This work out of the Department of Global Ecology, Carnegie Institution for Science, reduces the lag in warming from CO2 emissions from 30 to 50 years to 10. But their constraints are quite different from what we have come to know as the temperature lag.
This experiment looked at 6,000 model runs of a 100 gigaton (Gt) pulse of CO2 emitted all at once into a climate system in equilibrium. What they found was that the global temperature rise took ten years to peak, then slowly fell for what appears to be multiple millennia. The findings only revealed the first hundred years and disconcertingly, the temperature only fell about 5 percent from peak warming after 100 years.
This experiment is significantly different than our ongoing earth experiment that we are all unwittingly playing a part. Earth’s climate is nowhere close to equilibrium to start with. We also emit about 40 Gt of CO2 every year, vs. the 100 Gt pulse used in this research.
Still, this work is useful. It appears quite likely that the lag is a bit shorter than previously understood.
Ricke and Caldiera conclude: “The primary time lag limiting efforts to diminish future
climate change may be the time scales associated with political
consensus and with energy system transitions, and not time lags in the physical climate
system. While the relevant time lags imposed by the climate
system are substantially shorter than a human lifetime, they
are substantially longer than the typical political election
cycle, making these delays and their associated uncertainties
important, both economically and politically. Nonetheless,
our study indicates that people alive today are very likely to
benefit from emissions avoided today.”
Ricke and Caldiera, Maximum warming occurs about one decade after a carbon dioxide emission, IOPScience, December 2, 2014.