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Climate Projections More Confident, Dire From IPCC

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Manmade global warming is rapidly transforming the planet at rates that are unprecedented in human history, from melting Arctic sea ice to heating the land and seas and contributing to extreme weather events, concluded a new landmark climate report from the United Nations on Friday.

The study, the fifth major assessment from the U.N. Intergovernmental Panel on Climate Change (IPCC), projects a bleak future of rising sea levels, more intense and frequent heat waves, destructive droughts and floods, as well as more acidic oceans that will be less capable of supporting marine life.

Global average surface warming in deg Celsius during the past century.
Click image to enlarge. Credit: IPCC.

The report serves as yet another warning that without dramatic and rapid cuts in emissions of global greenhouse gas emissions, primarily emissions of carbon dioxide (CO2), the consequences of climate change could be disastrous in many parts of the world.

“Climate change challenges the two primary resources of humans and ecosystems — land and water. In short, it threatens our planet, our only home,” said Thomas Stocker, a climate scientist at the University of Bern in Switzerland and co-lead author of the IPCC’s Working Group I, which released its report on Friday at a press conference in Stockholm.

The report found that each of the past three decades has been warmer than all preceding decades since 1850, and the period from 1983-2012 was “likely” the warmest 30-year period of the past 1,400 years in the Northern Hemisphere.

The study projects that global surface temperatures are likely to exceed 2.7°F above preindustrial levels by the end of the century and will likely range from 0.54°F to 8.64°F above 1986-2005 levels, depending on greenhouse gas emissions.

At the U.N. climate summit in Copenhagen in 2009, global leaders committed to containing global warming to under 3.6°F above pre-industrial levels. The new report illustrates that goal is now unfeasible.

Friday’s study said that to stay below 3.6°F, global carbon emissions would have to remain below 1 trillion metric tons. According to Stocker, 54 percent of that carbon budget has already been emitted. If global warming continues unabated, the consequences are grave, from rising sea levels to extensive melting of the polar ice sheets.

“Humankind has a choice on which scenario we will face in the coming 100 years or so. It depends crucially on how much carbon dioxide will be emitted in the future,” he said.

Each of the past three decades has been among the warmest in the instrument record, and likely the Northern Hemisphere's warmest in more than 1,000 years, the IPCC report found. 
Click image to enlarge. Credit: Climate Central

The report was released in the same city that hosted the world’s first global environmental conference in 1972, and the report is the first in a series of three reports to be released through 2014 as part of the IPCC’s Fifth Assessment Report.

“The world’s eyes are on Stockholm today,” said U.N. Secretary General Ban Ki-moon. “The heat is on . . . now we must act.”

The study echoes conclusions found in both the IPCC’s Fourth Assessment Report in 2007 and in numerous individual studies since, including the finding that Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will continue to decrease, along with global glacier volume. It includes more specific details on sea level rise, the sensitivity of the climate system to increasing amounts of CO2, and the importance of cumulative CO2 emissions, among other findings.

The report states with unprecedented confidence — at least 95 percent certainty — that humans have “been the dominant cause of the observed warming since the mid-20th century.” That is an increase in certainty from 2007’s report, in which scientists said there was at least 90 percent confidence in this conclusion.

The increase in confidence, scientists said, stems from multiple lines of evidence of a warming planet, from increasing ocean heat content to melting Arctic sea ice, which are all consistent with warming due largely to rising amounts of greenhouse gases. 

“The evidence for human influence has grown since the Fourth Assessment Report,” said Achim Steiner, executive director of the U.N. Environment Program.

The report found that atmospheric concentrations of greenhouse gases, such as CO2 and methane, have increased to levels unprecedented in at least the past 800,000 years, and that the ocean has absorbed about 30 percent of the manmade emissions of CO2, causing waters to become more acidic and endangering some marine life.

For Friday’s report, climate researchers and government representatives combed through a draft to approve each word, sentence, and paragraph of the document, finishing their work only a few hours before the press conference began. There were few substantive changes made between the draft summary and the completed version, with some edits made to clarify what is known about a recent slowdown in the rate of warming, which most climate scientists regard as a temporary fluctuation that will not last much longer.

