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Report: IPCC Underestimates Climate Risks

By Glenn Scherer, The Daily Climate

Across two decades and thousands of pages of reports, the world's most authoritative voice on climate science has consistently understated the rate and intensity of climate change and the danger those impacts represent, say a growing number of studies on the topic. 

This conservative bias, say some scientists, could have significant political implications, as reports from the group – the U.N. Intergovernmental Panel on Climate Change – influence policy and planning decisions worldwide, from national governments down to local town councils.

Residents of Tumana, in the Philippines, clean up after a 2009 typhoon. The country was hit with another devastating typhoon in December, 2012. An assessment of projections by the UN Intergovernmental Panel on Climate Change finds the group has consistently understated the risk posed by climate change. Credit: Audrey N. Carpio/flickr.

As the latest round of United Nations climate talks in Doha wrap up this week, climate experts warn that the IPCC's failure to adequately project the threats that rising global carbon emissions represent has serious consequences: The IPCC’s overly conservative reading of the science, they say, means governments and the public could be blindsided by the rapid onset of the flooding, extreme storms, drought, and other impacts associated with catastrophic global warming.

"We're underestimating the fact that climate change is rearing its head," said Kevin Trenberth, head of the climate analysis section at the National Center for Atmospheric Research (NCAR) and a lead author of key sections of the 2001 and 2007 IPCC reports. "And we're underestimating the role of humans, and this means we're underestimating what it means for the future and what we should be planning for." 

Underplaying the intensity

A comparison of past IPCC predictions against 22 years of weather data and the latest climate science find that the IPCC has consistently underplayed the intensity of global warming in each of its four major reports released since 1990.

The drastic decline of summer Arctic sea ice is one recent example: In the 2007 report, the IPCC concluded the Arctic would not lose its summer ice before 2070 at the earliest. But the ice pack has shrunk far faster than any scenario scientists felt policymakers should consider; now researchers say the region could see nearly ice-free summers within 20 years.

The IPCC concluded the Arctic would not shed most of its summer sea ice cover before 2070 at the earliest. But the sea ice pack has shrunk far faster than most scenarios scientists felt policymakers should consider; now researchers say the region could see largely ice-free summers within 20 years. Credit: NASA.

Sea-level rise is another. In its 2001 report, the IPCC predicted an annual sea-level rise of less than 2 millimeters per year. But from 1993 through 2006, the oceans actually rose 3.3 millimeters per year, more than 50 percent above that projection. The IPCC did note, however, that its sea level rise projections did not take into account the contribution of the melting of Greenland and the West Antarctic ice sheet, since there was conflicting evidence at the time.

Some climate researchers also worry that recent institutional changes could accentuate the organization's conservative bias in the fifth IPCC assessment, to be released in parts starting in September 2013.

The tendency to underplay climate impacts needs to be recognized, conclude the authors of a recent paper exploring this bias. Failure to do so, they wrote in their study published last month in the journal Global Environmental Change, "could prevent the full recognition, articulation and acknowledgement of dramatic natural phenomena that may in fact be occurring."

Conservative bias

The conservative bias stems from several sources, scientists say. Part can be attributed to science's aversion to drama and dramatic conclusions: So-called outlier events — results at far ends of the spectrum — are often pruned. Such controversial findings require years of painstaking, independent verification. 

Yet some events in nature are dramatic, conclude University of California, San Diego, history and science professor Naomi Oreskes and Princeton University geosciences professor Michael Oppenheimer, co-authors of the study looking at the IPCC's bias. "If the drama arises primarily from social, political or economic impacts," they wrote, "then it is crucial that the associated risk be understood fully, and not discounted.”

IPCC Vice-Chair Jean-Pascal van Ypersele countered that "the mandate of IPCC is to achieve consensus" and to reflect the "full diversity of views that are scientifically valid." He conceded that by requiring teams of authors to agree upon a report’s text, the IPCC process is inherently conservative. Getting the balance right, he said in an e-mail, is "not always easy."

Oreskes, Oppenheimer and their co-authors argue the conservative bias pervades all of climate science. 

But the underestimation by the IPCC is particularly worrisome, scientists say, because the organization is charged specifically with advising policy makers on the most relevant, accurate climate science.

Current science

Established in 1988 by the United Nations, the IPCC does no original climate science research. Its role is to review current science from around the world, then synthesize and summarize that data within comprehensive reports meant for policymakers.

Michel Jarraud, Secretary-General of the World Meteorological Organization. Credit: UN Office for Disaster Risk Reduction, via Facebook.

Such assessments typically take five to seven years to complete in a slow, bureaucratic process: Thousands of scientists from around the globe, working as unpaid volunteers, first sift through the scientific literature, identifying trends and writing a draft report. That draft is reviewed and thoroughly revised by other scientists. Then a summary for policymakers, condensing the science even further, is written and subjected to a painstaking, line-by-line revision by representatives from more than 100 world governments — all of whom must approve the final summary document. 

