A quick primer for the climate impaired The natural presence of certain gases like carbon dioxide in the air helps keep the Earth warm enough for life to exist. Solar radiation warms the planet, and these gases slow the loss of that heat back into space. They act somewhat like glass in a greenhouse, hence the nickname. In the past, when the level of CO2 rose -- maybe due to vast rotting swamps or volcanic action -- the climate grew warmer. Sometimes much, much warmer. And when CO2 levels plunged? Can you say ‘Ice age'? After thousands of years of relative stability, Earth's CO2 concentration has lately been rising fast, in synch with the burning of fossil fuel by industrialization and the emissions of modern life. The Earth's CO2 level is now almost 390 parts per million, according to the latest measurements posted by the Mauna Loa Observatory in Hawaii. So, when was the last time CO2 concentrations were that high? About 15 million years ago, according to this 2009 study led by UCLA scientist Aradhna Tripati. A very different Earth, that. Global temperatures were 5 to 10 degrees warmer, and there was no permanent ice in the Arctic. Sea level was at least 75 feet higher. This could be our future.

A series of warmer summers and drier springs in Interior Alaska has forced wildfires to burn deeper into the region's ancient peat, releasing far more carbon dioxide into the air than previously thought, according to a new study by a team of scientists.

The longer-burning fires, and longer burn season, has dramatically increased the release into the atmosphere of carbons stored over eons by Alaska's black spruce ecosystem, a dynamic that threatens to accelerate global warming even more.

The result may be a climate game-changer.

Alaska's boreal forests -- long thought to be one of the Arctic's main carbon sinks and a stabilizing influence against global warming -- have begun to spew out more greenhouse gas than they take in, according to a study by University of Guelph plant biologist Merritt Turetsky, of Ontario, Canada, and six other researchers.

"Essentially this could represent a runaway climate change scenario in which warming is leading to larger and more intense fires, releasing more greenhouse gases and resulting in more warming," said lead author Turetsky, in a release about the study, to be published in Nature Geoscience. "This cycle can be broken for a number of reasons, but likely not without dramatic changes to the boreal forest as we currently know it."

Study co-author Eric Kasichke, a professor of biogeography at the University of Maryland, said the research amounts to the first demonstrated link between burned area and increases in fire severity. "This not only impacts carbon storage, but also will accelerate permafrost loss and changes in forest cover," he added.

The findings dramatize the critical role the Arctic plays in global climate change, driven by the increasing concentration of atmospheric greenhouse gases produced by human activity and the burning of fossil fuel.

Measured over decades, the North has seen shifts in sea ice, snow cover, vegetation, wildlife, permafrost and air temperature.