THE GREAT GLOBAL WARMING SWINDLE

On March 8, Channel 4 screened The Great Global Warming Swindle, a documentary that branded as a lie the scientific consensus that man-made greenhouse gasses are primarily responsible for climate change.
The film was advertised extensively on Channel 4 and repeatedly previewed and reviewed in newspapers. Writing in the Sunday Telegraph, Christopher Booker declared:

“Only very rarely can a TV documentary be seen as a pivotal moment in a major political debate, but such was Channel 4's The Great Global Warming Swindle last Thursday. Never before has there been such a devastatingly authoritative account of how the hysteria over global warming has parted company with reality.” (Booker, ‘A turning point in climate change,’ Sunday Telegraph, March 11, 2007)
Peter Hitchens commented in the Daily Mail:
“If you were worried about those snaps of polar bears clinging to melting ice-floes, sentenced to a slow death by global warming, you may now relax. They'll be fine. Channel 4 has paid in full for its recent misdemeanours by screening, last Thursday, the brilliant, devastating film The Great Global Warming Swindle.” (Hitchens, ‘Drugs?’, Daily Mail, March 11, 2007)
Doubtless like many who saw the film, the Financial Times’ reviewer was left bewildered:
“Not so long ago, the venerable David Attenborough on the Beeb was telling us that human-driven global warming was real and was coming for us. So that was settled. Now Channel 4, like a dissident schoolboy, is scoffing at the old boy's hobbyhorse and I don't know what to believe.” (’Slaughterhouse three,’ Financial Times, March 10, 2007)
The film opened with scenes of wild weather and environmental disaster accompanied by dramatic captions:
"THE ICE IS MELTING. THE SEA IS RISING. HURRICANES ARE BLOWING. AND IT’S ALL YOUR FAULT.
“SCARED? DON'T BE. IT'S NOT TRUE."
This was immediately followed by a series of equally forthright talking heads:
"We can't say that CO2 will drive climate; it certainly never did in the past."
“We imagine that we live in an age of reason. And the global warming alarm is dressed up as science. But it’s not science; it’s propaganda.”
And:
“We’re just being told lies; that’s what it comes down to.”
The commentary added to the sense of outrage: “You are being told lies.”
This was indeed superficially impressive - when several experts make bold statements on the same theme we naturally assume they must be onto something - but alarm bells should already have been ringing. This, after all, was ostensibly a film about science - about evidence, arguments, research and debate. Why, then, the language of polemic and smear?
The remarkable answer is provided by the film’s writer and director, Martin Durkin:
"I think it [the film] will go down in history as the first chapter in a new era of the relationship between scientists and society. Legitimate scientists - people with qualifications - are the bad guys. It is a big story that is going to cause controversy.
“It's very rare that a film changes history, but I think this is a turning point and in five years the idea that the greenhouse effect is the main reason behind global warming will be seen as total bollocks.” ('“Global Warming Is Lies” Claims Documentary,’ Life Style Extra, March 4, 2007; www.lse.co.uk/ShowStory.asp?story=CZ434669 U&news_headline=global_warming _is_lies_ claims_documentary)
Compare and contrast this with the aim as described in a letter sent by the makers of the film, Wag TV, to Professor Carl Wunsch, a leading expert on ocean circulation and climate who subsequently appeared in the film:
“The aim of the film is to examine critically the notion that recent global warming is primarily caused by industrial emissions of CO2. It explores the scientific evidence which jars with this hypothesis and explores alternative theories such as solar induced climate change. Given the seemingly inconclusive nature of the evidence, it examines the background to the apparent consensus on this issue, and highlights the dangers involved, especially to developing nations, of policies aimed at limiting industrial growth.” (http://ocean.mit.edu/~cwunsch/ papersonline/channel4response)
Wunsch comments:
"I am angry because they completely misrepresented me. My views were distorted by the context in which they placed them. I was misled as to what it was going to be about. I was told about six months ago that this was to be a programme about how complicated it is to understand what is going on. If they had told me even the title of the programme, I would have absolutely refused to be on it. I am the one who has been swindled." (Geoffrey Lean, ‘Climate change: An inconvenient truth... for C4,’ The Independent, March 11, 2007; http://news.independent.co.uk/environment/ climate_change/article2347526.ece)
We will hear more from Wunsch in what follows.


