Past, present and future levels of greenhouse gases in the atmosphere and model projections of related climatic changes

• Published in: Journal of Experimental Botany
• Main Author: Roeckner, E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1992
• Subjects: ice core
• Online Access: http://hdl.handle.net/21.11116/0000-000C-3B62-4; http://hdl.handle.net/21.11116/0000-000C-3B64-2

Ice core analyses of polar ice reveal a high correlation between climatic change and variations in the atmospheric concentrations of greenhouse gases (carbon dioxide and methane) over the last 160 000 years. Although the resolution of the data is not sufficient to determine the phase relationship between the respective variations, it is generally believed that climate change occurred first as a result of the quasi-periodic variations of the Earth's orbital parameters. However, data and model results are consistent with the hypothesis that climate and atmospheric concentrations of greenhouse gases interact via a positive feedback loop. The more recent increase in greenhouse gases since pre-industrial times can be related to human activities. Climate models predict a significant global warming of several degrees within the next century if the industrial emissions increase unabated. On the other hand, accelerated policies on emission control will significantly reduce the warming after a response time of a few decades.