The world's average temperature will increase by about eight degrees Celsius by 2300 if the planet's remaining fossil fuel resources are burned, which is equivalent to five trillion tons (five EgC) of CO2 emissions, according to a report published Monday in the journal Nature Climate Change.
A team from Canada used a set of comprehensive, complex Earth system models to simulate long-term warming in response to five EgC. Researchers only calculated the effect of burning all fossil fuels currently known, not including future finds or those made available by new extraction technologies.
The result suggests that, in the absence of mitigation, warming is likely to be considerably larger than previously anticipated.
When the effect of other greenhouse gases is added, the global temperature increase will climb to approximately 10 degrees Celsius.
The rise of temperature predicted by the models varies around the globe. In the Arctic, the higher CO2 levels will lead to 17 degrees Celsius of warming, with another three degrees Celsius from other greenhouse gases, by 2300.
In comparison, Earth system models that are not as comprehensive or complex show that there will be less warming, possibly due to the incorrect representation of certain processes and feedbacks, such as the efficiency of ocean heat uptake, according to the study.
The new study also suggest that five EgC will increase the average regional precipitation by more than a factor of four in the tropical Pacific, but lower it by more than a factor of two over parts of Australia, the Mediterranean, southern Africa and the Amazon, and by a factor of three in central America and North Africa.
This study "implies that the unregulated exploitation of fossil fuel resources could result in significant, more profound climate change," said Thomas Frolicher, at ETH Zurich in Switzerland, in an accompanying article.
