PROJECTS

As one of its series of 21 synthesis and assessment reports, the U.S. Climate Change Science Program published a report in June 2008 on Weather and Climate Extremes in a Changing Climate. The report focused on North America, with the team including scientists from the U.S., Canada, and Mexico. Susan served as Senior Editor of this report, focusing her attention on the Synopsis and Executive Summary, which are written to be accessible to non-scientists. The remainder of the report is much more technical. The key findings of this report are summarized in the report's Synopsis, reproduced below.

Changes in extreme weather and climate events have significant impacts and are among the most serious challenges to society in coping with a changing climate. Many extremes and their associated impacts are now changing. For example, in recent decades most of North America has been experiencing more unusually hot days and nights, fewer unusually cold days and nights, and fewer frost days. Heavy downpours have become more frequent and intense. Droughts are becoming more severe in some regions, though there are no clear trends for North America as a whole. The power and frequency of Atlantic hurricanes have increased substantially in recent decades, though North American mainland land-falling hurricanes do not appear to have increased over the past century. Outside the tropics, storm tracks are shifting northward and the strongest storms are becoming even stronger.

It is well established through formal attribution studies that the global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases. Such studies have only recently been used to determine the causes of some changes in extremes at the scale of a continent. Certain aspects of observed increases in temperature extremes have been linked to human influences. The increase in heavy precipitation events is associated with an increase in water vapor, and the latter has been attributed to human-induced warming. No formal attribution studies for changes in drought severity in North America have been attempted. There is evidence suggesting a human contribution to recent changes in hurricane activity as well as in storms outside the tropics, though a confident assessment will require further study.

In the future, with continued global warming, heat waves and heavy downpours are very likely to further increase in frequency and intensity. Substantial areas of North America are likely to have more frequent droughts of greater severity. Hurricane wind speeds, rainfall intensity, and storm surge levels are likely to increase. The strongest cold season storms are likely to become more frequent, with stronger winds and more extreme wave heights.

Current and future impacts resulting from these changes depend not only on the changes
in extremes, but also on responses by human and natural systems.

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As the first in its series of synthesis and assessment products, the U.S. Climate Change Science Program published a report in April 2006 on Temperature Trends in the Lower Atmosphere. Susan Joy Hassol served as Associate Editor of this report. The Abstract (Synopsis) and Executive Summary are written to be accessible to non-scientists. The remainder of the report is more technical. The key findings of this report are summarized in the report's Abstract, reproduced below.

Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human-induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies.

This Synthesis and Assessment Product is an important revision to the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change. For recent decades, all current atmospheric data sets now show global-average warming that is similar to the surface warming. While these data are consistent with the results from climate models at the global scale, discrepancies in the tropics remain to be resolved. Nevertheless, the most recent observational and model evidence has increased confidence in our understanding of observed climate changes and their causes.

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The Presidential Climate Action Project is a non-partisan effort to develop a comprehensive menu of policy options, rooted in science, for the next president to begin implementing immediately upon taking office. At the request of the Project, Susan prepared these responses to key questions about how to determine the emissions reductions that will be needed to stabilize climate.

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In a departure from her usual work in the scientific community, this project marked a foray into the world of television for Susan. As the writer of Too Hot Not To Handle, HBO's one-hour global warming documentary, Susan helped select the stories and scientists that would best convey the impacts of climate change on the lives of Americans and communicate the variety of solutions already underway to address the climate challenge. Susan traveled to Alaska with an HBO crew to film on location on melting glaciers, in burned forests, and in a village succumbing to coastal erosion. The show garnered over four million viewers on the night it premiered in April 2006 and many more since. It is available on DVD from HBO and other online distributors.

With her colleague Robert Corell, Susan contributed a chapter that summarized the key findings of the Arctic Climate Impact Assessment to the peer-reviewed book Avoiding Dangerous Climate Change, published by Cambridge University Press in 2006.  This volume grew out of a symposium that took place at the UK Met Office in Exeter in 2005 at the invitation of Prime Minister Tony Blair. The book covers a wide range of topics vital to understanding the climate challenge, from the operation of the global climate system, to its key vulnerabilities and thresholds, to an assessment of the technologies that will be required to rein in climate disruption.

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This article by Susan Joy Hassol and Randy Udall was published in 2003 in Issues and Science and Technology, a journal of the National Academy of Sciences. It highlights state, local and corporate action on climate change in the absence of federal leadership.

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With colleagues Neil Strachan and Hadi Dowlatabadi, Susan co-authored the chapter on energy efficiency in this book, edited by Robert Watts and published in 2002 by Cambridge University Press. The chapter explains that improved energy efficiency is an essential part of the solution to reducing greenhouse gas emissions and meeting global energy demand while also improving economic performance, increasing jobs, and enhancing environmental quality. It also describes the polices needed to promote efficiency, including a realistic price of energy that internalizes all the costs associated with its use, increased investment in research, development and deployment of key technologies, and energy efficiency standards.

Susan was one of the lead authors of this first U.S. national assessment of climate change and its impacts. The study concluded that humanity's influence on the global climate would grow in the coming century, presenting increasing challenges for the United States that would vary by region and sector.

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Working with the Scientific Committee on Problems of the Environment, Susan co-authored the Emerging Challenges section of the UNEP GEO Yearbook for 2003, which addressed the alteration of the nitrogen cycle and over-fishing. In 2008, Susan was one of three lead authors, along with Jerry Melillo, Bob Corell, and a team of top experts from around the world, who produced the GEO Yearbook chapter on Methane from the Arctic: Global Warming Wildcard.

Download "Methane from the Arctic: Global Warming Wildcard" (6.9 mb PDF)