Deeply Deceptive

The film presented viewers with an apparently devastating refutation of the "theory of global warming". And these were not picky, esoteric criticisms. Durkin insisted that the world’s climate scientists are guilty of the most fundamental error imaginable: increased atmospheric carbon dioxide (CO2) is not the cause of higher temperature, as the experts claim. Quite the reverse: increasing atmospheric CO2 is itself the result of rising temperature.
As evidence for this contention, Durkin argued that global surface temperature dropped dramatically between 1945-1975, at a time when CO2 emissions were rapidly rising as a result of the postwar economic boom. According to Durkin, if CO2 emissions were responsible for increasing temperature, then temperature should not have fallen between 1945-1975. Clearly, then, some factor other than CO2 emissions must have caused the subsequent global temperature rise.
But Real Climate, an internet site run by climate scientists, such as NASA’s Dr Gavin Schmidt and Dr William Connelley of the British Antarctic Survey, describes Durkin’s discussion of the 1945-75 period as “deeply deceptive”. (Real Climate, March 9, 2007; www.realclimate.org/index.php/ archives/2007/03/swindled)

In this section of the film, Durkin focused heavily on a graph depicting temperature changes. The graph, Real Climate comments, “looks rather odd and may have been carefully selected”. It appears to show a dramatic cooling between the 1940s and 1970s. But try flipping between the film’s version of the global temperature record (shown above left) and the temperature plot that normally appears in the scientific literature (shown above right) The supposed cooling looks rather less evident in this second graph.
Without knowing more details of how Durkin may have manipulated the data plotted in his graph, it is difficult to comment on the presentation. What we can say is that Durkin’s "four decades of cooling", implying a relentless temperature drop over 40 years, is not an accurate description of the trend over this period. There was some cooling for +part+ of this time but also some plateauing, with fluctuations up and down.
But why did the temperature not simply rise in line with the post-war increase in greenhouse gas emissions?
In fact, as is well-known, the absence of a global rise in temperature between 1945-75 is explained by the release of large amounts of industrial pollutants, called sulphate aerosols, into the atmosphere. These particles have a braking effect on global warming, known as “global dimming”. By shielding some of the incoming solar energy, sulphate aerosols mask the underlying warming effect generated by rising levels of CO2. By the 1980s, however, stronger warming had exceeded this masking effect and global temperature has since continued to rise. As Real Climate notes, by failing to explain the science behind this phenomenon the programme makers were guilty of “lying to us by omission.”


