy bill should adopt stricter greenhouse gas emission standards for existing power plants and set a timetable for phasing out the least efficient and dirtiest coal-fired power plants.

Such a shift toward natural gas, under the right policies, can both enhance national security and reduce global warming pollution.  For natural gas to best transition into its role as bridge fuel, comprehensive clean energy and climate legislation should become a reality.

Related Posts:

• Game Changer, Part 1:  There appears to be a lot more natural gas than previously thought and
• 3:  Unconventional gas — great for low-cost climate action.
• 4:  Tim Wirth delivers must-read “extreme words” to natural gas execs: “You don’t have the right to sit back and do nothing” about climate change. “We are in very deep trouble, the edge of catastrophe, and you can help.”
• 5: RFK, Jr. on “How to end America’s deadly coal addiction … practically overnight” thanks to “a revolution in natural gas production”

This article was originally posted on Climate Progress

The long-awaited and surprisingly thorough Muir Russell report (readable online version) was released this morning. We’ve had a brief read through of the report, but a thorough analysis of this and the supplemental information on the web site will have to wait for a day or so.

The main issue is that they conclude that the rigour and honesty of the CRU scientists is not in doubt. For anyone who knows Phil Jones and his colleagues this comes as no surprise, and we are very pleased to have this proclaimed so vigorously. Secondly, they conclude that none of the emails cast doubt on the integrity and conclusions of the IPCC, again, something we have been saying since the beginning. They also conclude as we did that there was no ‘corruption’ of the peer-review process. Interestingly, they independently analysed the public domain temperature data themselves to ascertain whether the could validate the CRU record. They managed this in two days, somewhat undermining claims that the CRU temperature data was somehow manipulated inappropriately. (Note that this exercise has been undertaken by a number of people since November – all of which show that the CRU results are robust).

All in all, none of the various accusations and insinuations that have been floating around the blogosphere have been sustained. (See some of the early media coverage of the report).

However, there are two issues that have come up that deserve some comment. The first are the evolving practices of data presentation and access, and the second is the issue of how to handle Freedom of Information (FOI) requests.

As climate science has moved away from single researcher/single study/single site analyses towards synthesis across multiple studies, across the globe and involving more and more researchers, practices that were appropriate at one time don’t necessarily scale up to the new environment. Data requests dealt with on an ad-hoc and informal basis work fine if only a couple of people are interested, but more formal and automated procedures are needed when the data sets grow and many more people are involved (see the PCMDI/CMIP3 archive of model results for instance). Given too, the obsession in certain quarters with irrelevant details of smoothing techniques and end-point padding in decade-old papers, it is clear that the more information that is put out as supplementary material to the creation of high-profile figures, the better off we will be. Examples of this for figures in IPCC AR4 already exist, but it will be helpful for IPCC to adopt this practice more generally. Historically, this hasn’t been done – mainly because no-one thought it particularly interesting (most smoothing methods produce very similar results for instance), particularly for figures that weren’t for publication in the technical literature.

One example of this was the cover art on a WMO 1999 report which, until last November, was completely obscure (we are not aware of any mention of this report or this figure before November in any blogospheric discussion, ever). Nonetheless, in the way of these things, this figure is now described as ‘an icon’ in the Muir Russell report (one of their very few mistakes, how can something be an icon if no-one has ever seen it?). In retrospect (and as we stated last year) we agree with the Muir Russell report that the caption and description of the figure could indeed have been clearer, particularly with regard to the way proxy and instrumental data sources were spliced into a single curve, without indicating which was which. The WMO cover figure appears (at least to our knowledge) to be the only instance where that was done. Moving forward, nonetheless, it is advisable that scientists be as clear as possible about what sorts of procedures have gone into the preparation of a figure. But retrospective applications of evolving standards are neither fair nor useful.

With respect to the continuing barrage of FOI requests (which are predominantly for personal communications rather than for data), we can attest from personal experience how disconcerting these can be at first. Since there are no limits on what can be asked for (though there are many limits on what will be delivered), scientists presented with these requests often find them personally invasive and inappropriate. Institutions that do not have much experience with these kinds of requests, and who are not aware of what their employees do that is, and is not, covered by the legislation, are often not much help in sorting out how to respond. This can certainly be improved, as can the awareness of the community of what is recoverable using these procedures. While it is not relevant to the legislation, nor to what can be released, the obvious bad faith of many of the requesters indicates that actual information about the functioning of public bodies is not the primary goal in making these requests. However, it would be a terrible mistake for scientists to retreat from the public discussion on climate science because of these attempts at intimidation.

