The Pace of Climate Change: Half of Warming Occurs Within First 10 Years

How fast is climate change happening? That's a good question. A great deal of research has focused on the amount of warming that has resulted from increased greenhouse gas concentrations. Yet very little has examined the pace of change following these increases. Now, scientists have uncovered what this pace is, revealing that about half of the warming occurs within the first 10 years after an instantaneous step increase in atmospheric CO2 concentration.

In order to examine climate change a bit more closely, the researchers brought together the results from the majority of the world's leading climate models. In all, the scientists analyzed more than 50 climate simulations, which were performed using 20 different climate models. In the end, they found a fairly high degree of consensus on the general character of the pace of climate change.

That's not to say that there isn't some disagreement, though. For example, one model reaches 38 percent of the maximum warming in the first decade after a step increase in CO2 concentration. Another model reaches 61 percent of the maximum warming in this time period. Similarly, one model reaches only 60 percent of maximum warming in the first century after the step increase, while another achieves 86 percent.

"While there is substantial uncertainty in both the pace and change and the ultimate amounts of warming following an increase in greenhouse gas concentration, there is little uncertainty in the basic outlook," said Ken Caldeira, one of the researchers, in a news release. "If we continue increasing atmospheric CO2 concentrations with emissions from the burning of coal, oil and gas, the Earth will continue to get hotter. If we want the Earth to stop getting hotter, we have to stop building things with smokestacks and tailpipes that emit CO2 into the atmosphere."

In all, the researchers found that about half of warming occurs within the first 10 years after an instantaneous step increase in CO2. About one-quarter of the warming occurs more than a century after this increase. While there is uncertainty, though, the research does show how important it is to regulate gas emissions.

The findings are published in the journal Environmental Research Letters.