AGU Revised Statement on Climate Change: "Human induced climate change requires urgent action:

from Eli Rabett, Rabett Run, August 5, 2013

The AGU has issued its revised statement on climate change, approved by the fifteen member committee chaired by Gerald North with one (predictable) dissent. 

Human induced climate change requires urgent action.

Humanity is the major influence on the global climate change observed over the past 50 years.

Rapid societal responses can significantly lessen negative outcomes.

Human activities are changing Earth’s climate. At the global level, atmospheric concentrations of carbon dioxide and other heat trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase.  Human caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8 °C (1.5 °F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present, and future emissions will influence the climate
system for millennia. 

Extensive, independent observations confirm the reality of global warming. These observations show large scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. These changes are broadly consistent with long understood physics and predictions of how the climate system is expected to respond to human caused increases in greenhouse gases. The changes are inconsistent with explanations of climate change that rely on known natural influences.

Climate models predict that global temperatures will continue to rise, with the amount of warming primarily determined by the level of emissions. Higher emissions of greenhouse gases will lead to larger warming, and greater risks to society and ecosystems. Some additional warming is unavoidable due to past emissions.

Climate change is not expected to be uniform over space or time. Deforestation, urbanization, and particulate pollution can have complex geographical, seasonal, and longer term effects on temperature, precipitation, and cloud properties. In addition, human induced climate change may alter atmospheric circulation, dislocating historical patterns of natural variability and storminess.

In the current climate, weather experienced at a given location or region varies from year to year; in a changing climate, both the nature of that variability and the basic patterns of weather experienced can change, sometimes in counterintuitive ways -- some areas may experience cooling, for instance. This raises no challenge to the reality of human induced climate change.

Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels.

While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.

Actions that could diminish the threats posed by climate change to society and ecosystems include substantial emissions cuts to reduce the magnitude of climate change, as well as preparing for changes that are now unavoidable. The community of scientists has responsibilities to improve overall understanding of climate change and its impacts. Improvements will come from pursuing the research needed to understand climate change, working with stakeholders to identify relevant information, and conveying understanding clearly and accurately, both to decision makers and to the general public.

Adopted by the American Geophysical Union
December 2003; Revised and Reaffirmed December 2007, February 2012, August 2013.

The 15-person panel that reviewed and updated the position statement included the following:

• Amy Clement, Rosenstiel School of Marine and Atmospheric Science, University of Miami (approve)
• John Farrington, Woods Hole Oceanographic Institute (approve)
• Susan Joy Hassol, Climate Communication (approve)
• Robert Hirsch, U.S. Geological Survey (approve)
• Peter Huybers, Harvard University (approve)
• Peter Lemke, Alfred Wegener Institute (approve)
• Gerald North, Texas A&M University (approve, panel chair)
• Michael Oppenheimer, Princeton University (approve)
• Roger Pielke Sr., University of Colorado Boulder (dissent)
• Ben Santer, Lawrence Livermore National Laboratory (approve)
• Gavin Schmidt, Goddard Institute for Space Studies, NASA (approve)
• Leonard A. Smith, London School of Economics (approve)
• Eric Sundquist, U.S. Geological Survey (approve)
• Pieter Tans, National Oceanic and Atmospheric Administration (approve)

It is notable here that the committee was quite willing to vote the statement out based on a strong consensus but not unanimity. As Eli noted in December last after attending the Fall AGU meeting, climate scientists are not only 97% for the proposition that the climate is changing driven by human influences but that it is also dangerous.  Action to stop carbon emissions is needed immediately.

The mood of the attendees had shifted.  It was much sourer about the few in the atmospheric science community still running interference for inactivism.  People were being called out in private, but also in public and not just in sessions dealing with education and communication and blogging.