The Ice Cores

The film repeatedly gave the impression that mainstream science argues that CO2 is the sole driver of rising temperatures in the Earth's climate system. But this is not the case. Climate scientists are well aware that solar activity plays a role, though a minor one at present, as do long-term periodic changes in the Earth's orbit, known as Milankovitch cycles. (See: http://en.wikipedia.org/ wiki/Milankovitch_cycles)
The point is that there is a vast body of evidence that very strongly supports the hypothesis that greenhouse gas emissions, of which CO2 is the most important, are primarily responsible for recent global warming. The 4th and most recent scientific assessment of the Intergovernmental Panel on Climate Change (IPCC) concludes:
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely [.i.e. probability greater than 90%] due to the observed increase in anthropogenic greenhouse gas concentrations." ('Climate Change 2007: The Physical Science Basis,' Summary for Policymakers, IPCC, February 2007, page 10; www.ipcc.ch/SPM2feb07.pdf)
We then come to one of the film's most misleading arguments. Antarctic ice cores show that rises in levels of CO2 have lagged 800 years behind temperature rises at specific times in the geological past. This, argued Durkin, +proves+ that CO2 cannot be responsible for global warming - instead global warming is responsible for increasing levels of CO2. But this was a huge howler.
What Durkin's film failed to explain was that the 800-year lag happened at the end of ice ages which occur about every 100,000 years. (See: www.realclimate.org/index.php/ archives/2004/12/co2-in-ice-cores)
Scientists believe that the end of an ice age is likely triggered when the amount of heat reaching the Earth rises as a result of a periodic change in the Earth's orbit around the sun. Jeff Severinghaus, Professor of Geosciences at Scripps Institution of Oceanography, explains why the rise in CO2 initially lags behind the temperature rise:
"The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend." (Real Climate, 'What does the lag of CO2 behind temperature in ice cores tell us about global warming?’, December 3, 2005; www.realclimate.org/index.php /archives/2004/12/co2-in-ice-cores/)
The best current explanation for the lag of 800 years is that this is how long it takes for CO2, absorbed by the ocean in an earlier warm period, to be "flushed out" at the end of an ice age. Once that CO2 has been released into the atmosphere its heat-trapping properties as a greenhouse gas lead to even stronger warming: an example of positive feedback. (See Caillon et al., 'Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination III,' Science, 14 March 2003: Vol. 299. no. 5613, pp. 1728 - 1731)
Professor Severinghaus summarises:
"In other words, CO2 does not initiate the warmings, but acts as an amplifier once they are underway."
Durkin’s analysis, then, was way off the mark.
The film’s claim that solar activity might account for recent warming is also without credibility. In September 2006, the Times reported the latest findings from researchers writing in the top journal, Nature:
“Scientists have examined various proxies of solar energy output over the past 1,000 years and have found no evidence that they are correlated with today's rising temperatures. Satellite observations over the past 30 years have also turned up nothing. ‘The solar contribution to warming... is negligible,’ the researchers wrote in the journal Nature.” (Anjana Ahuja, ‘It's hot, but don't blame the Sun,’ The Times, September 25, 2006)
The film's other scientific claims can be similarly dismissed. Carl Wunsch - who, as discussed, appeared in the film - comments:
“What we now have is an out-and-out propaganda piece, in which there is not even a gesture toward balance or explanation of why many of the extended inferences drawn in the film are not widely accepted by the scientific community. There are so many examples, it's hard to know where to begin, so I will cite only one: a speaker asserts, as is true, that carbon dioxide is only a small fraction of the atmospheric mass. The viewer is left to infer that means it couldn't really matter. But even a beginning meteorology student could tell you that the relative masses of gases are irrelevant to their effects on radiative balance. A director not intending to produce pure propaganda would have tried to eliminate that piece of disinformation.” (http://ocean.mit.edu/~cwunsch/ papersonline/channel4response)
For further help in understanding the weakness of the film’s claims, see the following resources:
Real Climate, 'Swindled',
http://www.realclimate.org/index.php/archives/2007/03/swindled
Campaign Against Climate Change, including a rebuttal to the film by Sir John Houghton, who chairs the Scientific Assessment Working Group of the Intergovernmental Panel on Climate Change: http://portal.campaigncc.org/node/1820
Royal Society: Facts and fictions about climate change:
http://www.royalsoc.ac.uk/page.asp?id=4761


“I Was Duped” - Déjà Vu?