IPCC's four assessments — massive, multi-tome volumes released in 1990, 1995, 2001 and 2007 — are considered the gold standard in climate science. The fourth report earned both intense criticism from climate skeptics and the honor of the 2007 Nobel Peace Prize, shared with former Vice President Al Gore.

Yet since that 2007 assessment, numerous observations and studies have shown that the speed and ferocity of climate change are at the extreme edge or outpacing IPCC projections on many fronts, including carbon emissions, temperature rise, continental ice-sheet melt, Arctic sea ice decline, and sea level rise (see sidebar).

Pattern of under-projection

The pattern, said Oreskes in an interview, is under- rather than over-projection. "These data simply do not support the allegations by skeptics that scientists have been alarmists," she said.

One example: In November, scientists at NCAR in Boulder, Colo., took a closer look at the computer models underpinning most climate predictions and concluded future warming is likely to be on the high side of climate projections.

Another example: This summer, NASA climatologist James Hansen co-authored an analysis of recent extreme weather across the globe. Hansen's team arrived at a strikingly different conclusion from an IPCC special assessment on the topic released just months earlier.

NASA climatologist James Hansen co-authored an analysis of recent extreme weather across the globe. Hansen's team arrived at a strikingly different conclusion from an IPCC special assessment on the topic released just months earlier. Credit: NASA Goddard.

The Hansen study, published in August in the journal Proceedings of the National Academy of Sciences, concluded that rapid climate change over the past 30 years has loaded the dice in favor of extreme weather. The chance of extreme summer heat is now 13 percent higher than in 1980, the report found. Record heat waves seen by Europe in 2003, Russia in 2010, and Texas in 2011 would have been much less likely without human-caused global warming, it concluded. 

Hansen's conclusion contrasted sharply with the hedging in the IPCC special assessment on extreme weather, published in March, 2012: "Confidence in projecting changes in the direction and magnitude of climate extremes depends on many factors," the report's summary for policymakers began. "Even the sign of projected changes in some climate extremes over this time frame is uncertain."

IPCC scientist and Pennsylvania State University professor of meteorology Michael Mann, who was not involved in the March IPCC report, said the IPCC missed an opportunity to provide politicians with a clear picture of the extent of the climate crisis. "Many scientists felt that report erred by underplaying the degree of confidence in the linkage between climate change and certain types of severe weather, including heat wave severity, heavy precipitation and drought, and hurricane intensity,” he said.

Communication burden

Not all blame IPCC for failing to produce sufficient alarm with policymakers, however.

Andrew Dessler, professor of atmospheric sciences at Texas A&M University, sees no need for the IPCC to do anything differently. "The burden of communication falls on policymakers, not scientists," he said. Scientists are responsible for providing the hard data. It is up to policymakers to lead, connect the dots, and explain to the public the necessity of responding to global warming. 

But the consequences of a conservative bias by climate scientists can be significant, others like Oreskes note. A society blind to the full range of potential outcomes, particularly the most disruptive, can remain apathetic to the need for change, pushing hard decisions off into the future.

The melting Arctic ice pack may offer such an example. 

Scientists suspect that a diminished Arctic ice pack has the power to shift weather patterns across the Northern Hemisphere. Less sea ice, the hypothesis goes, leads to a warmer Arctic. This in turn can shift the jet stream, causing it to become wavier, and lead to more clogged weather patterns, like an atmospheric traffic jam, in which dry spells and heat waves are held in place so that they pound a single location for days, weeks or months. 

But with the ice supposed to stay intact until 2070 or later, this was largely a theoretical problem for the future. 

No longer: Summer sea ice in the Arctic hit a new low in 2012, and now some scientists say there is likely a link between that meltdown and the record-breaking drought that caused an estimated $28 billion in damage across the United States, as well as the soggy summer that left Britain drenched.

Even Hurricane Sandy has a potential Arctic tie-in, with researchers suggesting that the anomalous strong high pressure weather system over Greenland, forcing Sandy ashore in October, was influenced by the ice cap's decline. 

These events — and especially the rapidity with which they are occurring — were not foreseen by IPCC models.

Dismissed as outliers

Likewise, weather forecasters not associated with the IPCC, using short-term weather and climate forecast models, almost uniformly failed to predict the drought that gripped most of the United States this summer. The reason? The few computer models that did forecast a major drought were dismissed as outliers, according to a report by Climate Central, a science research and communication organization.

A house in Union Beach, N.J. that was damaged by Hurricane Sandy. Credit: UN Office for Disaster Risk Reduction, via Facebook.

"It's like going to a doctor," said Princeton's Oppenheimer. "When data is weak you ask your doctor for his or her best judgment.