We will post on more specific aspects of the report, and perhaps the legacy of the whole affair over the next few days…

This article was originally posted on Real Climate

An anecdote is maybe relevant. I was on a panel with a long-time science writer from New York Times and we were discussing the information content in science columns versus sports columns (the latter having far more because the writers see no need to waste space to explain the rules, introduce the players, or even explicitly state what the actual sport is!). The NYT writer explained that she always pitched her stories at exactly the same level – (paraphrasing) the interested, but educated, person who did not need the details but wanted the big picture. Indeed, she went so far as to say that was the only relevant mode of public communication on science issues. I took issue with this (of course), because I think this ‘mainstream media’ mode of communication leaves a lot of people very unsatisfied and indeed, RealClimate is in part a response to that.

Both these examples suggest that there is a very widespread feeling that there is only one level at which public communications must be conducted (though people often disagree with what that is). But this is rather a pointless argument to be having. Particularly in the new landscape of disaggregated media, the idea that there is only one anything seems completely anachronistic. It might have been ok when the daily paper was the only information source that some people had and its audience could be assumed to be relatively homogeneous, but these things are certainly no longer true (if indeed they ever were).

Instead, I think we should be explicitly thinking about information levels and explicitly catering to different audiences with different needs and capabilities. One metaphor that might work well is that of an alpine ski hill. There we have (in the US for instance) green runs for beginners wanting a gentle introduction and where hopefully nothing too bad can happen. Blue runs where the technical level is a little more ambitious and a little more care needs to be taken. Black expert runs for those who know what they are doing and are doing it well, and finally, double black diamond runs for the true masters. No-one accuses ski resorts of being patronising when they have green runs interspersed with the more difficult ones, and neither do they get accused of elitism when one peak has only black runs going down (as I recall all too painfully on my first ski outing). People self-segregate and generally find their way to the level at which the feel comfortable – whether they want a easy or challenging ride – and there is nothing stopping them varying the levels as their mood or inclination takes them.

I think this is exactly what we need in science communication. Explanations and stories unapologetically pitched at all sorts of different levels (and not just at a fictional ‘Mr or Ms. Average Newspaper Reader’) actually already happens in many environments (though not in newspapers, TV or institutional websites), however, where the analogy breaks down is that there is no signage. There is no Google icon that tells you whether the link is a green level explanation or an experts-only-you-will-get-hurt-if-you-don’t-know-what-you-are-doing technical discussion. There is no Wikipedia sliding scale to direct you to the information level appropriate to your level of competence or background knowledge.

Thus we often find that beginners are confused or turned off by inappropriate (for them) complexity, and old hands demanding something more challenging, and people in the middle despairing that we aren’t reaching the ‘right’ people with whatever level we adopt.

So how should we move forward? Can we institute a some kind of information level meta-tagging that would eventually be recognised by Google? (does that even matter)? Does such a system exist already?

This article was originally posted on Real Climate

We’ve all seen pictures of the dreadful and continuing aftermath of the explosion on the Deepwater Horizon oil well in the Gulf of Mexico. The environmental cleanup and the economic consequences of this will last far into the future, and it’s hard to imagine that the time will come when fumes from oil, chemicals, and burning no longer pollute the air, oceans aren’t covered with sheets of oil, beaches aren’t stained with tar, and marshes aren’t clogged with residues. But with hard work that will eventually be the case. At that point the Unified Command—which was established under U.S. Coast Guard leadership to manage the response to this disaster—will fold, the cleanup workers will go home, and the raft of workers brought in from diverse agencies as part of the emergency response will be pulled back to deal with other more urgent tasks.

But health threats from the oil spill may linger unseen, perhaps for more than a generation. And we will not be fully prepared to address the public health problems that arise in the future unless there is an effective and coordinated handover of responsibilities for protecting public health from the emergency response agencies to agencies with the capability and capacity for long-term monitoring and management. Federal agencies have been pulled in as needed in the gulf spill response, but it’s not clear that the Health and Human Services response has been synchronized from the top to ensure effective delivery and coordination.