Many readers will be aware that Durkin has previous ‘form’. In 1997, Channel 4 broadcast his three-part series, Against Nature, which suggested present-day environmentalists were the true heirs of the Nazis. (See George Monbiot, ‘The Revolution Has Been Televised,’ The Guardian, December 18, 1997; www.monbiot.com/archives/1997/ 12/18/the-revolution-has-been-televised/)
Several interviewees who appeared in the film felt they had been misled about the programme-maker’s agenda. Responding to complaints, the Independent Television Commission (ITC) found that the editing of interviews with four contributors had "distorted or misrepresented their known views". (Geoffrey Lean, ‘Climate change: An inconvenient truth... for C4,’ The Independent, March 11, 2007; http://news.independent.co.uk/ environment/climate_change/article2347526.ece)
In addition, the ITC found: "The interviewees had also been misled as to the content and purpose of the programmes when they agreed to take part." (Paul McCann, ‘Channel 4 told to apologise to Greens,’ The Independent, April 2, 1998)
Ten years on, it appears that history may have repeated itself. In his letter of complaint to the film-makers cited above, Carl Wunsch writes:
“I have some experience in dealing with TV and print reporters and do understand something of the ways in which one can be misquoted, quoted out of context, or otherwise misinterpreted. Some of that is inevitable in the press of time or space or in discussions of complicated issues. Never before, however, have I had an experience like this one. My appearance in the ‘Global Warming Swindle’ is deeply embarrassing, and my professional reputation has been damaged. I was duped---an uncomfortable position in which to be.
“At a minimum, I ask that the film should never be seen again publicly with my participation included. Channel 4 surely owes an apology to its viewers, and perhaps WAGTV owes something to Channel 4. I will be taking advice as to whether I should proceed to make some more formal protest.” (http://ocean.mit.edu/~cwunsch/ papersonline/channel4response)
Eight of the scientists in the film - John Christy, Paul Reiter, Richard Lindzen, Paul Driessen, Roy Spencer, Patrick Michaels, Fred Singer and Tim Ball - are linked to American neo-conservative and right-wing think-tanks, many of which have received tens of millions of dollars from Exxon.
Greenpeace provides a fascinating online ’map’ detailing how Exxon funds these climate sceptics. Go to: http://www.exxonsecrets.org/ index.php?mapid=831 (click ‘Launch’ then click ‘skip intro’)
In his book, Green Backlash, environmental journalist Andrew Rowell noted that Fred Singer has also attacked scientific and environmental stances on other green issues such as ozone, acid rain, automobile emissions and even whaling. Singer has worked for companies such as Exxon, Shell, Arco, Unocal and Sun.
According to the Environmental Research Foundation, a non-governmental organisation:
“For years, Singer was a professor at the University of Virginia where he was funded by energy companies to pump out glossy pamphlets pooh-poohing climate change.” (Quoted, Sharon Beder, Global Spin, Green Books, 1997, p.94)
Rowell wrote that a quarter of Patrick Michaels’ research funding was reportedly received from companies such as Edison Electric Institute, the largest utility trade association in America. Michaels’ magazine, World Climate Review, was funded by the Western Fuel Association and a video produced by him was funded by coal companies and distributed by the Denver Coal Club. (Rowell, Green Backlash, Routledge, 1996, p.143)
Both Singer and Michaels represented the fossil fuel lobby’s Global Climate Coalition and the Competitive Enterprise Institute, a leader in global warming scepticism.
Journalist Ross Gelbspan noted that in May 1995, Richard Lindzen and Patrick Michaels were hired as expert witnesses to testify on behalf of Western Fuels Association, a $400 million consortium of coal suppliers and coal-fired utilities. Gelbspan said of Lindzen:
“I don't know very many supporters of Mr Lindzen who are not in the pay of the fossil fuel lobby. Dr Lindzen himself, his research is publicly funded, but Dr Lindzen makes, as he told me, $2,500 a day consulting with fossil fuel interests, and that includes his consulting with OPEC, his consulting with the Australian coal industry, his consulting with the US coal industry and so forth. That's not to say Dr Lindzen doesn't believe what he says, but it is to say that he stands in very sharp distinction to really just about virtually all of the climate scientists around the world.” (Tony Jones, ‘Journalist puts global warming sceptics under the spotlight,’ Australian Broadcasting Corporation, March 7, 2005; www.abc.net.au/lateline/ content/2005/s1318067.htm)
Journalist George Monbiot wrote of Philip Stott:
“Professor Stott is a retired biogeographer. Like almost all the prominent sceptics he has never published a peer-reviewed paper on climate change. But he has made himself available to dismiss climatologists' peer-reviewed work as the ‘lies’ of ecofundamentalists.” (Monbiot, ‘Beware the fossil fools,’ The Guardian, April 27, 2004; http://environment.guardian.co.uk/ climatechange/story/0,,1829315,00.html)
Paul Driessen is a fellow at two right-wing think tanks in the US, which are part of the Wise Use movement. One of the think tanks is headed by Ron Arnold, who has spent the last twenty years attacking the environmental movement. His fellow director is a fundraiser for America's gun lobby. The list goes on...
By contrast, Greenpeace spokeswoman Mhairi Dunlop said her organisation had been interviewed by Durkin but none of the material had been included in the film:
"They interviewed us but I guess what we said didn't fit in with the [story] they were peddling." (McCandless, op. cit)
Following the film’s broadcast, Professor Martin Rees, president of the Royal Society - the government-sponsored academy of sciences for the United Kingdom - has said that many factors contribute to global warming but it is clear that emissions of "greenhouse gases," particularly CO2, are to blame for most of the current temperature rise. Rees added:
"Those who promote fringe scientific views but ignore the weight of evidence are playing a dangerous game. They run the risk of diverting attention from what we can do to ensure the world's population has the best possible future." (Ibid)
On March 11 the Observer published a letter from a group of climate scientists responding to Durkin’s film:
“This programme misrepresented the state of scientific knowledge on global warming, claiming climate scientists are presenting lies. This is an outrageous statement...
“We defend the right of people to be sceptical, but for C4 to imply that the thousands of scientists and published peer-reviewed papers, summarised in the recent international science assessment, are misguided or lying lacks scientific credibility and simply beggars belief.” (Alan Thorpe, Natural Environment Research Council, Brian Hoskins, University of Reading, Jo Haigh, Imperial College London, Myles Allen, University of Oxford, Peter Cox, University of Exeter, Colin Prentice, QUEST Programme, letter to the Observer, Sunday March 11, 2007;
http://observer.guardian.co.uk/ letters/story/0,,2031117,00.html)
Viewed from one perspective, Channel 4 has done a huge public disservice in spreading absurd and mendacious arguments guaranteed to generate confusion. This at a time when a fragile momentum is building on the need to take urgent action on the very real threat of catastrophic climate change.
But from another perspective it may well be that this film does for climate scepticism what Tony Blair’s “dodgy dossiers” did for the pro-war movement ahead of the invasion of Iraq. Wildly distorted propaganda often does have a powerful initial impact. But stretched beyond a certain point of unreality, it also has a tendency to turn on, and bite, the propagandists.
Durkin’s grandiose prediction that his film “will go down in history” will surely prove correct, although perhaps not for the reasons he imagined.


