Earth is the warmest it's been in 120,000 years
Tuesday, September 11, 2018, 5:17 PM - Earth is warming and that's a demonstrated fact, but what is astonishing is that we are now living temperatures from the past, values that where measured around 120,000 years ago.
Many of you are probably wondering how scientists are capable of reconstructing temperatures that occurred thousands of years back?
Well, there are several methods to do so, from sediment, fossil tree ring analysis, to what appears to be one of the more commonly used techniques -- air analysis from bubbles trapped in ice. A thorough analysis of the air composition in those bubbles trapped in ice many feet below the surface can provide detailed information about what the earth's temperature could have been then.
July temperature anomoly. Image courtesy of NOAA.
A few weeks ago, NASA scientists announced that July 2018 had just made it to the podium of the warmest July's, becoming the third warmest after 2016 and 2017 since temperature records began back in 1880. At about the same time, Stefan Rahmstorf, a scientist in the Institute of Climate Impact at the University of Postdam, Germany, revealed that, since July is the warmest month of the year, July 2018 had become one of the warmest months on record since the geological period known as the Eemian Riss/Würm period.
Ice core courtesy of NASA.
The Eemian occurred between 115,000 and 130,000 years ago and it was warmer than now, with average temperature values 1.5 to 3.0oF above what we experience today. Those warm years, together with the prior and post glacial periods, occurred naturally, with no human influence, solely modulated by the climate cycles of the earth and our then position with respect to the Sun.
More evidence from the past shows a big difference with respect to how temperatures change today. Back then, it appears that periods of warming and cooling occurred gradually over thousands of years. However, the rapid warming we have experienced on Earth over the past 150 years has no similarities with the past. Modern time thermal changes are clearly linked to human activity caused by a frantic use of fossil fuels and consequently an increase in greenhouse gas concentrations (mainly carbon dioxide).
Vostok Icecore Temps and CO2 NASA
Vostok Ice Core: Temps and CO2 courtesy of NASA.
Paleoclimatologist Patrick Bartlein from the University of Oregon, has been studying temperature changes on Earth in detail since the glacial period. He, and other experts in the field, have no doubt Earth is going through the warmest climate period of the past 120,000 years. Temperatures today are even higher than during the warmest period of the post-glacial era, the Holocene, which occurred 7,000 years ago.
In the School of Forestry and Environmental Studies at Yale University, Jennifer Marlon also follows closely the intense heat registered in our planet over the past decade. Among her findings, one solid piece of information stands out, during the warmest period of the Holocene, it was only the Northern hemisphere that experienced warm summers. Today, positive temperature anomalies are all over the place and they last all year around.
While Earth continues to warm at an accelerated rate due to anthropogenic causes, scientists from a good number of research institutions point out that the natural climate cycle of our planet, could be moving towards a climate scenario similar to what characterized the warm Eermian period. If that is case, our future would be one of a much warmer climate, with higher sea levels caused by massive ice melt and ocean water expansion.
Alaska Glaciar Melt.
The big difference between the Eemian back then and the one that could be on the way is mainly carbon dioxide (C02) concentrations in our atmosphere. Today's concentrations are the highest of the last 800,000 years, with values in the order of 409 parts per million. During the Eemian, those numbers where considerably lower at around 280 parts per million.
Courtesy of NASA.
We have now known for years, that C02 can trap heat, and that an atmospheric increase of its concentration, compared to how it occurred thousands of years ago, is completely anti-natural. With so much carbon dioxide in the atmosphere, we also know that global temperature values will continue to escalate, but, how much would that increase accelerate if it were to occur in an Eemian type climate?