A new research determined that we might be able to greatly delay the start of the next ice age, by controlling emissions of fossil fuels.
From an Earth history perspective, we are living in cold times. The greatest climate challenge mankind has faced has been surviving ice ages that have dominated climate during the past million years.
Therefore, it is not surprising that back in the relatively cold 1970's, prominent scientists like Soviet Union climatologist Mikhail Budyko, greeted man-made global warming from CO2 emissions as a way to keep us out of future ice ages.
Similar thoughts are still shared by many scientists who feel that continued high fossil fuel emissions are good for this reason.
In the new research, professor Gary Shaffer of the Niels Bohr Institute, University of Copenhagen, and also leader of the research team at the Danish Center for Earth System Science (DCESS), outlines a way to keep the Earth out of both Hot and Icehouses for a half a million years into the future.
Ice ages start when conditions at high northern latitudes allow winter snowfall to persist over the summer for enough years to accumulate and build ice sheets.
Such conditions depend mainly on summer solar radiation there and atmospheric CO2 concentration.
This radiation is modulated on time scales of 20.000, 40.000 and 100.000 years by changes in the Earth's orbit and orientation.
Critical summer solar radiation for initiating ice sheet growth can be significantly lower for higher atmospheric CO2 with its greenhouse warming effect.
Professor Shaffer made long projections over the next 500,000 years with the DCESS Earth System Model to calculate the evolution of atmospheric CO2 for different fossil fuel emission strategies.
He also used results of a coupled climate-ice sheet model for the dependency on atmospheric CO2 of critical summer solar radiation at high northern latitudes for an ice age onset.
The results show global warming of almost 5 degrees Celsius above present for a "business as usual" scenario whereby all 5000 billion tons of fossil fuel carbon in accessible reserves are burned within the next few centuries.
According to Professor Shaffer, humanity has already increased atmospheric CO2 enough to keep it out of the next ice age for at least the next 55,000 years.