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feature picture

Global Warming Causes

Photo: Smokestacks

What Causes Global Warming?
Scientists have spent decades figuring out what is causing global warming. They've looked at the natural cycles and events that are known to influence climate. But the amount and pattern of warming that's been measured can't be explained by these factors alone. The only way to explain the pattern is to include the effect of greenhouse gases (GHGs) emitted by humans.

To bring all this information together, the United Nations formed a group of scientists called the Intergovernmental Panel on Climate Change, or IPCC. The IPCC meets every few years to review the latest scientific findings and write a report summarizing all that is known about global warming. Each report represents a consensus, or agreement, among hundreds of leading scientists.
One of the first things scientists learned is that there are several greenhouse gases responsible for warming, and humans emit them in a variety of ways. Most come from the combustion of fossil fuels in cars, factories and electricity production. The gas responsible for the most warming is carbon dioxide, also called CO2. Other contributors include methane released from landfills and agriculture (especially from the digestive systems of grazing animals), nitrous oxide from fertilizers, gases used for refrigeration and industrial processes, and the loss of forests that would otherwise store CO2.
Different greenhouse gases have very different heat-trapping abilities. Some of them can even trap more heat than CO2. A molecule of methane produces more than 20 times the warming of a molecule of CO2. Nitrous oxide is 300 times more powerful than CO2. Other gases, such as chlorofluorocarbons (which have been banned in much of the world because they also degrade the ozone layer), have heat-trapping potential thousands of times greater than CO2. But because their concentrations are much lower than CO2, none of these gases adds as much warmth to the atmosphere as CO2 does.
In order to understand the effects of all the gases together, scientists tend to talk about all greenhouse gases in terms of the equivalent amount of CO2. Since 1990, yearly emissions have gone up by about 6 billion metric tons of "carbon dioxide equivalent" worldwide, more than a 20 percent increase.

