Wednesday, May 15, 2013
Environmental Science and Engineering Seminar
The Global Warming Yardstick: What Warming Oceans and Rising Seas Tell Us about Anthropogenic Climate Change
Josh Willis, Project Scientist - Jason-3, Climate, Oceans and Solid Earth Sciences, Jet Propulsion Laboratory
As the oceans warm due to human-caused climate change, they contribute to both global and regional sea level rise. But the total amount of heat absorbed by the ocean also reflects the net forcing applied to the Earth's climate system. In this way, the oceans provide a critical measure of human-kind's influence on global climate. Several global observing systems now make it possible to assess the components of sea level rise and the net radiative forcing independently. Argo provides information about ocean warming, GRACE provides information about addition of water to the oceans, the CERES satellites measure changes in the net radiative imbalance at the top of the atmosphere and satellite altimeters observe global sea level change with an accuracy of a few millimeters. Several recent results that hinge on these observations will be reviewed. For the past decade or so, the global sea level and energy budgets are well understood. Between 2010 and 2012, global sea levels experienced large interannual variations, of 5 to 7 mm that were due primarily to the exchange of water between the oceans and the continents. In addition, a recent reanalysis of data from the HMS Challenger Expedition of 1872-76 has interesting implications for net radiative forcing over the last 130 years.