Image courtesy of the Niels Bohr Institute/University of Copenhagen
New data obtained from an analysis of trace gases locked in Antarctic ice cores has revealed that atmospheric GHG levels are at their highest point in the last 800,000 years. The results of the analysis, published in the latest edition of the journal Nature, have also shown that current methane levels are at a record high -- 134% above prehistoric highs. Carbon dioxide levels are 24% higher now than at any other period sampled by the cores. Scientists are able to glean information about past levels of trace gases in the atmosphere by studying tiny bubbles of air trapped in the Antarctic ice cores. Furthermore, they also allow them to gain a better understanding of the planet's natural climatic fluctuations, the forces that shaped them and the possible implications for our own climate.
With that in mind, the study's worrying, though not unexpected, findings hinted at a continuation of present climatic trends well into the future: Levels of carbon dioxide and methane, which stand at a little over 380 parts per million (compared to roughly 200-300 ppm during the last 800,000 years) an 1,800 parts per billion (compared to 400-700 ppb in the past), respectively, are "off the charts."
Extended periods of warmth always coincided with high atmospheric GHG levels during this period. That means we're currently in an "interglacial" period; in the past, these have typically lasted 10,000-20,000 years. Scientists aren't predicting a return to a long, cool glacial period any time soon though the growing likelihood of an abrupt climate change incident, operating on a much shorter time scale, could raise that possibility.
The results of this study, conducted by the European Project for Ice Coring in Antarctica, extend scientists' understanding of prehistoric GHG levels another 150,000 years back. The researchers hope to eventually obtain data going as far back as 1.5 million years.
Edward Brook of Oregon State University, the author of a Nature commentary on the findings, concluded that, "today's concentrations of these greenhouse gases have no past analogue in the ice-core record," and that the "remarkably strong correlations of methane and carbon dioxide with temperature reconstructions also stand."
Via ::ScienceDaily: Ice Cores Reveal Fluctuations In Earth's Greenhouse Gases (news website)