Global warming effect seen in pole


Icebergmelt
Scientists who have just completed several years of pole-to-pole flights have uncovered data that confirms some of the deep worries about human-generated global warming that had been predicted by computer-based mathematical models.
The flights offered the most comprehensive look to date at greenhouse gases accumulating in the atmosphere, warming the planet and setting off chains of effects on climate.
The data mined by the National Center for Atmospheric Research team will take years to analyze.  Asked about his first overall impression, however, the project's chief investigator, Steven Wofsy, a professor of Atmospheric and Environmental Science at Harvard University, said, "It certainly doesn’t make me feel more relaxed" about human-induced climate change.
Unlike satellite or ground-based data, the information gleaned on flights that dipped from as high as 40,000 feet to below 500 feet recorded and demonstrated some of the mechanisms that put additional greenhouse gases into the atmosphere, adding a level of precision that mathematical models and satellite observation often lack.
"It's like looking at an X-ray from the '60s versus a CAT scan today," Wofsy said of the difference in the data.
Scientists were surprised to find strong evidence that ocean surfaces laid bare by melting ice are emitting methane at a "significant" rate likely to have "global impact," Wofsy said.
"It confirms a concern that’s been raised about the removal of ice from the arctic." Wofsy said. "It does look to be significant, and that’s a new result there."
The process by which the open ocean surface is emitting methane, a more potent greenhouse gas than carbon dioxide, is uncertain, Wofsy said, adding that it likely is not from frozen masses of methane known to be in deep oceans, nor from methane being exhaled from newly thawed tundra.
The discovery of this net addition to the atmosphere confirms a "feedback" mechanism by which one phenomenon has a multiplier effect on the contents of Earth's atmosphere, where greenhouse gases have been accumulating at a rapid rate in modern industrial crimes.
Here, not only does the white ice stop reflecting the sun's energy into the atmosphere (the albedo effect), but its absence also adds more blanketing gases that trap reflected heat.
"It had not been forecast that we would see evidence of methane coming from the deep ocean regions," Wofsy said. "Maybe we should’ve known, but that was a surprise."
In the tropics, the flight teams were able to see and measure how nitrogen oxide and nitrogen dioxide accumulate in the upper atmosphere. In addition, the flights more closely observed the interchange of oxygen and carbon dioxide in the ocean, a product of photosynthesis by algae and die-offs of that algae, among other processes.
The flights not only allowed researchers to chronicle the distribution of CO2 but count the molecules and use the data to test mathematical models' predictions.
The research was conducted jointly by the atmospheric center and the National Science Foundation, which along with the National Oceanic and Atmospheric Administration, provided funding.
Known by its acronym, HIPPO, the effort used an advanced aircraft that would dip down to 500 feet or lower at every two degrees of latitude, collecting data throughout the air column in an effort to determine where and when planet-warming particles enter the atmosphere.
At a time when partisan politicians and climate skeptics have whittled away at uncertainties in models and studies, the data have the potential to be a trove of factual rebuttal. Two peer-reviewed papers already have been produced from the data, and more are expected.

Global warming

Global warming is the rise in the average temperature of Earth's atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earth's mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.[2] Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases produced by human activities such as the burning of fossil fuels and deforestation.[3][4][5][6] These findings are recognized by the national science academies of all major industrialized nations.[7][A]Climate model projections were summarized in the 2007 Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC). They indicated that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest.[8] The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.[9][10]
(According to AR4) warming and related changes will vary from region to region around the globe.[11] The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well a probable expansion of subtropical deserts.[12] Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include a more frequent occurrence of extreme-weather events including heat waves, droughts and heavy rainfall, ocean acidification and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields[13] and the loss of habitat from inundation.

Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC),[14] whose ultimate objective is to prevent dangerous anthropogenic (i.e., human-induced) climate change.[15] Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions[16]:10[17][18][19]:9 and to assist in adaptation to global warming.[16]:13[19]:10[20][21] Parties to the UNFCCC have agreed that deep cuts in emissions are required,[22] and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level.[22][B] A 2011 report of analyses by the United Nations Environment Programme[23] and the International Energy Agency[24] suggests that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC's 2 °C target.

refer to caption
Global mean land-ocean temperature change from 1880–2011, relative to the 1951–1980 mean. The black line is the annual mean and the red line is the 5-year running mean. The green bars show uncertainty estimates. Source: NASA GISS.
Map of temperature changes across the world
key to above map of temperature changes
The map shows the 10-year average (2000–2009) global mean temperature anomaly relative to the 1951–1980 mean. The largest temperature increases are in the Arctic and the Antarctic Peninsula. Source: NASA Earth Observatory
refer to caption
Fossil fuel related CO2 emissions compared to five of IPCC's emissions scenarios. The dips are related to global recessions. Image source: Skeptical Science.

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Pacific Islands On Equator May Become Refuge for Corals in a Warming Climate Due to Changes in Ocean Currents

Pacific Islands On Equator May Become Refuge for Corals in a Warming Climate Due to Changes in Ocean Currents

Scientists have predicted that ocean temperatures will rise in the equatorial Pacific by the end of the century, wreaking havoc on coral reef ecosystems. But a new study shows that climate change could cause ocean currents to operate in a surprising way and mitigate the warming near a handful of islands right on the equator. As a result these Pacific islands may become isolated refuges for corals and fish.
Here's how it would happen, according to the study by Woods Hole Oceanographic Institution scientists Kristopher Karnauskas and Anne Cohen, published April 29 in the journal Nature Climate Change.
At the equator, trade winds push a surface current from east to west. About 100 to 200 meters below, a swift countercurrent develops, flowing in the opposite direction. This, the Equatorial Undercurrent (EUC), is cooler and rich in nutrients. When it hits an island, like a rock in a river, water is deflected upward on the island's western flank and around the islands. This well-known upwelling process brings cooler water and nutrients to the sunlit surface, creating localized areas where tiny marine plants and corals flourish.
On color-enhanced satellite maps showing measurements of global ocean chlorophyll levels, these productive patches of ocean stand out as bright green or red spots, for example around the Galapagos Islands in the eastern Pacific.
But as you look west, chlorophyll levels fade like a comet tail, giving scientists little reason to look closely at scattered low-lying coral atolls farther west. The islands are easy to overlook because they are tiny, remote, and lie at the far left edge of standard global satellite maps that place continents in the center.
Karnauskas, a climate scientist, was working with WHOI coral scientist Anne Cohen to explore how climate change would affect central equatorial Pacific reefs.
When he changed the map view on his screen in order to see the entire tropical Pacific at once, he saw that chlorophyll concentrations jumped up again exactly at the Gilbert Islands on the equator. Satellite maps also showed cooler sea surface temperatures on the west sides of these islands, part of the nation of Kiribati.
"I've been studying the tropical Pacific Ocean for most of my career, and I had never noticed that," he said. "It jumped out at me immediately, and I thought, 'there's probably a story there.'"
So Karnauskas and Cohen began to investigate how the EUC would affect the equatorial islands' reef ecosystems, starting with global climate models that simulate impacts in a warming world.
Global-scale climate models predict that ocean temperatures will rise nearly 3oC (5.4oF) in the central tropical Pacific. Warmer waters often cause corals to bleach, a process in which they lose the tiny symbiotic algae that life in them and provide them with vital nutrition. Bleaching has been a major cause of coral mortality and loss of coral reef area during the last 30 years.
But even the best global models, with their planet-scale views and lower resolution, cannot predict conditions in areas as small as small islands, Karnauskas said.
So they combined global models with a fine-scale regional model to focus on much smaller areas around minuscule islands scattered along the equator. To accommodate the trillions of calculations needed for such small-area resolution, they used the new high-performance computer cluster at WHOI called "Scylla."
"Global models predict significant temperature increase in the central tropical Pacific over the next few decades, but in truth conditions can be highly variable across and around a coral reef island," Cohen said. "To predict what the coral reef will experience under global climate change, we have to use high-resolution models, not global models.
Their model predicts that as air temperatures rise and equatorial trade winds weaken, the Pacific surface current will also weaken by 15 percent by the end of the century. The then-weaker surface current will impose less friction and drag on the EUC, so this deeper current will strengthen by 14 percent.
"Our model suggests that the amount of upwelling will actually increase by about 50 percent around these islands and reduce the rate of warming waters around them by about 0.7oC (1.25oF) per century," Karnauskas said.
A handful of coral atolls on the equator, some as small as 4 square kilometers (1.54 square miles) in area, may not seem like much. But Karnauskas's and Cohen's results say waters on the western sides of the islands will warm more slowly than at islands 2 degrees (or 138 miles) north and south of the equator that are not in the way of the EUC. That gives the Gilbert Islands a significant advantage over neighboring reef systems, they said.
"While the mitigating effect of a strengthened Equatorial Undercurrent will not spare the corals the perhaps-inevitable warming expected for this region, the warming rate will be slower around these equatorial islands, which may allow corals and their symbiotic algae a better chance to adapt and survive," Karnauskas said. If the model holds true, then even if neighboring reefs are hard hit, equatorial island coral reefs may well survive to produce larvae of corals and other reef species. Like a seed bank for the future, they might be a source of new corals and other species that could re-colonize damaged reefs.
"The globe is warming, but there are things going on underfoot that will slow that warming for certain parts of certain coral reef islands," said Cohen.
"These little islands in the middle of the ocean can counteract global trends and have a big impact on their own future, which I think is a beautiful concept," Karnauskas said.
"The finding that there may be refuges in the tropics where local circulation features buffer the trend of rising sea surface temperature has important implications for the survival of coral reef systems," said David Garrison, program director in the National Science Foundation (NSF)'s Division of Ocean Sciences, which funded the research.