"That is what IPCC is supposed to do." 

IPCC's Fifth Assessment will be released in four parts from September 2013 through September 2014. Reforms within the organization have resulted in a more demanding consensus process — one that may produce even greater caution in its conclusions, say several former senior IPCC authors. 

"The next report shows every sign of being even more conservative than the previous ones," said Trenberth. Instead of 10 lead authors per chapter, 14 or 15 scientists will have a say, making consensus-building harder. 

"That builds in more conservatism, caveats, and wiggle room," Trenberth said. 

IPCC's internal rules and deadlines have also been tightened, preventing the inclusion of some of the most up-to-date studies, he added. 

Input from contrarians

Penn State's Mann also feels that IPCC higher-ups, fearful of being attacked by climate skeptics, have "bent over backwards" to allow greater input from contrarians. "There's no problem in soliciting wide views that fairly represent … a peer group community," he said. "My worry is that they are stacking the deck, giving greater weight to contrarian views than is warranted by peer-reviewed literature."

There are indeed more authors for next year’s assessment — 831 as compared to about 500 for the 2007 report, said IPCC’s van Ypersele, “But there are many more chapters as well, because the scope of the fifth assessment is larger.” The resulting document, he said, will be “based on real science and not ideology.”

"Overall, the IPCC reports represent the best source of quality information on climate change," van Ypersele said.

'Nature of research'

Underestimates will continue to characterize climate projections, cautioned Richard Somerville, IPCC scientist and Professor Emeritus and Research Professor at Scripps Institution, "But that's the nature of research," as it constantly discovers new possibilities. 

Looking back at the 1950s when scientists first identified the climate problem, Somerville notes that the tone at the time "was not catastrophic at all, but rather curious to see how the climate system would react to a big spike in carbon dioxide emissions." Only over time did the full realization dawn on the scientific community that many of the consequences of climate change could be very serious and even catastrophic.

And that is what hasn't gotten across to the public, Somerville warned: a sense of urgency that, to most scientists, is now very clear. 

"This is an urgency that has nothing to do with politics or ideology," said Somerville. "This urgency is dictated by the biogeochemistry and physics of the climate system. We have a very short time to de-carbonize the world economy and find substitutes for fossil fuels." 

The Daily Climate is a nonprofit news service covering climate change, and a Climate Central content partner.


By Dan Thompson (Gresham, Oregon 97080)
on December 10th, 2012

Radio, data transmission, TV, sensors, remotes, satellites, locators, trackers, radar, dumb and smart cell phones, internet, lasers, i this and that and a growing list of other hand helds all create or utilize energy frequencies that permeate the atmosphere keeping it in a constant state of activity, aka: warmth, especially restricting cooling at night.  Denial has no impact on it impact but it does restrict our understanding of what is happening, in addition to nature and the gas comforter we wrap the Earth in.

Reply to this comment

By Dave (Basking Rudge, NJ 07920)
on December 10th, 2012

The IPCC has clearly served a very valuable function over the years and I hesitate to condemn it for paying lip service to politics. All institutions ‘suffer’ from some degree of politics. Yet this report suggests a degree of tainting that is disturbing. IMO it does us all a disservice for such a high-stakes institution to mix even an ounce of denier style “conservative” politics and science and then claim scientific objectivity. Somerville’s comments in this piece get to the heart of it.
In most other branches of science it would be frowned upon to take a valid prediction or projection and intentionally tone it down, ‘dilute’ or ignore it for non scientific reasons. And of course society would soon cease to function if people systematically ‘conservatively’ interpreted commonplace, commonsense warnings and predictions with all sorts of other mundane day-to-day things.

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By Lorin Thwaits (Phoenix, AZ)
on December 11th, 2012

Amazes me that anyone remains a denier in this day and age.  The “grand old party” with its ruse of conservatism is ironically the biggest consumer and waster of the environment, bent on destruction.  God I only hope with the next big storm or two people will actually come to their senses.

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By oaw (Houston, TX 77035)
on December 11th, 2012

how the climate system would react to a big spike in carbon dioxide emissions.

Spikes go up and then down.
What we are seeing is not a spike.
There is no indication that emissions will go down in any plan I have heard of.
And once emitted the removal time is measured in centuries not years!

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By Dan Miller (Orinda, CA 94563)
on December 11th, 2012

Dr. Hansen’s study shows a 5000% (50X) increase in Extremely Hot Summers, not 13%!  The percent of locations that had average summer temperatures higher than 3 standard deviations (“3-sigma”) above the baseline (1951-1980) mean was 0.2% in the baseline period and was 10% in the last decade (2001-2010).  Because of this 50X increase, the probability of a current 3-sigma heat wave (like to current Midwest heat wave) is due to natural causes is 1/49=2%.  The probability it is due to global warming is 49/50=98%!

