News from the polar regions in May includes continued trouble for Arctic sea ice and the marine mammals that depend on it for survival, research efforts in the Arctic, and analysis from the past Antarctic field season. Missed these stories the first time? Read on!

Data released from the National Oceanic and Atmospheric Administration indicates that in 2007 alone global levels of atmospheric carbon dioxide increased by 19 billion tons (0.6 percent). Carbon dioxide, the primary driver of global climate change, is released from the burning of fossil fuels and can remain in the atmosphere for thousands of years. In addition, methane levels increased by 27 million tons, the first increase in ten years. Scientists are waiting to determine whether this spike is due to melting permafrost, a permanently frozen layer of ground that stores vast amounts of carbon. As the Arctic continues to warm and thaw, the release of carbon (as methane) from permafrost could contribute to a positive feedback loop and amplify the problem.

Scientists from the University of New Hampshire and the University of Maine are headed to Denali National Park in Alaska to identify suitable sites for collecting ice cores. The fieldwork is part of a larger effort to sample ice cores from the entire Arctic region and better understand the relationship between climate change in the North Atlantic and North Pacific regions. While scientists have long believed that the North Atlantic drives global climate changes, there are now indications that changes in the North Pacific may come first, followed by a North Atlantic response. In the North Pacific, Alaska has certainly led the way in the effects of a warming climate, including coastal erosion and melting permafrost.

In an attempt to understand how North Pacific climate change affects Arctic species, six Alaskan musk ox have been outfitted with GPS collars. A research team will study the overall well-being of the animals as well as the extent to which conditions such as snow and ice events, disease, and predation drive populations.

Satellite data continues to improve our understanding about ice cover in the Arctic and its response to climate change. In northern Greenland and Canada, an international group of scientists has braved harsh environmental conditions to carry out a three-week experiment designed to validate satellite study of the polar ice cover. In addition, new University of Colorado at Boulder calculations from satellite data and temperature records give a three-in-five chance that the record low minimum extent of sea ice (set in September 2007) will be broken again in 2008. Researchers point to continued warming temperatures and the increasing extent of younger, thinner ice that is more susceptible to melting. Another study suggests that summer sunshine in the Arctic produces more pronounced melting than in the past, mainly because there is less ice to reflect solar radiation back into space. National Center for Atmospheric Research scientist Jennifer Kay explains that “a single unusually clear summer can now have a dramatic impact.” An increasingly ice-free Arctic opens up potential for cheaper and faster merchant shipping between North America and Europe.

However, the loss of Arctic sea ice is not a benefit for all. The decline of the ice puts Arctic marine mammals such as polar bears, narwhals, seals, and walruses at risk for several reasons including the availability of prey and the availability of sea ice for resting, reproduction, and avoiding predators. Shifts in the prey base would lead to changes in the body conditions and immune systems of marine mammals and the potential for increased exposure to infectious diseases. Finally, the increased human activity in an ice-free Arctic (shipping, energy exploration and development, and fishing, hunting, and tourism) may lead to new threats such as shipping accidents, contaminants, and competition for prey. Researchers also conclude that while conservation measures may reduce these secondary effects, only reducing greenhouse gas emissions will protect Arctic marine mammals and their ecosystems.

Unfortunately, those reductions don’t seem to be coming in the near future. While a recent decision by the U.S. Department of the Interior listed the polar bear as a threatened species, the announcement by Secretary Dirk Kempthorne made it clear that this listing would not be used to dictate policy about energy exploration, development, use and emissions. These disclaimers severely limit the usefulness of the listing in its ability to truly protect the species and the ecosystem on which it depends.

Marine mammals are not the only species at risk in a changing climate. In West Greenland, fewer caribou calves are being born and more of them are dying. Penn State biologist Eric Post explains that as temperatures rise, the plants consumed by expectant mothers emerge and peak earlier in the season. However, the timing of calving has not shifted, leading to a mismatch between resource availability and demand. The research is the first documentation of a “trophic mismatch” in a terrestrial mammal as a result of climate change.

The summer field season in Antarctica ended in late winter, but data from research efforts are now being published. Marine biologists have discovered a unique colony of brittlestars on the peak of a seamount (an underwater mountain) in the Southern Ocean. Dubbed “Brittlestar City,” the colony is estimated to contain tens of millions of the echinoderms and occurs in an improbable yet advantageous location. As the Antarctic Circumpolar Current is diverted over the peak of the seamount, the brittlestars are able to capture passing food simply by raising their arms. The swiftly moving water also sweeps away fish and other potential predators. Researchers studied this particular peak, and the entire Macquarie Ridge, by towing special sleds to sample organisms and an imaging system to record still images and high-definition video. Scientists believe that some of the species have never before been recorded and that some may be new to science entirely.

Scientists in the United Kingdom and Germany have been piecing together how Earth’s changing climate affected ocean chemistry about 34 million years ago. At that time, Earth experienced a dramatic shift from the warm, greenhouse conditions and higher ocean acidity of the Eocene period to the glaciated, cooler temperatures and lower ocean acidity of the Oligocene period. The researchers concluded that a fall in sea level caused by Antarctic glaciation left coral reefs stranded above tide levels. As these corals eroded, calcium carbonate was added to seawater, reducing its acidity. Scientists hope that understanding what caused this shift will help them understand and predict Earth’s response today as the levels of greenhouse gases increase and oceans become more acidic.

The ANDRILL (Antarctic Geological Drilling) project has added 1,139 meters of “new” sediment cores to a collection housed at Florida State University’s Antarctic Marine Geology Research Facility. Scientists will use the cores to examine changes in Antarctica’s ice sheet and marine and terrestrial life during a period of significant cooling that occurred between 20 and 14 million years ago. Correlating this record to existing data and climate models will help scientists understand how local changes in the Southern Ocean relate to regional and global climate events and will provide insight into Antarctica’s potential responses to future global climate change.

The most recent analysis of trace gases trapped in Antarctica’s ice provide a reasonable estimate of greenhouse gas concentrations as much as 800,000 years in the past – about 150,000 years more than previous studies. The research shows that during the entire period of time, there have never been concentrations of carbon dioxide and methane as high as the current levels. In addition, the study continues to provide a strong correlation of methane and carbon dioxide and temperature. Researchers hope to ultimately extend the data as far back as 1.5 million years.

New research by scientists at the National Center for Atmospheric Research has found that computer analyses of global climate change have consistently overstated warming in Antarctica. By comparing climate records from the past 50 to 100 years with computer-run simulations, scientists found that most of Antarctica has not warmed as much as the rest of the globe. The explanation for this difference? The ozone hole, an environmental issue that first made headlines in the 1980s. The lack of ozone over Antarctica chills the middle and upper atmosphere and alters wind patterns in such a way that prevents warmer air from reaching these areas. Ironically, scientists believe that a full recovery of the ozone hole may lead to another environmental problem: the modification of climate change in the Southern Hemisphere and an amplification of Antarctic warming. However, the extent of this potential effect will be largely affected by the rate of greenhouse gas emissions. It is not clear how warming in Antarctica would affect sea-level rise. NCAR researcher Andy Monaghan explains that “over the next century, whether the ice sheet grows from increased snowfall or shrinks due to more melt will depend on how much temperatures increase in Antarctica, and potentially on erosion at the ice sheet edge by the warmer ocean and rising sea level.”

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