In short, the spill reiterates why we need to better manage the short- and longterm responses required to address the public health threats such disasters pose whether they are manmade or due to natural causes.

No systematic long-term monitoring and oversight was put in place with the Exxon Valdez spill in 1989, and now we wonder what we missed. Several studies following the Prestige oil spill off the coast of Spain in 2002 indicate that some respiratory problems in cleanup workers didn’t show up until years after the spill. Additionally, evidence suggests DNA damage occurred to these workers that could lead to cancers and alterations in hormone status.

The responsibility for both the immediate and long-term responses can only be led by the administration from the highest levels. This is not an appropriate role for corporations, which cannot be trusted to put the long-term interests and needs of the affected communities ahead of their business concerns. The BP oil spill is a clear example of why we cannot allow the very corporation that caused the problem in the first place to be trusted with monitoring its potential health effects. The protection of public health has always been a key responsibility of the federal government, and we have previously called for the federal government to takeover this responsibility with respect to the gulf oil spill.

This is not the first time the nation has faced such a crisis, and it won’t be the last. We have faced public health threats from the World Trade Center attack on 9/11, Hurricane Katrina, and the Exxon Valdez oil spill, and from infectious agents such as SARS, Avian flu, and H1N1 flu that fortunately did not reach crisis proportions but could have. The responses, while effective, have not been always been well coordinated. The Government Accountability Office in 2008 identified important lessons from the WTC response that could help develop responder health programs in the event of a future disaster, but the GAO recommendations have not been fully addressed.

The gulf oil crisis reminds us that it is essential to have a response plan that is activated early and can continue into the future for as long as needed. We need to establish an architecture complete with clear lines of responsibilities and acknowledged trigger points for action. It should facilitate the involvement of the appropriate federal health agencies in addressing a potential public health emergency— from watchful waiting to emergency response to long-term monitoring and management.

We do not need a new entity to put this system in place. Government has the expertise among the many HHS agencies to handle any given public health emergency, but different players may be called on at different times depending on the event. This transfer of responsibilities will occur mostly between HHS agencies, but it may also involve nonhealth agencies as well. Obviously this is now the case with the gulf oil crisis, but it could occur with other incidents as well. With a large-scale infectious agent attack, for example, medication may need to be delivered to the homes of many affected Americans, and it has been suggested that the U.S. Postal Service could fill this role since they know how to get parcels to nearly every U.S. home.

We propose that a single, high-ranking HHS official be designated to launch and oversee the coordinated response plan implemented whenever a situation arises that can threaten public health. We recommend this leadership role go to the assistant secretary for health, or ASH. The ASH should have responsibility for determining when and how the response to a public health threat moves into the initial emergency phase and when it transitions to a long-term monitoring and management phase. The ASH would have responsibility for ensuring—in conjunction with other federal, state, and local agencies, academics, and the private sector—that needed services are delivered and information is collected, and that data, information, and resources are transferred to the responsible HHS agency or agencies.

This approach does not require new agencies or significant new authorities. But it will require the following:

• Clarification of roles and responsibilities of all agencies and offices involved
• Robust surveillance systems with standardized data that can analyze information collected from a variety of sources
• Sufficient financial resources and the appropriate workforce to develop capacity and maintain long-term monitoring systems
• Mechanisms in place to address ongoing medical needs for individuals affected by the crisis
• A financial infrastructure to assure funding is available for immediate and longer-term health needs

This paper looks at the issues that must be addressed in the immediate (emergency) response situation to facilitate the eventual handover to a long-term monitoring and management system, what that system should incorporate, how to trigger the emergency response and the long-term monitoring phase, and how the different agencies should work together in a seamless fashion. But first, it examines how our current system lacks an overall plan to maximize the contribution of all available agencies and organize the strongest possible public health response.

Read the full report (pdf)

Download the executive summary (pdf)

Video: The BP Oil Disaster and Public Health

This article was originally posted on Climate Progress

This makes me think that perhaps a new simple mental picture of the situation is needed. We can look at climate models, and they tell us what we can expect, but it is also useful to have an idea of why increased greenhouse gas concentrations result in higher surface temperatures. The saying “Everything should be made as simple as possible, but not simpler” has been attributed to Albert Einstein, which also makes me wonder if we – the scientists – need to reiterate the story of climate change in a different way.

