by Dana Nuccitelli, via Skeptical Science

There is a new myth circulating in the climate contrarian blogosphere and mainstream media that a figure presented in the “leaked” draft Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report shows that the planet has warmed less than previous IPCC report climate model simulations predicted. 

Tamino at the Open Mind blog and Skeptical Science’s own Alex C have done a nice job refuting this myth.  We prefer not to post material from the draft unpublished IPCC report, so refer to those links if you would like to see the figure in question.

In this post we will evaluate this contrarian claim by comparing the global surface temperature projections from each of the first four IPCC reports to the subsequent observed temperature changes.  We will see what the peer-reviewed scientific literature has to say on the subject, and show that not only have the IPCC surface temperature projections been remarkably accurate, but they have also performed much better than predictions made by climate contrarians (Figure 1).

Figure 1: IPCC temperature projections (red, pink, orange, green) and contrarian projections (blue and purple) vs. observed surface temperature changes (average of NASA GISS, NOAA NCDC, and HadCRUT4; black and red) for 1990 through 2012.

1990 IPCC FAR

The IPCC  First Assessment Report (FAR) was published in 1990.  The FAR used simple global climate models to estimate changes in the global mean surface air temperature under various CO2 emissions scenarios.  Details about the climate models used by the IPCC are provided in Chapter 6.6 of the report.

The IPCC FAR ran simulations using various emissions scenarios and climate models. The emissions scenarios included business as usual (BAU) and three other scenarios (B, C, D) in which global human greenhouse gas emissions began slowing in the year 2000.  The FAR’s projected BAU greenhouse gas (GHG) radiative forcing (global heat imbalance) in 2010 was approximately 3.5 Watts per square meter (W/m2).  In the B, C, D scenarios, the  projected 2011 forcing was nearly 3 W/m2.  The actual GHG radiative forcing in 2011 was approximately 2.8 W/m2, so to this point, we’re actually closer to the IPCC FAR’s lower emissions scenarios.

As shown in Figure 2, the IPCC FAR ran simulations using models with climate sensitivities (the total amount of global surface warming in response to a doubling of atmospheric CO2, including amplifying and dampening feedbacks) corresponding to 1.5°C (low), 2.5°C (best), and 4.5°C (high).  However, because climate scientists at the time believed a doubling of atmospheric CO2 would cause a larger global heat imbalance than today’s estimates, the actual climate sensitivities were approximately 18% lower (for example, the ‘Best’ model sensitivity was actually closer to 2.1°C for doubled CO2).

Figure 2: IPCC FAR projected global warming in the BAU emissions scenario using climate models with equilibrium climate sensitivities of 1.3°C (low), 2.1°C (best), and 3.8°C (high) for doubled atmospheric CO2

Figure 3 accounts for the lower observed GHG emissions than in the IPCC BAU projection, and compares its ‘Best’ adjusted projection with the observed global surface warming since 1990.

Figure 3: IPCC FAR BAU global surface temperature projection adjusted to reflect observed GHG radiative forcings 1990-2011 (blue) vs. observed surface temperature changes (average of NASA GISS, NOAA NCDC, and HadCRUT4; red) for 1990 through 2012.

FAR Scorecard

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Ultra-conservative report still concludes sea level rise could reach 6 inches a decade by century’s end! Deniers duped by leaker’s blunder.

Figure SPM.6.a. Warming in two IPCC scenarios reveals humanity’s choice. With aggressive action to reduce greenhouse gas emissions (RCP 2.6 with 443 ppm of CO2 in 2100), warming is modest and adaptation is plausible. With continued inaction (RCP 8.5 with 936 ppm in 2100), warming is a catastrophic and unmanageable 10°F over much of Earth’s habited and arable land — and more than 15°F over the Arctic. This projection ignores many key amplifying feedbacks, such as the release of permafrost carbon, which would likely lead to far greater warming.

