A scientific study on global temperature, which looked at changes over the past 11,300 years, has determined that the earth is warming up at an “unprecedented” rate. Lead author of the study, Shaun Marcott, said that the “rate of change” the scientists observed is “amazing and atypical.” The group determined that, over the past 100 years, the average temperature has increased by 1.3 degrees, whereas the last increase of that rate occurred over a period of 5,000 years. The study also found that current global temperatures are warmer than during 75 percent of the Holocene temperature history.
The study, which appeared in this month’s edition of Science magazine, was conducted by a group of four scientists from Oregon State and Harvard Universities. While climate change science deniers often argue that the earth experienced periods of extreme climate change before the influence of industrialized societies, the current study shows the rates we’re experiencing now are much more significant than in the past. According to Marcott, a geologist at Oregon State University, “The rate of change in the last 100 years is very much unprecedented compared to anything we’ve seen in the last 10,000 years.”
The scientists used a variety of land and marine-based proxy data to study temperatures over the last several thousand years, including tree ring and ocean sediment core data. The study concluded that the current global temperature is warmer than it was during 75 percent of the last 11,000+ years, but that estimate also accounted for uncertainties in the dataset. “We tried to provide a really conservative approximation of what’s going on,” said Marcott.
At the end of the last ice/glacial age, approximately 11,000 years ago, the planet began to warm up. Then, approximately 5,000 years ago, the planet began to cool again, albeit very slowly. It cooled by 1.3 degrees Fahrenheit until about 100 years ago when it drastically reversed, and the average temperature increased or warmed by 1.3 degrees. In the last century, the global average temperature has changed at the same rate that it previously took 5,000 years to reach, and, during the last 11,000 or so years, the temperature has only been higher than the current temperature during 25 percent of the time.
So, while scientists understand that our climate has gone through periods of warming and cooling, they also know that the climate change over the last 100 years has been far more extreme. And temperatures are expected to continue to heat up due to man-made greenhouse gas emissions, which increase every year.
Alisha Mims is a writer and researcher with Ring of Fire.