Gavin has already discussed this (also see here and here), but it may be necessary to tell story over again, with a slightly different slant. So how can we explain how the greenhouse effect (GHE) work in both simple terms and with a new angle? I also want to explain why the middle atmosphere cools with increasing greenhouse gas concentrations associated with an increased GHE. Here I will try to present a conceptual and comprehensive picture of GHE, explaining both the warming in the lower part of the atmosphere as well as the cooling aloft, and where only the most central features are included. Also, it is important to provide a good background, and we need to start with some very fundamental facts.

Four main physical aspects
Several factors are involved, and hence it may be useful to write a simple recipe for the GHE. This recipe then involves four main ingredients: (i) the relationship between temperature and light, (ii) the planetary energy balance, (iii) the distance light travels before being absorbed, and (iv) the relationship between temperature and altitude.

(i) Temperature and light
Energy can be transmitted in many different ways, involving photons (light or electromangetic radiation), conduction, and motion. Most of these require a medium, such as a gas, fluid, or a solid, but space is basically a void through which photons represent virtually the only form for energy transfer. Hence, planets tend to gain or lose energy to space in the form of photons, and we often refer to the energy loss as ‘radiative heat loss’.

A fundamental law of physics, known as the Planck’s law, says that radiative heat loss from any object depends on its temperature. Planck’s law also explains the colour of the light, or its wavelength, and hence explains why iron gets red hot when heated sufficiently.

Figure 1. Illustration of Planck’s law, where the different curves represent objects with different temperature. The y-axis is marks the intensity and the x-axis the wave length (colour) of the light emitted by bodies with a given temperature (PDF-version and R-script generating the figure.)

Planck’s law predicts that the light from an object with a temperature of 6000K – such as the solar surface – produces light that is visible, whereas objects with a temperature of 288K produce light with a wavelength that our eyes are not able to see (infra red). This is illustrated in Figure 1 showing how the light intensity (y-axis; also referred to as ‘flux density‘) and the colour of the light (wave length) vary for objects with different temperatures (here represented by different curves). The yellow curve in the figure represents the solar surface and the light blue curve the earth.

(ii) The planetary energy balance
The planetary energy balance says that our planet loses heat at the same rate as it receives energy from the sun (otherwise it would heat or cool over time). This is because energy cannot just be created or destroyed (unless it involves nuclear reactions or takes place on quantum physics scales).

The planets’ distance from the sun and the brightness of its surface dictates how much energy it receives from the sun, as the light gets dimmer when it spreads out in space, as described by Gauss’ theorem.

Figure 2. A schematic of the solar system, where the energy received by the earth is the sunlight intercepted by its cross-section, and where the heat loss on average is due to thermal emission from the whole surface area of the planet. As the sunlight travels away from the sun, it spreads out over larger space and gets dimmer.

The energy flowing from the sun is intercepted by the earth with energy density described by the ‘solar constant‘ (S₀=1366W/m²), and the amount of energy intercepted is the product between this flux density and the earth’s disc (minus the reflected light due to the planet’s albedo: A ~0.3). The average heat loss is given by the product of earth’s surface and its black body radiation:

S₀/4 (1-A) = σT⁴,

where σ=5.67 x 10^-8W/(m² K⁴) is the Stefan-Boltzman constant. This gives a value of 255K, known as the emission temperature.

Figure 3 shows a comparison between observed surface temperature and calculated emission temperature for the planets in the solar system, based on the balance between energy from the sun and heat loss due to black body emission. In these simple calculations, the greenhouse effect is neglected, and the black body radiation can be derived from Planck’s law. The calculations agree quite well with the observations for most of the objects in our solar system, except for Venus which is known to harbour a strong GHE and has a hotter surface than Mercury despite being about twice as far away from the sun.

Figure 3. Comparison between calculated emission temperature and the observed surface temperatures for planets and moons in our solar system. The calculations estimate the reduction in the energy flux density with distance away from the sun (Gauss’ theorem) and the black body radiation describing the rate of planetary heat loss. Here, the greenhouse effect has been neglected in the calculations, but the GHE does affect the observed surface temperatures. Venus is a bright planet (high albedo) with a thick atmosphere mostly made up of CO₂, which explains higher surface temperature than inferred from a pure energy balance (PDF-version and R-script generating the figure).

