Sensitive climate
Nature Geoscience
December 7, 2009

Three to five million years ago, global temperatures were significantly higher than expected from atmospheric carbon dioxide levels at the time, according to a study published online this week in Nature Geoscience. The authors conclude that the higher long-term sensitivity of the Earth system should be taken into account when defining dangerous anthropogenic climate change.
Daniel Lunt and colleagues combine a global climate model with a reconstruction of the Earth’s environment three to five million years ago, when temperatures were 3 to 5℃ warmer than today. They use the model to separate various contributions to global temperatures, and find that atmospheric carbon dioxide concentrations caused more warming than would be expected from the estimates of climate sensitivity that are used for future climate projections. They conclude that the discrepancy arises because in the earlier period the Earth system had a long time to adjust to the environmental conditions, whereas climate models for future projections do not fully include feedbacks that involve slowly changing parts of the system, such as ice sheets or vegetation patterns.
doi: 10.1038/ngeo706
Research highlights
-
Jan 15
Environment: Seagrass meadows may facilitate marine plastic removal from the seaScientific Reports
-
Jan 15
Planetary Science: Mercury may have shrunk less than previously thoughtCommunications Earth&Environment
-
Jan 13
Environment: Polyester fibres found to be widespread in the ArcticNature Communications
-
Dec 23
Planetary science: Over 100,000 new craters identified on the MoonNature Communications
-
Dec 22
Conservation: Agricultural expansion could cause widespread biodiversity declines by 2050Nature Sustainability
-
Dec 18
Geology: Alpine summits may have been ice-free during life of Tyrolean IcemanScientific Reports