Text Size

Earth's 'Tipping Points': How Close Are We? - Presenter Bios
Abrupt changes in climate are now an established phenomenon in Earth's history, and there is growing concern that our planet may be at a "tipping point" of dramatic climate change, this time due to human factors. Scientists from across different disciplines are now looking at many parts of the Earth system for signs of such pivotal shifts either already underway or likely to happen in this century.

This briefing will present the latest results from the perspective of global climate as well as potential impacts on three key regions of the globe. James Hansen discusses the "unrealized" global warming of Earth's climate system and the resulting need for urgent action to cut emissions beyond carbon dioxide. Richard Alley discusses the possibility that sustained warming of a few decades could produce major ice sheet losses that would last centuries. Peter Webster reports on a societal tipping point along three heavily populated Asian river basins when climate-induced changes to river flows collide with population growth. Joey Comiso reports that this year's large Arctic sea ice decline may be the tipping point for perennial ice and a recovery may no longer possible in the foreseeable future.

Reporters will learn about these climatic concerns from several scientists.

Photo of James Hansen James Hansen - director, NASA's Goddard Institute for Space Studies; adjunct professor of geology, Columbia University's Earth Institute

James Hansen heads the NASA Institute for Space Studies in New York City, which is a division of Goddard Space Flight Center's (Greenbelt, Md.), Sciences and Exploration Directorate. He is also an adjunct professor of Geology at Columbia University’s Earth Institute. He was trained in physics and astronomy in the space science program of James Van Allen at the University of Iowa. His early research on the properties of clouds of Venus led to their identification as sulfuric acid. Since the late 1970s, he has worked on studies and computer simulations of Earth's climate for the purpose of understanding the human impact on global climate.

Hansen is best known for his testimony on climate change to congressional committees in the 1980s that helped raise broad awareness of the global warming issue. He was elected to the National Academy of Sciences in 1995 and, in 2001, received both the Heinz Award for environment and the American Geophysical Union's Roger Revelle Medal. In 2006, Hansen received the World Wildlife Federation’s Conservation Medal from the Duke of Edinburgh and was designated by Time Magazine as one of the 100 most influential people in 2006. Hansen is also a 2007 Laureate of the Dan David Prize for the field of Quest for Energy.

Photo of Richard Alley Richard Alley - Evan Pugh professor of geosciences and associate of the Earth and Environmental Systems Institute, Pennsylvania State University

Richard Alley is the Evan Pugh professor of geosciences and associate of the Earth and Environmental Systems Institute at The Pennsylvania State University, University Park, where he has worked since 1988. Alley teaches and conducts research on the climatic records, flow behavior and sedimentary deposits of large ice sheets, to aid in prediction of future changes in climate and sea level. His experience includes three field seasons in Antarctica, eight in Greenland and three in Alaska.

Alley has served on a variety of advisory panels and steering committees, including chairing the National Research Council’s Panel on Abrupt Climate Change and participating in the UN Intergovernmental Panel on Climate Change (and thus sharing in the 2007 Nobel Peace Prize). He has provided requested advice to numerous government officials in multiple administrations, including a U.S. vice president, the president's science adviser, and committees and individual members of the Senate and the House of Representatives. Alley will be presented with the Roger Revelle Medal of the American Geophysical Union in December.

Photo of Josefino Comiso Josefino Comiso - senior research scientist for polar oceanography, NASA's Goddard Space Flight Center

Josefino Comiso is a senior research scientist at the Cryospheric Sciences Branch of NASA's Goddard Space Flight Center. His research interests include climate change, polar oceanography and sea ice, as observed by satellite sensors, with emphasis on the rapid decline of the Arctic perennial ice cover. He developed sea ice and surface ice temperature algorithms and was the chief scientist in many NASA aircraft missions, including a flight over a nuclear submarine in the Arctic. He co-authored satellite atlases on sea ice that revealed for the first time the true extent and spatial distribution of sea ice in the polar regions. He has been the recipient of several NASA performance and group awards and in 2006, was a fellow of the Japanese Society for the Promotion of Science and a guest professor at Chiba University in Japan.

Photo of Peter Webster Peter Webster - professor in the School of Earth and Atmospheric Sciences, Georgia Institute of Technology

Peter Webster is a professor of earth and atmospheric sciences and environmental engineering at the Georgia Institute of Technology. For the last 30 years he has concentrated on the investigation of climate issues with emphases on tropical atmospheres and oceans, the monsoons of Asia and ocean-atmosphere interaction. Most of Webster's research combines theoretical and modeling techniques, although he has organized many field experiments, including TOGA Coupled Ocean-Atmosphere Response Experiment (a multinational experiment in the western Pacific Ocean), the Equatorial Mesoscale Experiment (in North Australia) and the Joint Air-Sea Monsoon Interaction Experiment in the Bay of Bengal.

In recent years he has directed the Climate Forecast Applications in Bangladesh, a program aimed at introducing modern predictive techniques to developing countries and producing forecasts of rainfall and floods on seasonal and daily timescales. The forecast techniques have provided Bangladesh with the most advanced modeling scheme in the world resulting in 10-day warning of the two major Brahmaputra floods during the monsoon season of 2007.

Most recently, Webster has worked on the roles that hurricanes and tropical storms play in the heat balance of the planet and how their characteristics may be changing in a warming world. In addition, he has become interested in the changing state of the tropical ocean warm pool and river discharge that has occurred during the most recent 100 years and that which may occur in the next 100 years.

> Back to the 'Tipping Points' summary page