(iii) Light absorption
It is also clear that our planet is largely heated at the surface because the light from the sun – which is visible for our eyes – penetrates the atmosphere without much absorption (hence we can see the sun from the ground). However, the atmosphere is a medium of gas and particles that can absorb and scatter light, depending on their wavelength (hence explain why the sky is blue and sunsets orange).

The distance light travels before being absorbed – optical depth – can vary with the light’s wavelength and the medium through which is travels. The optical depth in our atmosphere is different for visible and infra-red light.

Infra-red light is absorbed by molecules, which in turn get more energetic, and the excited molecules will eventually re-emit more infra-red light in any random direction or transfer excess energy to other molecules through collisions. In a optically thick (opaque) atmosphere, there will be a cascade of absorption and re-emission.

Hence, whereas the planet is heated at the surface, it’s main heat loss takes place from a height about 5.5 km above the ground, where most of the radiation is free to escape out to space. The optical depth dictates how deep into the planet’s atmosphere the origin is for most of the planet’s infra-red light (the main planetary heat loss) that can be seen from space. Furthermore, it is the temperature at this level that dictates the magnitude of the heat loss (Planck’s law), and the vertical temperature change (lapse rate) is of course necessary for a GHE. The temperature at this level is the emission temperature, not to be confused by the surface temperature.

We know that the optical depth is affected by CO₂ – in fact, this fact is the basis for measuring CO₂ concentrations with infra-red gas analysers. Molecules composed of three or more atoms tend to act as greenhouse gases because they can possess energy in terms of rotation and vibrations which can be associated with the energy of photons at the infra-red range. This can be explained by theory and be demonstrated in lab experiments. Other effects are present too, such as pressure and Doppler broadening, however, these are secondary effects in this story.

(iv) The relationship between temperature and altitude
There is a well-known relationship between temperature and height in the troposphere, known as the ‘lapse rate‘ (the temperature decreases with height at a rate -6K/km). The relationship between temperature and altitude can also be seen in the standard atmosphere. The lapse rate can be derived from theory for any atmosphere that is the hydrostatically stable condition with maximum vertical temperature gradient, but it is also well-known within meteorology. Thus, given the height and value of the emission temperature, we can get a simple estimate for the surface temperature: 255K + 5.5km * 6K/km = 288K (=15^oC; close to the global mean estimated from observations given by NCDC of ~14^oC).

Enhanced greenhouse effect
The term known as the ‘enhanced greenhouse effect’ describes a situation where the atmosphere’s becomes less transparent to infra-red light (reduced optical depth), and that the heat loss must take place at higher levels. Moreover, an observer in space cannot see the infra-red light from as deep levels as before because the atmosphere has become more opaque.

Figure 4. A simple schematic showing how the planet is heated at the surface, how the temperature (blue) decreases with height according to the lapse rate, and how infra-red light (wiggly arrows) is absorbed and re-emitted at various stages on its way up through the atmosphere. Energy is also transferred through vertical motion (convection), evaporation, and condensation too (latent heat), but that doesn’t affect this picture, as they all act to restore the vertical structure toward the hydrostatically stable lapse rate in the long run. At the top of the atmosphere, the infra-red light escapes freely out to space, and this is where the planet’s main heat loss takes place. This level is determined by the optical depth, and the heat loss depends on the temperature here. (click on figure for animation)

The effect of heightened level of heat loss on the surface temperature is illustrated in Figure 4, where the emission temperature and lapse rate are given if we assume an energy balance and a hydrostatically stable atmosphere on average (a generally hydrostatically unstable atmosphere would be bad news).

Hence, a reduced optical depth explains why atmospheres are not easily ‘saturated‘ and why planets such as Venus have surface temperatures that are substantially higher than the emission temperature. Planets with a thin atmosphere and insignificant greenhouse effect, on the other hand, have a surface temperature that is close the the estimates from the planetary energy balance model (Figure 3).

