Washington, July 1 (ANI): Man made global warming is not a recent phenomenon, but one that started when ancient hunters roamed the planet, suggests a new study.
The study claims that massive killings of mammoths lent to the planet's warming.
According to Doughty, Adam Wolf, and Chris Field-all at Carnegie Institution for Science - normally, mammoths would have grazed down any birch that grew, but if the mammoths vanished, the birch could spread.
The tress would change the landscape's colour making it much darker so it would absorb more of the Sun's heat, in turn heating up the air. The climate grew hotter, making it harder for the mammoths to cope, and spreading the birch growth further.
The researchers found that around 15,000 years ago-the same time that mammoth populations dropped, and that hunters arrived in the area-the amount of birch pollen started to rise quickly.
Doughty and colleagues then used a climate simulation to estimate that this spread of birch trees would have warmed the whole planet more than 0.1 degrees Celsius.
The study is published in Geophysical Research Letters. (ANI)