Simulation of long-term future climate changes with the green McGill paleoclimate model: the next glacial inception

• Published in: Climatic change 2006-12, Vol.79 (3-4), p.381-401
• Main Authors: Cochelin, Anne-Sophie B, Mysak, Lawrence A, Wang, Zhaomin
• Format: Article
• Language: English
• Subjects: Atmosphere; Atmospheric models; Carbon dioxide; Climate change; Climatology. Bioclimatology. Climate change; Computer simulation; Earth, ocean, space; Exact sciences and technology; External geophysics; Flowers & plants; General circulation models; Glaciers; Global warming; Greenhouse gases; Ice ages; Ice sheets; Meteorology; Paleoclimate; Vegetation
• ISSN: 0165-0009; 1573-1480
• DOI: 10.1007/s10584-006-9099-1

The multi-component “green” McGill Paleoclimate Model (MPM), which includes interactive vegetation, is used to simulate the next glacial inception under orbital and prescribed atmospheric CO₂ forcing. This intermediate complexity model is first run for short-term periods with an increasing atmospheric CO₂ concentration; the model's response is in general agreement with the results of GCMs for CO₂ doubling. The green MPM is then used to derive projections of the climate for the next 100 kyr. Under a constant CO₂ level, the model produces three types of evolution for the ice volume: an imminent glacial inception (low CO₂ levels), a glacial inception in 50 kyr (CO₂ levels of 280 or 290 ppm), or no glacial inception during the next 100 kyr (CO₂ levels of 300 ppm and higher). This high sensitivity to the CO₂ level is due to the exceptionally weak future variations of the summer insolation at high northern latitudes. The changes in vegetation re-inforce the buildup of ice sheets after glacial inception. Finally, if an initial global warming episode of finite duration is included, after which the atmospheric CO₂ level is assumed to stabilize at 280, 290 or 300 ppm, the impact of this warming is seen only in the first 5 kyr of the run; after this time the response is insensitive to the early warming perturbation.