Feedback processes
The way the atmosphere reacts to changes in the optical depth is more complicated, due to a number of different feedback mechanisms taking place. But to get a simple overview, it is useful to keep in mind that the optical depth is sensitive to how much water vapour (humidity) there is in the air, and that the lapse rate is sensitive to the composition of the atmosphere (i.e. humidity). Furthermore, the albedo A is affected by clouds, snow, ice, and vegetation, all of which affect the way the earth receives energy from the sun.

In our simple picture, feedback processes affect changes in the height of the level where most heat loss takes place, the slope of the lapse rate, and heating at the surface (and hence the emission temperature).

So why is the upper atmosphere cooled then?
The upper atmosphere, comprising the stratosphere and mesosphere, is expected to cool during an AGW, as shown by the GCMs. So what is happening there? This is when the picture becomes more complicated.

Since CO₂ mostly absorbs/re-emits infra-red light at around 14 microns, an increaed concentration in the troposphere will reduce the upward infra-red radiation at this band. The total energy is roughly constant, but it is made up from increased emissions at other bands because it’s warmer. There is less absorption by CO₂ of upwelling infra-red light above the troposphere, but increased emission as a function of increased concentrations. Thus there is a cooling.

Controversy?
Can this picture be falsified, e.g. if other factors were to play a role too? For instance, can this situation be altered by changes in the sun?

Changes in the sun can of course affect the amount of energy received by the earth through changes in its output, variations in the intensity of UV-light, or perhaps even clouds through galactic cosmic rays. But it’s hard to see any systematic long-term trend in the level of solar activity over the last 50 years, and it is difficult to see how solar activity may have an effect while other factors, such as GHGs, don’t. Gavin and I recently published a study on the response to both solar activity and GHGs, and found similar magnitude for both forcings in both observations and the GISS GCM.

There have been claims of negative feedbacks, such as the “iris effect“. One would expect negative feedbacks in general to dampen the response to most forcings, unless they involve a particular process that is active for a particular forcing. In other word, why would a negative feedback act for GHGs but not for solar forcing? Many feedbacks, such as changes in atmospheric moisture, cloudiness, and atmospheric circulation should be similar for most forcings.

Another question is why we do see a global warming trend if the negative feedbacks were most important (Figure 5). Negative feedbacks usually imply quiet conditions in a complex system, whereas positive feedbacks tend to lead to instabilities, often manifested as internal and spontaneous oscillations (see Figure 5). It is reasonable to expect the feedback processes to affect natural variations as well as forced changes such as an enhanced GHE, orbital changes, volcanoes, or changes in the sun.

Figure 5. Estimates of the global and annual mean temperature based on a number of different data sets, including both traditional analyses as well as re-analyses (also see the last 15 years).

The point about negative feedback also brings up another interesting issue: Negative feedbacks usually act to restore a system to a particular zero-level state. What would the zero-state be for our climate? No greenhouse effect or some preferred level of greenhouse warming? There is already a natural GHE that, together with other atmospheric effects, can account for about 32^oC higher global mean surface temperature. What makes this state so special, and can we explain the present natural GHE in the presence of negative feedbacks (consider starting from a state with no GHE)?

Hence, claims of negative feedback is controversial because all these tough questions then need to be addressed. We can write down a simple recipe for the GHE, but it is indeed challenging to reconcile a presence of a negative feedback with our observations, or explain the current observed global warming in any other terms.

This article was originally posted on Real Climate

… and why does it matter?

There is a lot of discussion this week about a new paper in PNAS (Anderegg et al, 2010) that tries to assess the credibility of scientists who have made public declarations about policy directions. This come from a long tradition of papers (and drafts) where people have tried to assess the state of the ’scientific consensus’ (Oreskes, Brown et al, Bray and von Storch, Doran and Zimmerman etc.). What has bedevilled all these attempts is that since it is very difficult to get scientists to respond to direct questions (response rates for surveys are pitiful), proxy data of some sort or another are often used that may or may not be useful for the specifics of the ‘consensus’ being tested (which itself is often not clearly defined). Is the test based on agreeing with every word in the IPCC report? Or just the basic science elements? Does it mean adhering to a specific policy option? Or merely stating that ’something’ should be done about emissions? Related issues arise from mis-specified or ambiguous survey questions, and from the obvious fact that opinions about climate in general are quite varied and sometimes can’t easily be placed in neatly labelled boxes.

Given these methodological issues (and there are others), why do people bother?