The draft 2013 Fifth Assessment report of the Intergovernmental Panel on Climate Change leaked this week makes clear inaction on climate change would be devastating to modern civilization. The report finds that the human fingerprint on climate has grown more obvious, concluding “it is virtually certain” the energy imbalance that causes global warming “is caused by human activities, primarily by the increase in CO2 concentrations. There is very high confidence that natural forcing contributes only a small fraction to this imbalance.”

Yes, I know, the easily-duped deniers and their media stooges have reported the opposite is true, that solar forcing has been a significant driver of recent warming, but the deniers are as likely to be right as the flat earthers. The only question is why anyone still listens to them. I’ll repost a debunking of their nonsense below.

The draft Summary for Policymakers (the only thing 99% of people will ever read) finds:

It is extremely likely [">95% probability"] that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s. There is high confidence ["About 8 out of 10 chance"] that this has caused large-scale changes in the ocean, in the cryosphere, and in sea level in the second half of the 20th century. Some extreme events have changed as a result of anthropogenic influence.

That multiply-hedged morass is pretty much the mildest statement that could possibly be made. A December 2011 study found it’s “Extremely Likely That at Least 74% of Observed Warming Since 1950″ was manmade; it’s highly likely all of it was (see Figure 1 below).

For me, the leaked draft, which has not yet been peer reviewed — and thus still has time to be watered down yet more – underscores how pointless the IPCC has become. Like the 4th assessment before it, this ultra-conservative and instantly obsolete report ignores the latest science — see “Fifth Assessment Report Will Ignore Crucial Permafrost Carbon Feedback!” Note that including the permafrost feedback would probably make the RCP8.5 scenario in the top figure as much as 1.5°F warmer!

And like the AR4, the AR5 scenarios low-ball future impacts — “Arctic sea ice area is projected to decrease by 28% for September” for the 2016–2035 period vs. 1986–2005. Seriously IPCC, a 28% drop is the scenario your touting? In fact, as we have reported, many experts warn of “Near Ice-Free Arctic In Summer” in a decade if recent ice volume trends continue.

Even so, the uber-conservative AR5 draft makes clear to anyone who reads between the lines that inaction would be suicidal for humanity, with devastating warming and sea level rise that could hit a half a foot a decade by 2100. How precisely does one adapt to that?

Indeed, the report guts the one remaining myth of those who downplay future impacts, that clouds would act as a negative (or weakening) feedback. It finds:

The net radiative feedback due to all cloud types is likely positive.

But the report fails to clearly spell out what the recent science says about inaction — for that you might try “An Illustrated Guide to the Science of Global Warming Impacts” or the recentWorld Bank report, which warned “A 4°C [7°F] World Can, And Must, Be Avoided” To Avert “Devastating” Impacts.

So I can’t see why AR5 would motivate anyone to act more than AR4 and thus I see little real-world value in the entire effort — see my November 2007 post, “Absolute MUST Read IPCC Report: Debate over, further delay fatal, action not costly“! Plus ça change, plus c’est la même chose.

Once again, the authors twist themselves in pretzels to over-hedge every statement with their precise (but inaccurate!) terminology. And so we learn in the draft Summary for Policymakers (SPM):

It is very likely that the Arctic sea ice cover will continue to shrink and thin in the course of the 21st century as global temperature rises.

No, really, it is “very likely” — “> 90% probability” — which I guess means, what, that the IPCC  seriously thinks there is an up to 10% chance Arctic sea ice cover will stop shrinking and thinning???

Observations and analysis of drought make clear it is already intensifying in many key regions thanks to global warming — see “NOAA Bombshell: Human-Caused Climate Change Already a Major Factor in More Frequent Mediterranean Droughts” and “Study: Global warming is driving increased frequency of extreme wet or dry summer weather in southeast, so droughts and deluges are likely to get worse.” But all AR5 can muster up for the probability of future “increases in frequency and/or intensity of drought” is “Likely [> 66% probability] in some regions” — which I guess means the IPCC thinks there is 1 in 3 chance it won’t happen anywhere! How could that be with the kind of warming we will see in the RCP8.5 scenario, which, it must be added is really just  business as usual emissions and far from the worst-case?

