News from the polar regions during June included reconstructions of past climates and carbon dioxide levels, changes in the Greenland ice sheet, and impacts of climate change on Arctic people and mammals. Missed these stories the first time around? Read on!

Researchers analyzing plankton shells have reconstructed carbon dioxide levels over the past 2.1 million years. While the findings confirm that higher carbon dioxide levels coincided with warmer intervals, it did not confirm the idea that a drop in CO2 levels caused the Earth’s ice ages to grow longer and more intense about 850,000 years ago. The long greenhouse gas record also shows that today’s carbon dioxide levels (about 385 parts per million) caused by industrialization are even more unusual when compared with the much lower levels of the past.

In addition to determining prehistoric global carbon dioxide levels, researchers want to reconstruct past climates. Researchers turned to marine sediment cores containing pollen and spores to document the changes in ancient land plants in the northern latitudes during the Late Eocene and Early Oligocene, approximately 33.5 million years ago. Figuring out what happened during previous periods of climate change may help scientists more accurately predict the changes in today’s warming world.

53 million years ago, ancient mammals such as tapir ancestors and rhino cousins lived above the Arctic Circle in a much milder climate featuring lush, swampy forests. A new study shows that the animals inhabited the High Arctic year round, enduring six months of darkness each year.

Fieldwork on a prehistoric glacier in the Canadian Arctic shows that modern glaciers (like those that make up the Greenland and Antarctic ice sheets) are capable of shrinking, or retreating, quite rapidly – something that could greatly impact sea level rise. Researchers said the findings are especially relevant to the Jakobshaven Isbrae, a Greenland glacier. The Greenland ice sheet is melting faster than expected and may be responsible for nearly 25 percent of global sea level rise in the past 13 years, concludes a new study of precipitation and ablation (evaporation, melting, and calving) of the ice sheet. Ice melt contributes to sea level rise and also changes the salinity of the oceans, which can affect ocean ecosystems and deep water mixing. If Greenland’s ice continues to melt at least a moderate rate, cities on the northeast coast of North America may be at an increased risk.

In early June, scientists gathered to discuss a short-lived Arctic pollutant: soot from large-scale springtime agricultural burning in Russia, Kazakhstan, China, the U.S., Canada, and the Ukraine. Black-colored soot is transported to the Arctic via global circulation patterns, where it absorbs solar energy and leads to accelerated melting of snow and ice. It may account for as much as 30 percent of Arctic warming to date. Targeting these types of emissions in addition to greenhouse gases will provide health benefits as well as faster temperature response.

Polar research often involves long distance air travel, icebreakers, and snowmobiles – technologies that all release greenhouse gases. One Canadian researcher is challenging his peers to consider ways to reduce their research’s carbon footprint. Even though the polar research community is relatively small, he feels that such critical evaluation is important given the emphasis on climate change and greenhouse gases in both research and the media.

As Arctic sea ice declines, debate over ownership of the ocean grows. One important consideration is that different cultures and countries hold different understandings of geography that color territory claims. A professor of geography explains that while some countries view the Arctic Ocean as land covered by water (and thus seek to lay claim to that land), others view the area as just water to be passed over during travel (and thus view it as accessible to all). These types of implicit assumptions can spark disagreements and complicate debate over these emerging territories.

As the Arctic warms, permafrost thaws, releasing carbon into the atmosphere. At the same time, plants will flourish in the warmer environment, taking in carbon as they grow. While researchers hoped that increased plant cover would be able to compensate for the thawing permafrost, new research shows that if warming continues, that will not be the case. While tundra plant growth may initially keep up with increased carbon emissions, the plants will become overwhelmed and unable to take in all the carbon if thawing continues.

In previous months, we’ve discussed the effects of climate change on the Arctic’s Inuit population: coastal erosion, sea level rise, and permafrost thaw. A paper presented at the 2009 Congress of the Humanities and Social Sciences conference argues that while reducing greenhouse gas emissions continues to be important, there is a global responsibility to help vulnerable Arctic communities adapt to the changing environment.

New water quality research from the Mackenzie River Delta shows a much higher level of mercury than previously determined. Most man-made mercury pollution comes from coal-burning power plants across the globe. Atmospheric circulation patterns transport the airborne particles to the Arctic, where they enter the water supply and show up in fish muscle. Arctic communities that depend on fish and whale meat for a large percent of their diet are especially vulnerable to the neurotoxin’s effects.

U.S. Fish and Wildlife reports confirm that Alaskan polar bear populations are declining and that Pacific walrus populations are under threat due to loss of their sea ice habitat. The polar bear is currently listed as threatened under the Endangered Species Act, and the Fish and Wildlife Service is under court order to make a finding on a petition to protect the Pacific walrus by September 10 of this year. Sea ice, which is the habitat of both species, is rapidly declining as a result of climate change.

Canadian researchers may be able to more accurately monitor the polar bear population thanks to a new three-pronged approach. First, researchers will collect bits of hair via “hair traps,” or fenced enclosures baited with meat. This hair will be genetically analyzed to determine the number and sex of the bears. Second, samples of bear feces will be screened for disease causing agents. Finally, Inuit hunters will identify a bears’ sex, age, and size from its footprints. These findings will be combined to map the population’s age and sex distribution, diet, movement, and mating patterns in a non-intrusive and more cost effective manner than traditionally used aerial surveys.

An unmanned aircraft has been launched to search for ice seals at the southern edge of the Bering Sea pack ice. The remote habitat is challenging, expensive, and potentially dangerous to navigate using traditional means.

Warming is also affecting caribou and reindeer – population numbers have dropped almost 60 percent in the last three decades. Warming temperatures cause earlier greening (before migrating herds arrive north), depriving mothers and calves of adequate feeding. Warmer summers mean increased insect activity, also interfering with normal feeding. Finally, freezing rain in winter covers lichens that serve as an important food source for the animals.

Know of another important news story from June that you’d like to share? Have a comment about one of the stories mentioned above? Post a comment – we’d love to hear from you!