The IPCC's projections for global mean sea level rise, depending on the amount of greenhouse gases in the atmosphere.
Click image to enlarge. Credit: IPCC.

Stocker told reporters that "110 governments have looked at every single word, at every number that was in this report.”

In arriving at its conclusions, the group combed through 9,200 scientific publications, two-thirds of which were published after 2007, and considered the input from nearly 55,000 comments drawn from 1,089 reviewers from 52 countries. A majority of the scientists involved in the latest report were new to the IPCC process.

The report solidifies many of the findings from past IPCC assessments and will help inform policymakers as they try to craft a new global climate treaty in 2015, to enter into force in 2020.

However, many experts within and outside the IPCC think the organization should focus more on short-term, highly focused assessments, rather than the arduous, massive reports that the organization has traditionally produced, and for which it won the Nobel Peace Prize in 2007.

IPCC chairman Rajendra Pachauri said the policy impacts of the report will depend in part on how well the organization publicizes its findings. “The IPCC has to do a lot more in terms of outreach and we’re attempting to do that," he said.

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Comments

By dan_in_illinois
on September 27th, 2013

In light of all the information indicating a “hiatus” in global warming for the last 15 or so years, it seems ridiculous for this group to “double down” on their bets about their climate predictions.

Reply to this comment

By Tregonsee (Nolensville/TN/37067)
on September 27th, 2013

The last shreds of IPCC credibility have vanished with this report.

Reply to this comment

By Kevin
on September 27th, 2013

dan_in_illinois,

What information is that?  Oh, you mean the cherry picked data produced by individuals who receive funding from fossil fuel interests?  Yeah, that’s what I thought…

Kevin

Reply to this comment

By joules beef (columbia)
on September 27th, 2013

There is no hiatus of global warming.  Surface temps have remained at record levels without increasing for the past 15 years, this is due to natural variations overcoming warming influences, just like natural variations combined to give us the 1998 record..the surface temps havent risen in 15 years this is true but there is no haitus of global warming.

WHat you are doing is confusing the center line prediction for specific yearly predictions and that isnt how it works.

an easy way to see that, is the model of flipping a quarter, says I will get 50 percent heads, and 50% tails.. flipping headed 10 times in a row, doesnt mean the model is wrong or that the coin is two headed or misweighted. Because that idea that you can get ten heads in a row, still fits in the model of flipping coins.

What gets me is the same people who said we didnt have enough data to say the earth is warming with an instrumental record of 160 years, now say global warming is bunk based on 15 years of data.

There really isnt any concern in the community over the hiatus, it fits fine in theory and happened in the 50s and 70s, the only people who make a big deal about it are people who dont understand the science,

Reply to this comment

By Sam (Columbia, SC)
on September 27th, 2013

IPCC has ZERO credibility

Reply to this comment

By dan_in_illinois
on September 28th, 2013

Kevin,

Uh, no.  No cherry picked data.  I got the information right here from Climate Central:

http://www.climatecentral.org/news/new-study-ties-global-warming-hiatus-to-a-pacific-cooldown-16405
http://www.climatecentral.org/blogs/ipcc-roundup-early-reports-focus-on-warming-hiatus-16515
http://www.climatecentral.org/news/zeroing-in-on-ipccs-sea-level-rise-warming-hiatus-16532

Reply to this comment

By Jan Freed (l.a./CA/90041)
on October 19th, 2013

The so-called hiatus refers to a slowing of air temperature increases, not a total plateau.

Analogy:  Your child’s temperature increases from 98.6 to 103 degrees F in one week.  The next week it increases to (only)104 degrees F.  A hiatus?

I cannot imagine that anyone who actually cares about the planet (or the child) being reassured.

With CO2 levels constantly above historic normals, this green house gas continues to accumulate additional heat (equal to 4 Hiroshima atomic bombs/sec).  Why would it stop doing that?

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