The answer lies squarely in the nature of the public ‘debate’ on climate. For decades, one of the main tools in the arsenal of those seeking to prevent actions to reduce emissions has been to declare the that the science is too uncertain to justify anything. To that end, folks like Fred Singer, Art Robinson, the Cato Institute and the ‘Friends’ of Science have periodically organised letters and petitions to indicate (or imply) that ‘very important scientists’ disagree with Kyoto, or the Earth Summit or Copenhagen or the IPCC etc. These are clearly attempts at ‘arguments from authority’, and like most such attempts, are fallacious and, indeed, misleading.

They are misleading because as anyone with any familiarity with the field knows, the basic consensus is almost universally accepted. That is, the planet is warming, that human activities are contributing to the greenhouse gases in the atmosphere (chiefly, but not exclusively CO₂), that these changes are playing a big role in the current warming, and thus, further increases in the levels of GHGs in the atmosphere are very likely to cause further warming which could have serious impacts. You can go to any standard meeting or workshop, browse the abstracts, look at any assessment, ask any of the National Academies etc. and receive the same answer. There are certainly disputes about more detailed or specific issues (as there is in any scientific field), and lots of research continues to improve our quantitative understanding of the system, but the basic issues (as outlined above) are very widely (though not universally) accepted.

It is in response to these attempts to portray the scientific community as fractured and in disagreement, that many people have tried to find quantitative ways to assess the degree of consensus among scientists on the science and, as with this new paper, the degree of credibility and expertise among the signers of various letters advocating policies.

It is completely legitimate to examine the credentials of people making public statements (on any side of any issue) – especially if they make a claim to scientific expertise. It does make a difference if medical advice is being given by a quack or the Surgeon General. The database that Jim Prall has assembled allows anyone to look this expertise up – and since any new source of information is useful, we think this can be generally supported. Prall’s database has a number of issues of course, most of them minor but some which might be considered more problematic: it relies on citation statistics, which have well-known problems (though mostly across fields rather than within them), it uses Google Scholar rather than the standard (ISI) citation index, and there are almost certainly some confusions between people with similar names. Different methodologies could be tried – ranking via h-index perhaps – but the as long as small differences are not blown out of proportion, the rankings he comes up with appear reasonable.

So it is now possible to estimate an expertise level associated with any of the various lists and letters that are out there. Note that it is worth distinguishing between letters that have been voluntarily signed and lists that have been gathered with nothing but political point scoring in mind (the Inhofe/Morano list was egregious in its cherry picking of quotes in order to build up its numbers and can’t be relied on as an accurate reflection of peoples opinions in any way, and similarly contributing to RealClimate is not a statement about policy preferences!). Additionally, it isn’t always clear that every signatory of each letter really believes every point in the statement. For instance, does Lindzen really believe that attribution is impossible unless current changes exceed all known natural variations (implying that nothing could be said unless we got colder than Snowball Earth or warmer than the Cretaceous or sea level rose more than 120 meters….)? We doubt it. But as tests of political preferences, these letters are probably valid indicators.

So, do the climate scientists who have publicly declared that they are ‘convinced of the evidence’ that emission policies are required have more credentials and expertise than the signers of statements declaring the opposite? Yes. That doesn’t demonstrate who’s policy prescription is correct of course, and it remains a viable (if somewhat uncommon) position to acknowledge that despite most climate scientists agreeing that there is a problem, one still might not want to do anything about emissions. Does making a list of signers of public statements, or authors of the IPCC reports, constitute a ‘delegitimization’ of their views? Not in the slightest. If someone’s views are widely discounted, it is most likely because of what they have said, not who they sign letters with.

However, any attempt to use political opinions (as opposed to scientific merit) to affect funding, influence academic hiring, launch investigations, or personally harass scientists has no place in a free society – from whichever direction that comes. In this context, we note that once the categorization goes beyond a self-declared policy position, one is on very thin ice because the danger of ‘guilt by association’. For instance, one of us (Eric) feels more strongly that some of Prall’s classifications in his dataset cross a line (for more on Eric’s view, see his comments at Dotearth).

But will this paper add much to the ‘there [is/is not] a consensus’ argument? Doubtful. People are just too fond of it.

But there really is.

This article was originally posted on Real Climate