Abrupt climate change reveals future risks
The main aim of the INTERCLIMA (Inter-hemispheric coupling of abrupt climate change project) was to increase understanding of the underlying mechanisms and inter-hemispheric coupling involved in abrupt climate change. Abrupt climate change involves complex interactions between all components in the climate system. In the past, such changes have occurred as a result of natural factors. However, in the future they may be due to human activities. INTERCLIMA, therefore, investigated past abrupt changes to better understand what threats may lie in wait. Project partners compared the Law Dome ice core record from Antarctica with ice cores from Greenland in the Arctic to estimate inter-polar phasing of abrupt climate change during the last interglacial. Results showed that changes in climate trends in Antarctic lag behind abrupt climate change in Greenland by 200 years. An additional 84 paleoclimate records based on ice, marine and terrestrial data from the less studied Southern Hemisphere were used to obtain a broader view of the regional extent of abrupt climate change. This information was used to assess general circulation model experiments. They revealed that large-scale changes in meridional heat transport by the ocean and the atmosphere were needed in order to explain past abrupt climate change events. Proxy climate data was used to test model simulations that attempted to explain the mechanisms involved in past Antarctic warming events. These involved the release of heat from Southern Ocean deep-convection coupled with albedo feedbacks (where sunlight is reflected by the ice) and increased atmospheric heat transport to Antarctica. Results were published in 3 leading scientific journals. They will enable scientists and policymakers to make well-informed decisions on how best to mitigate the worst effects of climate change by revealing what the climate system is capable of. INTERCLIMA has increased understanding of how abrupt climate change signals are communicated to different parts of the system. It demonstrated that changes in meridional atmospheric heat transport drive variability in the southern hemisphere tropics. The project also showed that slower ocean heat transport changes and sea ice feedbacks are more important in communicating abrupt climate change signals to the southern high latitudes.
Keywords
INTERCLIMA, abrupt climate change, inter-hemispheric coupling, Law Dome, general circulation model
