For eons a giver of life, sunlight is being turned into a force for death by the carbon collecting in the atmosphere. A new study suggests the planet is warmer than it’s been in 11,300 years, and temperatures will climb to increasingly dangerous levels through 2100.
The study, published in Science, shows “a sharp upward temperature trend over the past century after more than a thousand years of relatively flat temperatures,” Climate Central reports. But the new analysis extends the timeline much further back, using evidence from seafloor and lake sediments to determine past temperatures.
—Posted by Alexander Reed Kelly.
The research aimed to understand whether the current warming is unprecedented in the Holocene period, or whether the same thing might have happened before, because of purely natural causes.
Based on the evidence, it has not. Since the ice sheets departed, the warming trend was found based on the chemical composition of ancient shellfish called foraminifera, variation in types of pollen extracted from lake sediments and other temperature-dependent measures. The data shows there was a long, gradual warmup for about 5,000 years, then a plateau of warm temperatures, and then an equally gradual cooling trend until about 200 years ago.
Marcott said that is in line with the gradual changes known as Milankovitch Cycles, caused by the Earth’s tilt and its orbit around the Sun. Based on where we are in those cycles, Marcott said, the planet should still be cooling. Not only is the Earth warming, it is warming much faster than a Milankovitch Cycle could possibly explain. “The temperature change is both too abrupt, and going in the wrong direction, to be natural” Marcott said.
VinothChandar (CC BY 2.0)