New research suggests Earth had been cooling for 6,500 consecutive years before humans began releasing CO2
A new study has added to the overwhelming body of evidence that present global warming is a human-caused phenomenon.
A recent study by researchers at Northern Arizona University suggests that the world had, in fact, been cooling for the 6,500 before industrialization began to release vast amounts of CO2 into the atmosphere. The researchers used five different statistical methods to determine the global mean surface temperature (GMST) of Earth over the last 12,000 years, also known as the Holocene epoch. They found that prior to the mid 19th century, the world had been slowly cooling for 6,500 years. In fact, over the past 170 years, temperatures have surged even higher than they were before cooling began.
Professor Darrell Kaufman, who co-authored the study, said that the research might even point to 2010-2019 as being the hottest decade since before the most recent ice age, over 125,000 years ago.
The study’s authors intended to look at more recent changes in climate against the backdrop of larger temperature trends in history, as studies that look at temperature reconstruction are very important to understanding man-made climate change and convincing others of its reality. In using five different statistical methods to determine global mean surface temperature, scientists can determine much more accurate data about warming and cooling trends of the Earth, helping to identify the sources of temperature variance over time.
While the different methods yielded slightly different results, they tended to follow the same general trend. “At the multi-millennial to millennial scale, the different methods all yielded similar overall shapes according to latitude, including the relative magnitude of warming during the first two millennia, the timing of peak warmth, and the relative magnitude of the multi-millennial cooling trend that followed,” the study wrote.
The study acknowledges natural temperature variation over time, but it also identified a marked increase in temperature over a much shorter period than it took for the same amount of cooling to occur. According to Professor Cody Routson, a co-author of the study, an understanding of both man-made and natural climate change will be needed to deal with the ramifications of a warming Earth.
“Our future climate will largely depend on the influence of human factors,” Routson said. “However, future climate will also be influenced by natural factors, and it will be complicated by the natural variability within the climate system.”
