Evolution carbon 14 dating global warming
Feng He of the University of Wisconsin, Madison, a postdoctoral researcher, plugged the main forcings driving global climate over this time interval into an Intergovernmental Panel on Climate Change (IPCC)–class model called the Community Climate System Model version 3, a global climate model that couples interactions between atmosphere, oceans, lands, and sea ice.
The climate science community developed the model with support from the National Science Foundation (NSF), Department of Energy (DOE), and National Aeronautics and Space Administration and used many codes developed by university researchers.
This rise in carbon dioxide then initiated worldwide warming.
The seesawing of heat between the hemispheres due to the AMOC shutdown explains why Southern Hemisphere warming led the rise in carbon dioxide while Northern Hemisphere temperatures lagged behind and reconciles these patterns with the key role played by carbon dioxide in driving global mean warming.
The paleoclimate community generated the proxy data sets and provided unpublished results of the DATED Project on retreat history of the Eurasian ice sheets.
The NOAA NGDC and PANGAEA databases were also essential to this work.
“We found that global temperature mirrored and generally lagged behind rising carbon dioxide during the last deglaciation, which points to carbon dioxide as the major driver of global warming.” Prior results based on Antarctic ice cores had indicated that local temperatures in Antarctica started warming before carbon dioxide began rising, which implied that carbon dioxide was a feedback to some other leading driver of warming.
The delay of global temperature behind carbon dioxide found in this study, however, shows that the ice-core perspective does not apply to the globe as a whole and instead suggests that carbon dioxide was the primary driver of worldwide warming.
Called the Atlantic meridional overturning circulation (AMOC), this ocean conveyor belt is particularly important in the Atlantic where it flows northward across the equator, stealing Southern Hemisphere heat and exporting it to the Northern Hemisphere.
As the dominant theory goes, the variation of Earth’s orbit around the sun is responsible for the growth and deterioration of glaciers because it changes insolation, or solar radiation reaching and warming an area.
About 21,000 years ago the orbit of the Earth was slightly predisposed to warmer summers in the Northern Hemisphere, and the planet experienced a general warming. Geologic data show that about 19,000 years ago, Northern Hemisphere glaciers began to melt, and sea levels rose.
A multi-institutional team led by researchers at Harvard, Oregon State University, and the University of Wisconsin used a global dataset of paleoclimate records and the Jaguar supercomputer at Oak Ridge National Laboratory (ORNL) to find the answer (spoiler alert: carbon dioxide drives warming).
The results, published in the April 5 issue of analyze 15,000 years of climate history.
NSF supported this research through its Paleoclimate Program for the Paleovar Project and NCAR.