In any case, most climate scientists expect considerably higher sea level rise, especially if we don’t act. That’s what the recent literature says — see “Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100” and “JPL bombshell: Polar ice sheet mass loss is speeding up, on pace for 1 foot sea level rise by 2050.”

Finally, if you read the denier blogs or columnists — and if so, you have no one to blame but yourself — you’ve probably heard something about how the IPCC finds cosmic rays are a major climate driver. In fact, the SPM finds:

Cosmic rays enhance aerosol nucleation and cloud condensation nuclei production in the free troposphere, but there is high confidence that the effect is too weak to have any significant climatic influence during a solar cycle or over the last century.

For debunkings of the latest denier spin, see here and here and especially here, which has an interview with the lead author of the key draft chapter.

Below I’m reposting a Skeptical Science piece on the subject.

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A key reason the Intergovernmental Panel on Climate Change keeps issuing instantly irrelevant reports is that it keeps ignoring the latest climate science. We have known for years that perhaps the single most important carbon-cycle feedback is the melting of the permafrost.

Yet a must-read new United Nations Environment Programme report, “Policy Implications of Warming Permafrost” reports this jaw-dropping news:

The effect of the permafrost carbon feedback on climate has not been included in the IPCC Assessment Reports. None of the climate projections in the IPCC Fourth Assessment Report include the permafrost carbon feedback (IPCC 2007). Participating modeling teams have completed their climate projections in support of the Fifth Assessment Report, but these projections do not include the permafrost carbon feedback. Consequently, the IPCC Fifth Assessment Report, due for release in stages between September 2013 and October 2014, will not include the potential effects of the permafrost carbon feedback on global climate.

Here’s why that is head-exploding.

Carbon emission (in billions of tons of carbon a year) from thawing permafrost [from Schaefer et al, 2011]

Back in 2005, before the IPCC’s Fourth Assessment, a major study (subs. req’d) led by NCAR climate researcher David Lawrence, found that virtually the entire top 11 feet of permafrost around the globe could disappear by the end of this century. Using the first “fully interactive climate system model” applied to study permafrost, the researchers found that if we tried to stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million.

That matters because the permafrost permamelt contains a staggering “1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which would be released as methane.  Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 to 100 times as potent over 20 years!

A 2008 study by leading tundra experts, “Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss,” concluded:

We find that simulated western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than secular 21st century climate-change trends. The accelerated warming signal penetrates up to 1500 km inland….

Considering that 2012 saw a new record low in Arctic sea ice cover — and that Arctic ice loss is occurring many decades faster than climate models had projected —  you would think that climate scientists would want to incorporate this accelerated warming and the related tundra melt in their models.

The literature, of course, has continued to refine estimates of permafrost loss from various emissions scenarios. The graph above comes from a study published in February 2011, “Amount and timing of permafrost carbon release in response to climate warming,” which concluded soberly:

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The world’s climate scientists agree that humanity is poisoning the weather with fossil fuel pollution, making extreme weather more dangerous and deadly. The cavalcade of catastrophe of recent years — epic floods, heat waves, droughts, and storms — is only a foretaste of our planet’s future, because of the unceasing buildup of carbon pollution from the burning of oil, coal, and other fossil fuels. A special report from the Intergovernmental Panel on Climate Change summarizes some of the latest scientific findings, which paint a dire picture of increasing disaster for a largely unprepared civilization:

“We need to be worried,” said one of the study’s lead authors, Maarten van Aalst, director of the International Red Cross/Red Crescent Climate Centre in the Netherlands.

