If carbon dioxide emission suddenly stopped, the amount of gas already in the Earth's atmosphere could warm the planet for hundreds of years, according to a new study.
According to a Princeton University-led study published in the journal Nature Climate Change, The amount of carbon dioxide present in the Earth's atmosphere could warm the planet for close to 1000 years.
"The regional uptake of heat plays a central role. Previous models have not really represented that very well," Thomas Frölicher, first study author and a researcher at the Swiss Federal Institute of Technology in Zurich, said in a statement. "Scientists have thought that the temperature stays constant or declines once emissions stop, but now we show that the possibility of a temperature increase cannot be excluded. This is illustrative of how difficult it may be to reverse climate change - we stop the emissions, but still get an increase in the global mean temperature."
In the study, researchers simulated the planet Earth on which, after 1,800 billion tons of carbon entered the atmosphere, all carbon dioxide emissions suddenly stopped.
They observed that within a millennium of the simulated carbon shutoff, the carbon faded steadily. Forty percent of carbon was absorbed by the Earth's oceans and landmasses within 20 years and 80 percent of it was soaked up at the end of 1,000 years.
In studies similar to this one, Scientists usually use the scenario of emissions screeching to a stop to gauge the heat-trapping staying power of carbon dioxide.
"By itself, such a decrease of atmospheric carbon dioxide should lead to cooling," the researchers said in the study. "But the heat trapped by the carbon dioxide took a divergent track."
During the study, the simulated planet cooled for 100 hundred years at one point, then warmed 0.37 degrees Celsius during the next 400 years as the ocean absorbed less and less heat. While the resulting temperature spike seems slight, "a little heat goes a long way here."
Since pre-industrial times, the Earth has warmed by only 0.85 degrees Celsius.
The Intergovernmental Panel on Climate Change estimates global temperatures a mere 2 degrees Celsius higher than pre-industrial levels would dangerously interfere with the climate system. According to the panel, in order to avoid that point, people have to keep cumulative carbon dioxide emissions below 1,000 billion tons of carbon, about half of which has already been put into the atmosphere since the dawn of industry.
Based on the study, researchers concluded it might take a lot less carbon than previously thought to reach the global temperature scientists deem unsafe.
"If our results are correct, the total carbon emissions required to stay below 2 degrees of warming would have to be three-quarters of previous estimates, only 750 billion tons instead of 1,000 billion tons of carbon," Frölicher said in a statement. "Thus, limiting the warming to 2 degrees would require keeping future cumulative carbon emissions below 250 billion tons, only half of the already emitted amount of 500 billion tons."
The researchers' work contradicts a scientific consensus that the global temperature would remain constant or decline if emissions were suddenly cut to zero.