It is now clear to the climate science community that keeping your head down has not been an effective option for climate scientists for quite a while (see Kathryn Hayhoe).  The denialists and their funders are  coming for you in the Niemoeller sense, sooner or later.  This means that many in the community have woken up.  Those who do not, or believe they cannot, are feeling guilty about not supporting the science they are part of.  Those folks need to be encouraged and supported and come out.
http://rabett.blogspot.com/2013/08/revised-agu-statement-on-climate-change.html

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Bombshell: Recent Warming Is ‘Amazing And Atypical’ And Poised To Destroy Stable Climate That Enabled Civilization

by Joe Romm, Climate Progress, March 8, 2013

New Science Study Confirms ‘Hockey Stick’: The Rate Of Warming Since 1900 Is 50 Times Greater Than The Rate Of Cooling In Previous 5,000 Years!

Temperature change over past 11,300 years (in blue, via Science, 2013) plus projected warming this century on humanity’s current emissions path (in red, via recent literature).

A stable climate enabled the development of modern civilization, global agriculture, and a world that could sustain a vast population. Now, the most comprehensive “Reconstruction of Regional and Global Temperature for the Past 11,300 Years” ever done reveals just how stable the climate has been — and just how destabilizing manmade carbon pollution has been and will continue to be unless we dramatically reverse emissions trends.

Researchers at Oregon State University (OSU) and Harvard University published their findings today in the journal Science. Their funder, the National Science Foundation, explains in a news release:

With data from 73 ice and sediment core monitoring sites around the world, scientists have reconstructed Earth’s temperature history back to the end of the last Ice Age.

The analysis reveals that the planet today is warmer than it’s been during 70 to 80% of the last 11,300 years. 

… during the last 5,000 years, the Earth on average cooled about 1.3 F – until the last 100 years, when it warmed about 1.3 F.

In short, thanks primarily to carbon pollution, the temperature is changing 50 times faster than it did during the time modern civilization and agriculture developed, a time when humans figured out where the climate conditions — and rivers and sea levels — were most suited for living and farming. We are headed for 7 to 11 °F warming this century on our current emissions path — increasing the rate of change 5-fold yet again.

By the second half of this century we will have some 9 billion people, a large fraction of whom will be living in places that simply can’t sustain them — either because it is too hot and/or dry, the land is no longer arable, their glacially fed rivers have dried up, or the seas have risen too much.

We could keep that warming close to 4 °F — and avoid the worst consequences — but only with immediate action.

This research vindicates the work of Michael Mann and others showing that recent warming is unprecedented in magnitude, speed, and cause during the past 2,000 years — the so-called Hockey Stick — and in fact extends that back to at least 4,000 years ago. I should say “vindicates for the umpteenth time” (see “Yet More Studies Back Hockey Stick“).

Lead author Shaun Marcott of OSU told NPR that the paleoclimate data reveal just how unprecedented our current warming is: “It’s really the rates of change here that’s amazing and atypical.” He noted to the AP, “Even in the ice age the global temperature never changed this quickly.”

And the rate of warming is what matters most, as Mann noted in an email to me:

This is an important paper. The key take home conclusion is that the rate and magnitude of recent global warmth appears unprecedented for *at least* the past 4K and the rate *at least* the past 11K. We know that there were periods in the past that were warmer than today, for example the early Cretaceous period 100 million yr ago. The real issue, from a climate change impacts point of view, is the rate of change—because that’s what challenges our adaptive capacity. And this paper suggests that the current rate has no precedent as far back as we can go w/ any confidence—11 kyr arguably, based on this study.

Katharine Hayhoe, an atmospheric scientist at Texas Tech University, told the AP:

We have, through human emissions of carbon dioxide and other heat-trapping gases, indefinitely delayed the onset of the next ice age and are now heading into an unknown future where humans control the thermostat of the planet.

Unfortunately, we have decided to change the setting on the thermostat from “Very Stable, Don’t Adjust” to “Hell and High Water.” It is the single most self-destructive act humanity has ever undertaken, but there is still time to aggressively slash emissions and aim for a setting of “Dangerous, But Probably Not Fatal.”

http://thinkprogress.org/climate/2013/03/08/1691411/bombshell-recent-warming-is-amazing-and-atypical-and-poised-to-destroy-stable-climate-that-made-civilization-possible/

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