Thure Cerling is a pioneer in the use of stable isotopes of Carbon, Nitrogen and Oxygen to study historic changes in CO2 levels in the Earth’s atmosphere. He was elected to the National Academy of Sciences in 2001. In recent years he’s used stable isotopes to analyze hair, teeth and bone to better understand the impacts of changing CO2 levels on habitat, animals and man.
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Models do ‘okay’ at predicting changes in surface mass balance of Greenland’s ice sheets, says Fiamma Straneo. They don’t do so well, and therefore are not very useful, when it comes to predicting the accelerated melting that is now occurring and which, she says, now accounts for about one-fourth of global sea level rise. In this presentation she reviews her studies of what is happening in that dynamic space at the edge of the ice sheets where atmosphere, ocean and glacier all come together, and the various mechanisms proposed as contributing to ice sheet loss.
Sedimentation rates in parts of the Arctic Ocean are surprisingly high with 1-2% of that sediment originating from ‘dirty ice,’ says Professor Emeritus Dennis Darby. He explains various processes that govern the formation of sea ice and how sediment can be entrained in it, the processes and routes by which ‘dirty ice’ is transported throughout the Arctic, and his data base of 38,000 different samples permits tracking sediment collected from the sea floor back to its point of origin.
The workshop’s first presentation was a status report on arctic climate from Dr. Jennifer Francis. In the past 30 years, she says, aerial coverage of sea ice has been reduced by half. Ice volume had declined 70% over the same period. She offers a novel hypothesis that Arctic amplification “regional warming in excess of the global average” causes the jet stream to slacken producing meanders that ‘lock in’ and cause aberrant weather for prolonged periods of time. Satellite imagery and this past winter’s ‘polar vortex’ and extended drought in the W.
YCEI’s 5th Annual Conference honored founding director IPCC Chairman Dr. Rajendra Pachauri. Dr. Pachauri reviewed his tenure at the helm of the YCEI in a presentation that concluded the conference. Yale President Peter Salovey made a surprise appearance, thanking Dr.
Yale Professor Ron Smith speaks on Climate Change in New England at a A Town Hall Meeting, entitled, “Climate Change in New England: What’s Next?” which explores how global warming will affect New England in the 21st century and how the region is preparing for the coming changes.
Assistant Professor Trude Storelvmo presents research which suggests that the cooling effect of aerosols may mask up to 0.5 degrees of warming. The implications are significant, as efforts to abate air pollution that health officials attribute to millions of deaths each year around the global will exacerbate warming trends and suggest that equilibrium climate sensitivity is at the higher end of ranges reported in the most recent IPCC Assessment Report.
Kevin Trenbeth, from the National Center for Atmospheric Research (NCAR), addresses a recent and recurring question about a conjectured pause in the rise of global surface temperatures during YCEI’s workshop on “Uncertainty in Climate Change: A Conversation with Climate Scientists and Economists”
Klaus Keller is an associate professor in the Department of Geosciences at Penn State University and an adjunct professor in the Department of Engineering and Public Policy at Carnegie Mellon University.
Fran Ulmer reminds people that “Antarctica has penguins. The Arctic has people.” Ms. Ulmer was a University of Alaska Chancellor and Lieutenant Governor of Alaska from 1994-2002. She talks about the effects of climate change in Alaska where average seasonal temperatures have already increased by 4 degrees in summer and 7 degrees in winter. Her talk is wonderful for anyone who forgets how very different the situation is at the Earth’s poles: Antarctica is uninhabited land surrounded by an ocean, whereas the Arctic is an ocean surrounded by 8 nations.
William Nordhaus is the Sterling Professor of Economics at Yale University and author of over 20 books, including the recently published “The Climate Casino: Risk, Uncertainty, and Economics for a Warming World.” His DICE model is one of the first and still most widely utilized integrated assessment models for considering the relationships between climate change, energy consumption and economic impacts. What is really relevant to the discussion of uncertainty, says Professor Nordhaus, is an understanding of statistics, which is the subject of his talk.
Chris Forest, Pennsylvania State University, discusses estimations of climate sensitivity and testing of models against what is known about the past thousand years.
Stephen Schwarz, Brookhaven National Laboratory, delivers a talk entitled, “Empirical Determination of Earth’s Climate Sensitivity and Implications of Present Uncertainties”, at the YCEI conference “Uncertainty in Climate Change: A Conversation with Climate Scientists and Economists”.
Martin Weitzman of Harvard University begins his discussion by reviewing the most recent IPCC Summary Report and the language they use for describing the likelihood of various climate sensitivity scenarios. He relates that language and those likelihoods to the various probability distributions calculated by climate and economic modelers.
Gary Yohe of Wesleyan University explains how the value of information regarding projections of climate sensitivity depends on:
1. what the decisions are to be made about and for whom, 2. the character of the decision space (states of nature, irreversibility, persistence, etc.), 3. decisions based on the range of “states of nature” and “their distributions”, 4. decision makers prior assumptions about those distributions, 5. decision makers’ attitudes (averstion) towards risk, 6. timing of the decision.
Yale Professor Ken Gillingham welcomes participants in this YCEI sponsored workshop that brings together climate change scientists and economists whose modeling efforts hinge on the need to accommodate anticipated climate change in a warming world.
He sets the stage for the day’s conversations by reviewing the just released IPCC 5th Assessment Report, some of its findings, and the unique language that the IPCC uses to describe uncertainty in climate sensitivity, the key parameter that concerns economists and climate scientists.
Dan Lunt, from the University of Bristol’s School of Geographical Sciences in the United Kingdom, discusses the basics of climate modeling and a history of how models have grown in sophistication and the questions that remain today. Dr. Lunt describes his research interests as broad, with a special focus on icesheet-climate interactions and comparison of the paleo record with climate models.
Clark University’s Christopher Williams trained as a land surface hydrologist and terrestrial ecosystem ecologist. Clark University’s website reports on his work:
“Chris investigates how earth’s biosphere responds to natural and human perturbations such as severe drought events, bark beetle outbreaks, fires, harvesting, and land cover changes.”
Mary Louise Timmermans introduces Peter Rhines who shares his latest field observations from the subpolar Atlantic and what they offer climate modelers. Peter’s talk covers introductory concepts related to Arctic climate and how it influences atmospheric and oceanic circulation as well as more technical information on ocean circulation dynamics which exert tong controls yet are under-represented in IPCC-class coupled climate models.