The report calls for mobilization in climate resilience, in particular approaches that reduce the exposure to climate disasters while also improving economic well-being and lowering pollution. Areas that need focus include systems that warn people of impending disasters; changes in land use planning; sustainable land management; ecosystem management; improvements in health surveillance, water supplies, and drainage systems; development and enforcement of building codes; and better education and awareness.

Climate disasters strike the rich and poor very differently. In short, climate disasters harm the economies of developed countries, but kill the people in developing countries. From 1970 to 2008, over 95 percent of natural-disaster-related deaths occurred in developing countries. For some, the only risk management from disasters like sea level rise and drought will be relocation.

Scientists recently found that day-to-day weather has grown increasingly erratic and extreme, with significant fluctuations in sunshine and rainfall affecting more than a third of the planet.

In a new, bi-weekly video report, BBC reporter Martine Croxall reviews the most recent extreme weather from around the globe. In the first episode of this Vestas-sponsored venture, she discusses the freak polar hurricane, flash floods in Italy, Snowtober, and the Thailand floods:

Losses from climate disasters are already high, running at as much as $200 billion a year, said Michael Oppenheimer of Princeton University, a study author. “Global warming is increasing the risk of disaster and already makes dealing with several types of disaster, like heat waves, more difficult. The risk will become greater as the future gets hotter,” he said. “Governments are not doing a good job now protecting us from disaster in the current climate.”

A USA Today (not IPCC) chart emphasizes the risk of drought in heavily populated areas.

The IPCC Special Report “Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)” is now online.  I had seen the previous draft and the changes to it, so I knew that it was a big missed opportunity, as I explained here.

UPDATE:  Dr. Richard Klein offers a defense of the IPCC process in the comments of my previous post (here).

Even so, since the media hasn’t been spending much time connecting the dots between extreme weather and climate change, the report has garnered some headlines:

• Report: Climate change worsens extreme weather events (USA Today)
• Extreme weather to worsen with climate change: IPCC (Reuters)
• Extreme weather will strike as climate change takes hold, IPCC warns; Heavier rainfall, storms and droughts could wipe billions off economies and destroy lives, says report by 220 scientists (UK Guardian).

There is definitely some good material in the report (I’ll do a separate post on that).  We should all appreciate the hard work that a great many scientists put into this report.  I’ve been highly supportive of IPCC scientists over the years, pushing back against the attacks by the deniers and confusionists — even as I have been critical of the IPCC process that tends to water down even the most obvious conclusions.

For instance, the report states:

It is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes will occur in the 21st century on the global scale. It is very likely that the length, frequency and/or intensity of warm spells, or heat waves, will increase over most land areas.

Virtually certain means “99-100% probability” while very likely means “90-100% probability.”  Is there really as much as a 10% chance that the length, frequency and/or intensity of warm spells, or heat waves, will NOT increase over most land areas over the next 90 years?

Then we have this line:

It is very likely that mean sea level rise will contribute to upward trends in extreme coastal high water levels in the future.

C’mon guys and gals.  You couldn’t put a “virtually certain” on that?  Note that the sentence is already hedged with “will contribute” and “upward trends” and even the vague “in the future.”  Precisely how could mean sea level rise — even sticking with the lowball estimate from the 2007 report — have as much as a 10% chance of NOT contributing toward an upwards trend in extreme coastal high level waters sometime in the future.

So you can see the effect of the IPCC process that waters down even the most innocuous conclusions.  And by the way, since this is a 2011 report, it ought to base such statements on the recent literature of sea level rise, which is considerably higher than the 2007 estimate (see the discussion in “Scientists withdraw low-ball estimate of sea level rise“).

My biggest problem with the report remains the short shrift it gives to the vast literature on drought that I reviewed in my recent Nature article.  As I wrote, “Feeding some 9 billion people by mid-century in the face of a rapidly worsening climate may well be the greatest challenge the human race has ever faced.”

You can see from the chart above that USA Today (and Jeff Masters, who helped put it together) figured out that drought may be the biggest extreme weather danger in that it affects 5 heavily populated areas.

