Observations from both satellites and the Earth’s surface are indisputable — the planet has warmed rapidly over the past 44 years. As far back as 1850, data from weather stations all over the globe make clear the Earth’s average temperature has been rising.
In recent days, as the Earth has reached its highest average temperatures in recorded history, scientists have made a bolder claim: It may well be warmer than any time in the last 125,000 years.
Tracing climatic fluctuations back centuries and millennia is less simple and precise than checking records from satellites or thermometers. It involves poring through everything from ancient diaries to lake bed sediments to tree trunk rings.
But the observations are enough to make paleoclimatologists, who study the Earth’s climate history, confident that the current decade of warming is exceptional relative to any period since before the last ice age, about 125,000 years ago.
Our understanding of conditions so long ago is far less detailed than modern climate data, meaning it’s impossible to prove how hot it might have gotten on any given day so many thousands of years ago. Still, the Earth history gleaned from fossils and ice cores shows the recent heat would have been all but impossible over most of those millennia. [Continue reading…]