Today NPR reported that a team of scientists has created a record of global temperatures dating back to about 11,000 years ago. The purpose of compiling the data was to determine whether or not current global warming trends mirror trends experienced by mammoths and saber-tooth beasts at the end of the last ice age. The study's results confirmed that the planet's present rates of temperature increase are unusual.
Researchers used a variety of means to gather the data. Ice core samples revealed the temperatures in polar regions for the last 2,000 years. Tree rings from around the world allowed scientists to determine temperatures elsewhere on a similar time scale. A sampling of tiny, fossilized shells from ancient sea-dwelling foraminifera provided data from older time periods.
Geologist Shaun Marcott from Oregon State University said, “Global temperatures are warmer than about 75 percent of anything we've seen over the last 11,000 years or so." Current temperatures were also noted to be higher than the past 4,000 years. However, Marcott warned, "It's really the rates of change here that's amazing and atypical."
After the last ice age, the planet has experienced a few drastic changes in temperature, warming, cooling and then warming again. The team noted that in the past it took an average of 5,000 years for the average global temperature to change by 1.3 degrees; the same change in average global temperature experienced in the last 100 years.
Climate researcher Gavin Schmidt from NASA's Goddard Institute for Space Studies shared what he refereed to as “a sobering thought.” He said, “The climate changes to come are going to be larger than anything that human civilization and agriculture has seen in its entire existence.”
Scientists estimate that temperatures will meet or exceed that of the warmest modern geological era, the Holocene, later this century. Researchers also believe that the human-created greenhouse gases will likely prevent the refreezing of the Northern Hemisphere which would occur if climate changes were still governed by natural factors.
The team's study was published in the journal Science.