Global warming has been gaining momentum over the last few decades, and increases in temperature will accelerate throughout the century even if greenhouse gas emissions are cut back, a new study suggests.
Looking at longer intervals—40 years at a time—researchers were able to disentangle normal fluctuations in temperature from those due to actual climate change, according to the report published in Nature Climate Change on Monday.
"At that length of time, the human-forced trend comes out of the noise," said the study's lead author, Steven Smith, a senior researcher at the Department of Energy's Pacific Northwest National Laboratory. "Looking at shorter periods, such as 20 years, it's harder to see over the natural variability."
Smith and his colleagues determined that even if greenhouse gas emissions were cut back to where they were in the year 2000, climate change would continue to accelerate throughout the century. If the emissions aren't cut back, changes will occur far more rapidly.
In either case, humanity will need to find ways to adapt to the changing climate, Smith said.
The researchers looked at rates of temperature change over the last 2000 years based on what has been gleaned from changes in tree rings, corals, and ice cores. They compared that information to what occurred between 1850 and 1930, a period when the amount of fossil fuel gases collecting in the atmosphere was low.
In models that looked at what might occur through the end of this century, those data were compared to what has happened over the last 40 years.
"I don't think it's a doom and gloom scenario, but it's certainly a little sobering," Smith said. "We've known for some time that what we put in place now we're going to experience for the next few decades due to inertia in the system."
So what does this mean for humanity?
"The bottom line is that we don't really know what we are in for," Smith said. "What is normal is changing more rapidly than previously thought. We are going to have to figure out how to adapt."