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By EDpeak
on December 11th, 2012

Found this important post via the Daily News Digest on the ClimateProgress blog led by Joe Romm…but a different post on ClimateProgress is very relevant here:

“IPCC’s Planned Obsolescence: Fifth Assessment Report Will Ignore Crucial Permafrost Carbon Feedback!”
By Joe Romm on Dec 2, 2012 at 12:24 pm

Which I utrge people to find by google (not sure if links are ok here) Excerpt:

“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:

’ 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.’ “

I would add:
There is a lot of political pressure from China, the U.S., countries in the fossil-fuel rich Middle East and others (Canada and its Tar Sands, Australia too..) to water things down and one way that’s been done is to deliberately exclude warning people what is less than completely settled (but still very solid) science warning what appears to be happening - lower common denominator instead of Precautionary Principle. Doctors would never act this way (or if they did they would be condemned by the public) they would not “let me not even mention this to the patient at all since it’s not as well understood even though there is a lot of solid evidence for it and strong indications it may be happening in the patient’s body…so let me only mention what is agreed upno by ALL 10 doctors who studied the Xrays and lab blood tests…”  Insane not to include our best science and what is says about the thawing permafrost (or “perma”-frost)

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By Sigvaldi Ásgeirsson (320 Reykholt, Iceland)
on December 12th, 2012

Dear Mr./Ms!
I am native to Iceland. This island´s proximity to Greenland could have an unforseen impact on climate change. The reasoning goes as follows: There is scientific consensus amongst volcanologists, that the increasing rapidity of melting of Iceland´s glaciers, will unfortunately trigger a much higher frequency of volcanic eruptions in places still covered by thick ice. This has to do with the lighter weighting down of the Earth´s crust by thinning glaciers, especially that of Vatnajökull (and Mýrdalsjökull with the fearsome Katla volcano). Volcanic eruptions taking place under an icesheet and reaching up into the atmosphere are invariably mostly producing pumice and ashes and not lava streams. The fine grained ashes can be thrown far up into the atmosphere and carried off thousands of km, such as happend during the infamous Eyjafjallajökull eruption two and a half years ago and again during Grímsvötn eruption (under the Vatnajökull icesheet) about a year later. Although jetstreams would carry most of the ashes in the direction of Europe, some ashes can, be the wind direction from southeast to east, as it frequently is in this part of the world, be carried towards Greenland, since not all ashes reach high enough altitude to enter the jet stream belt. The ashes will have the same effect as sot, only on a larger scale, since the quantity is so great, as has been seen happening on the Icelandic glaciers after those two large ashproducing recent eruptions. This can have a big effect on the speed with which the Greenland icesheet might melt. Yet I am still sceptical as to whether a few degrees of warming will effectuate a reduction of the landice of Greenland, since such a large part of that huge glacier is so high above sealevel, that most precipitation on the glacier will still be in the solide phase. A warming climate might increase precipitation on the Greenland glacier, most of which would fall as snow. The same applies to the icesheet on the mainland of Antarctis. If however a recently existing technology for measuring the thickness of inland-icesheets shows that those two huge glacial areas have a diminishing icesheet as denominated in cubic km, then I´ll rest my case.
Yours sincerly, Sigvaldi Ásgeirsson.

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By Tamsen Miller (montana)
on December 14th, 2012

“These very senior people said we are likely to go on to 4-6 degree C but we just can’t be open about it.  That is going on all the time behind the scenes, that somehow we can’t tell the public”
Said by
Kevin Anderson, University of Manchester
during a talk, “Real clothes for the Emperor”
given at the Cabot institute annual lecture 2012, University of Bristol.
can be found on Youtube. 
very interesting lecture.  He tells more of the “truth” than do others.

also check out Naturebatslast,
blog by Guy Macpherson, he tells a lot of inconvenient truths as well.

“It is up to policymakers to lead, connect the dots, and explain to the public the necessity of responding to global warming. “
no wonder we don’t hear anything close to the truth.  The policy makers are interested only in the economy. not the environment.

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By Dan Thompson (Gresham, Oregon 97080)
on December 14th, 2012

And still everyone ignores a partner in the warming…that being the energy that permeates the atmosphere from our relentless and exploding wireless communication.  From radio and TV to i this and that, sensors, satellites and tablets galore we create or utilize that energy constructing a hot water bottle to put under the gas comforter we also weave.  Ignoring or denying things doesn’t make it go away, never has, never will.

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By Michael Masters (Tucson, Arizona 85716)
on December 16th, 2012

I would like to know why governments role in climate change is never discussed. The US, Russia and China have actively been trying to alter the world’s climate for decades. They have spent hundreds of billions of dollars and unleashed untold amounts of chemicasl and metals into the atmosphere. Are we to assume they have had no effect? A lot more than wireless devices and automobiles I am sure.

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