It’s winter in the Southern Hemisphere, so most of the news from the polar regions in July had to do with the Arctic and its declining sea ice. Other news included studies of the effects of aerosols on climate and new research about the aurora. Missed these stories the first time? Read on!

June 2009 set the record for the warmest global ocean surface temperature, and the combined average global land and ocean surface temperature was the second warmest since records began in 1880. Arctic sea ice cover during the same month was down 5.6% from the 1979-2000 average extent. Antarctic sea ice, on the other hand, was 3.9% above the 1979-2000 average extent. In general, the Arctic and Antarctica are responding differently to climate change.

Sea ice began to form in the Arctic approximately 47.5 million years ago, earlier than in and around Antarctica and what was previously believed. Researchers reached this conclusion based on the presence fossils of sea-ice specializing diatoms in oceanic sediment cores. Such a finding is important for reconstructing past climates in an effort to understand, model, and predict climate change today. Sea ice influences climate by directly affecting ocean-atmosphere exchanges.

NASA is currently completing a series of umanned science flights as part of an expedition to study Arctic sea ice. The remotely operated aircraft is imaging old, thick slabs of ice as they drift from the Arctic Ocean into the North Atlantic. Additional types of satellite data will help researchers better understand sea ice’s life cycle and its long-term stability.

Data collected from NASA’s ICESat (Ice, Cloud, and land Elevation Satellite) showed that Arctic ice continues to be in jeopardy. The sea ice thinned dramatically between the winters of 2004 and 2008. Younger, thinner ice is more susceptible to summer melt. ICESat provided data that enabled researchers to make the first basin-wide estimate of the thickness and volume of Arctic sea ice.

A new report from the National Research Council recommends that hundreds of Arctic sea ice images derived from classified data should be released to the scientific research community. The images show detailed melting and freezing processes and provide information that is not available elsewhere. Images were collected in the 1990s at environmentally sensitive locations around the globe, including the Arctic.

A species of arthropods known as Arctic springtails survive freezing weather by dehydrating themselves before temperatures drop. Researchers have identified a suite of genes that control the survival mechanism. They hope that understanding how animals survive in cold environments will provide innovative approaches in medical research and preservation of transplant tissue.

A new 3-D map created from radar measurements reveals ridges and furrows beneath two kilometers of ice in the West Antarctic Ice Sheet. The Rutford Ice Stream, located in the West Antarctic Ice Sheet, moves toward the coast at a rate of 1 m per day. The geologic features of the bedrock beneath the ice are both shaped by the ice stream’s movement and control its flow.

Scientists studying the aurora have long assumed that the beautiful displays were symmetrical in the Northern and Southern hemispheres. However, recent findings disprove this assumption and reveal that they can be totally asymmetric. The researchers explain that their findings are significant because it shows that data from the Northern hemisphere alone is not sufficient to understand the conditions in the less-studied Southern hemisphere. The aurora is produced by collisions of electrically charged particles with the Earth’s atmosphere. Scientists believe that electrical currents may travel between hemispheres along magnetic field lines, causing asymmetry between the two.

A special volume of the Journal of Geophysical Research reviews the growing field of “global dimming” and “global brightening.” This field studies the effects of clouds and human-generated aerosol particles on solar radiation at the Earth’s surface, which influences climate. Research also suggests a connection between global dimming/brightening and the carbon cycle – that during periods of increased aerosol and clouds, more scattered light is present in the atmosphere, enabling plants to absorb carbon dioxide more efficiently than when the air is cleaner and clearer. Further study is needed to determine the exact nature of the relationships between clouds, aerosols, and climate.

Know of another significant news story from July that you’d like to share? Reactions to one of the stories discussed here? Post a comment – we’d love to hear from you!