A group of scientists have refined the famous 'hockey-stick' graph, adding nearly 10,000 years of data onto it, and highlighting the alarming trend in global warming in the past few decades.
This new study, published in the March 8th edition of Science, expands the timeline of the 'hockey-stick' graph — originally produced by climate scientist Michael Mann in the late '90s — which showed global temperature anomalies (when the planet was warmer or cooler than normal) over the past 1,500 years or so.
The new graph, produced by scientists at Oregon State University and Harvard University, expands the timeline to 11,300 years before the present, and shows the much longer trend of Earth's temperatures.
Now, this graph shows that there have, indeed, been periods of time when temperatures were as warm as (possibly warmer than) they are now, however, the temperature anomaly itself isn't really the alarming part.
As the second graph shows, Earth has been on a general cooling trend for roughly the past 7,000 years, reaching a minimum around 250 years ago. After that, temperatures started to rise at a fairly sedate rate, until just around 75 years or so ago, when they shot upward at an incredible rate.
“We were on this downward slope, presumably going back toward another ice age,” said study lead author Dr. Shaun Marcott, according to The New York Times. Marcott is a palioclimatologist at Oregon State University.
"What we found is that temperatures increased in the last hundred years as much as they had cooled in the last six or seven thousand," said Marcott, according to Mother Jones. "In other words, the rate of change is much greater than anything we've seen in the whole Holocene." The Holocene is the current geologic period, which started around 12,000 years ago and runs up to the present.
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Another way of looking at it is: the last time that temperatures rose by this amount, it took the Earth over 4,000 years to accomplish it on its own. Apparently, with our 'help', that same rise in temperature has taken only about a century or so, and therein lies the problem. Plant and animal species (including us) can adapt to changes in the climate, but that adaptation takes a long time to accomplish. The last temperature increase happened over such a long period of time that everything had plenty of time to adapt. This new temperature rise is happening at a rate that will make adaptation extremely difficult (even for us).
"We and other living things can adapt to slower changes," said Dr. Mann, according to The New York Times. "It's the unprecedented speed with which we're changing the climate that is so worrisome."
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