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Climate Models



Greenhouse gas concentrations in the atmosphere will increase during the next century unless greenhouse gas emissions decrease substantially from present levels. Increased greenhouse gas concentrations are very likely to raise the Earth's average temperature, influence precipitation and some storm patterns as well as raise sea levels (IPCC, 2007). The magnitude of these changes, however, is uncertain.
The amount and speed of future climate change will ultimately depend on:
Whether greenhouse gases and aerosol concentrations increase, stay the same or decrease.
How strongly features of the climate (e.g. temperature, precipitation and sea level) respond to changes in greenhouse gas and aerosol concentrations.
How much the climate varies as a result of natural influences (e.g. from volcanic activity and changes in the sun’s intensity) and its internal variability (referring to random changes in the circulation of the atmosphere and oceans).












Climate Models


Virtually all published estimates of how the climate could change in the future are produced by computer models of the Earth’s climate system. These models are known as general circulation models (GCMs). According to the IPCC (2007):
“[C]onfidence in models comes from their physical basis, and their skill in representing observed climate and past climate changes. Models have proven to be extremely important tools for simulating and understanding climate, and there is considerable confidence that they are able to provide credible quantitative estimates of future climate change, particularly at larger scales. Models continue to have significant limitations, such as in their representation of clouds, which lead to uncertainties in the magnitude and timing, as well as regional details, of predicted climate change. Nevertheless, over several decades of model development, they have consistently provided a robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases.”
It is important to recognize that projections of climate change in specific areas are not forecasts comparable to tomorrow’s weather forecast. Rather, they are hypothetical examples of how the climate might change and usually contain a range of possibilities as opposed to one specific high likelihood outcome.