Reuters, in its story, states what should be obvious:

Droughts, perhaps the biggest worry for a world with a surging population to feed, were also expected to worsen.

The 29-page report itself has quite little on droughts, and the word “agriculture” appears only once in the main text, but it does have this blockbuster chart:

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UPDATE:  Andy Revkin’s comment (here) may be the single most head-exploding and revisionist thing he has ever written. I reply.  The adaptation expert, Dr. Richard Klein, offers a defense of the IPCC process in the comments (here).

Fortunately, the public already understands that global warming makes extreme weather more severe, as new polling reveals:

September polling by ecoAmerica found that 57% of Americans already understand “If we don’t do something about climate change now, we can end up having our farmland turned to desert.”  Duh:

The Palmer Drought Severity Index on a “moderate” warming path (via NCAR, click to enlarge). “A reading of -4 or below is considered extreme drought.” During the 1930s Dust Bowl, the PDSI spiked briefly to -6 but rarely exceeded -3.  We probably can’t stop this, but we can avert far, far worse post-2050 (see below).

The UN’s Intergovernmental Panel on Climate Change is coming out Friday with its umpteenth watered down report on climate science, in this case on extreme weather.  The thing to remember about IPCC reports is that pretty much everyone involved has to sign off on every word, so it is inevitably a least common denominator document.

The actual scientific literature from 2011 is far more useful than this report — see “Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming” and “NOAA Study Finds Human-Caused Climate Change Already a Major Factor in More Frequent Mediterranean Droughts.”  I will provide the links to as many recent studies as possible in this post.

Indeed we already know from a major 2011 study that “human-induced increases in greenhouse gases have contributed to the observed intensification of heavy precipitation events found over approximately two-thirds of data-covered parts of Northern Hemisphere land areas.”  As predicted, the warming has put more water vapor in the air, making deluges more intense.  Climatologist Kevin Trenberth explains:

There is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms,

Obviously, since it’s getting hotter, we’re worsening extreme heat waves — both in intensity and duration and scale (the area the heat wave covers).  For the same reason, we know humans are making droughts worse — in intensity, duration, and scale.  The earlier snow melts also makes summer droughts worse.

Actual observations reveal that since 1950, the global percentage of dry areas has increased by about 1.74% of global land area per decade (see here).  Heck, our best scientists are already using global warming to help them predict dangerous extreme weather (see “USGS Expert Explains How Global Warming Likely Contributes to East Africa’s Brutal Drought“).

The reinsurance industry understands all this (see Munich Re: “The only plausible explanation for the rise in weather-related catastrophes is climate change”).

Again, much if not most of the public appear to have a better sense of what’s happening right now than you’ll find in the summaries of a typical IPCC report, to go by Yale’s 2011 polling and the September poll from ecoAmerica quoted at the top, which also found:

69% of Americans Know “Weather Conditions (Such as Heat Waves and Droughts) Are Made Worse by Climate Change”

The American public can’t miss the extreme weather because it is everywhere now and increasingly off the charts (see “A New Record: 14 U.S. Billion-Dollar Weather Disasters in 2011“) and links below.

Of course, what’s to come is the real issue, since we still have control over that.  We’re facing 5 to 10 times the warming this century that we’ve seen in the past half century.

Unfortunately, the IPCC continues to conflate uncertainty in future emissions of greenhouse gases with uncertainty in the climate’s sensitivity to those emissions.  This means they present a very large range of possible overall impacts — and that allows the deniers to trumpet the low range with their powerful fossil-fuel-funded megaphone and induces the media to provide “balance” in their stories between the mid-range and the low range.

The reality is we are on the highest emissions trends (see “Biggest Jump Ever in Global Warming Pollution in 2010 means “levels of greenhouse gases are higher than the worst case scenario outlined by climate experts just four years ago”).  And the latest science and observation points towards the high end of the climate’s sensitivity (see Journal of Climate: New cloud feedback results “provide support for the high end of current estimates of global climate sensitivity”).

