Scientists: Earth is warmer today than any time in the past 11,300 Years
Science Recorder, Delila James
Earth is getting warmer.
It’s a significant finding in the world of climate science.
Comprehensive new research into global climate change finds that our planet is warmer today than at any time during the last 11,300 years. The study, published in the journal Science, examined variations in temperature over the past 15,000 years, during the relatively warm Holocene period, which began at the close of the last great ice age and continues to the present day.
Researchers from Oregon State University and Harvard used core samples from 73 ice and sediment core monitoring sites around the globe to reconstruct global temperature change by studying fossils of marine microorganisms.
Previous climate histories have mainly focused on changes over the past 2,000 years, but the new data puts today’s climate change into a much broader and long-term context, according to lead author on the study, OSU paleoclimatologist Shaun Marcott.
Earlier studies have relied primarily on analysis of tree rings, lake sediment cores and isotope ratios in cave formations. Although such studies can provide detailed reconstructions of climatic change, they typically apply only to limited geographical regions and do not extend back more than a couple of thousand years, says Marcott. Marcott’s study, on the other hand, fills in the crucial post-ice age time during early human civilization.
In addition, the study represents one of the first attempts to build a set of data from sites around the world. Peter Clark, an OSU paleoclimatologist and co-author on the Science article, said many previous temperature reconstructions were regional in nature and were not placed in a global context, which led the team to create a model that was global in context.
The evidence shows a downward trend of temperatures that reversed 100 years ago, indicating Earth was either heading toward a mild ice age in the years 1550 to 1850, or it was continuing to cool naturally. Then the advent of the industrial revolution and the emission of greenhouse gases from the burning of fossil fuels seemed to reverse the trend.
Scientists say solar radiation increased in parts of the world due to a shift in the Earth’s orbit about 12,000 years ago. After about 6,000 years, the planet began to cool — until about 200 years ago, when temperatures began rising steadily. The new evidence seems to warn of a dramatic warming trend that further bolsters the notion that the rise in modern-day temperatures is not a natural phenomenon, but rather a result of man-made carbon dioxide emissions.
The study shows the recent heat spike “has no precedent as far back as we can go with any confidence, 11,000 years arguably,” said Pennsylvania State University professor Michael Mann, who was not involved in the research. He said scientists may have to go back 125,000 years to find warmer temperatures potentially rivaling those of today.
Marcott’s research reinforces what most scientists generally believe: that the earth is warming at an unprecedented rate and that human beings are the main reason for the rise in global temperatures. Since the industrial revolution, mankind has gained the power to directly impact its climate system through the release of large quantities of carbon dioxide and other greenhouse gases
It remains unclear whether the study will begin to pressure policy makers around the world to take action to curb greenhouse gas emissions. Speaking in late 2012, a coalition of investors from around the world called on national governments to increase action on climate change and boost clean-energy alternatives or risk trillions of dollars in investments and disruption to economies. Just one month earlier, major U.N. climate talks in Doha, Qatar, failed as nearly 200 nations met in an attempt to extend the Kyoto Protocol, the existing plan for curbing greenhouse gas emissions by developed nations that runs to the end of 2012.
Already a number of international meetings have failed to produce action on curbing climate change emissions. The failure has led a number of skeptics to question whether international coalitions are effective into today’s globalized world, where countries — such as China and India — are competing to raise living standards for an emerging middle class that relies heavily on economic growth as a path to prosperity.
That said, the study is likely to be met with skepticism from individuals questioning whether human action is behind warming trends, and whether warming trends are actually occurring. The Science study comes just weeks after researchers in Norway announced findings that seem to support the notion that global warming is less severe than previously predicted by the United Nations climate authority. The study also found that meeting targets for minimizing global warming may be more achievable than previously thought.
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