The last deglaciation was characterized by increases in surface temperatures of 10-15 °C punctuated by millennial-scale warming/cooling periods, pulses of increasing atmospheric carbon dioxide and asynchronously increasing methane. A geospatial-temporal variance analysis reveals a global warming trend correlating with rising CO2 on which is superimposed second trend millennial-scale regional warming/cooling periods associated with variation in the strength of the Atlantic overturning current.
There is strong evidence of marked changes in temperature extremes across the contiguous United States – extreme cold waves have become less common while extreme heat waves have become more common and heavy precipitation events in most parts of the United States have increased in both intensity and frequency. That is the conclusion of a report prepared by scientists from NOAA, NASA and other agencies.
Air bubbles in Greenland ice cores are analyzed to compare changes in Greenland surface temperature and atmospheric methane concentration during a rapid warming event lasting 200 years during the last deglaciation. It is found that changes in Greenland surface temperature and atmospheric methane emissions occurred essentially synchronously indicating that this warming event included the tropics.
During the first pulse of increasing atmospheric CO2 at the beginning of the last deglaciation the carbon-13 ratio dropped precipitously indicating that a source of the CO2 was a large pool of carbon of organic origin. Comparison with other data including the atmospheric carbon-14 record point at outgassing from Southern Ocean deep water as the source of the CO2 increase in this early period of the deglaciation.