Most climate scientists know what is coming if we don’t act quickly– and more and more are shedding their reticence to speak out, even if that is not yet reflected in bland, least-common-denominator IPCC reports (see Lonnie Thompson on why climatologists are speaking out: “Virtually all of us are now convinced that global warming poses a clear and present danger to civilization”).

And as long as the deniers, inactivists and climate ignorati rule the debate, inaction is assured, which means that we are risking extreme weather beyond imagination, extreme events on top of an average warming this century that could hit 13-18°F over most of U.S. and 25°F in the Arctic:

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The Kyoto Protocol is in shambles, greenhouse pollution is at record levels, and climate disasters are growing in frequency and intensity.

To preserve the promise of civilization, we must start anew.

Twenty years ago, the world agreed that the increase in greenhouse gas emissions needs to be reversed as quickly as possible, or dangerous and potentially irreversible degradation of the global climate system would begin in about twenty years.

Those twenty years have passed, and now the world must mobilize to eliminate global warming pollution and defend humanity against the dangerous climate change that is now happening.

The existing global framework to address the threat of global warming — governmental, academic, scientific, economic, societal — is two decades old. The world’s top climate scientists drove the formation, in 1988, of the Intergovernmental Panel on Climate Change by the World Meteorological Organization and the United Nations. Following the first IPCC climate change assessment report in 1990, representatives of the planet’s governments gathered in Rio de Janeiro in 1992 to establish a framework convention for addressing climate change — called, naturally enough, the United Nations Framework Convention on Climate Change. That framework, ratified by all the world’s governments, including the United States, has guided civilization’s collective effort to address the threat of greenhouse emissions to the present day. As expressed in the UNFCCC:

The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

Despite their best efforts, those committed to achieving the objectives of the convention failed. The 1990 First Assessment Report correctly warned that “irreversible change in the climate” could come by 2000. Permafrost melt, sea level rise, species extinction, glacial retreat and disappearance, and other systemic impacts have transformed our planet for the worse. The degraded climate is now causing the decline of ecosystems, degradation of food production, and economic instability around the globe. Left unchecked, global warming is increasingly likely to solve the emissions problem through the collapse of industrial civilization.

So what can be done?

The necessary elements for defending civilization in a more dangerous, rapidly changing world all exist. Insurance companies are reconfiguring their policies as seas rise and disasters increase. Hedge funds are developing new financial instruments to handle the effects of climate instability. City planners are examining the security of transit and utility systems. Military officials are drawing up new war scenarios. Scientists and entrepreneurs are inventing, refining, and deploying technologies to sustainably power civilization. Activists are putting their freedom on the line to challenge the forces of inaction. But these efforts are haphazard and uncoordinated. They are insufficient to ensure that the human rights of life, liberty, and the pursuit of happiness are realized on our polluted planet.

The missing piece, often described euphemistically as “political will,” involves a complete rethinking of the threat of global warming. Most Americans see global warming as a real problem, but one that is distant in time and space: that will only affect their children or grandchildren, one that will affect far reaches of the planet first and foremost. That misunderstanding is utterly natural, since that is the presumption of the existing framework, reinforced by the rhetoric and actions of political leaders like President Barack Obama. The greatest culpability, of course, lies in the immoral acts of powerful polluters and their allies to deny the threat entirely.

The new climate framework needs to be built on the following principles:

– Humanity is responsible for climate disasters.

– Climate change is not only a future threat but an active enemy to societal progress.

– All investments must take into account the reality of increasing uncertainty and risk as the climate system becomes more unstable.

– All existing infrastructures — physical, legal, economic, political, cultural — need to be re-examined for resilience in our changing world.

ThinkProgress Green and Climate Progress will be reporting on the efforts of this generation of humanity, and of the great democratic experiment of the United States of America, to build this new framework.