Arctic sea levels fluctuate as ice decreases

Arctic sea ice levels are becoming more unstable according to an article published by The National Aeronautics and Space Administration (NASA) in its Science News blog on Oct. 15.

The article summarized the research up to this point and identified current and future research efforts. Intensive monitoring of arctic sea ice levels began in the 1970s and revealed little decline until 2005 when sea ice levels began fluctuating more profoundly and experiencing a net year-to-year decline.

This dramatic change in sea ice levels may be due to the fact that while researchers were measuring the area covered by sea ice, the ice sheets may have been thinning — ice thickness not being something extensively studied at the time. This would explain the sudden, unexplained deterioration of sea ice coverage in 2005, years after other indicators of climate change Had already shown deterioration.

Coverage has continued to decline on average. At one point in 2014, the edge of the sea ice reached within five degrees of the North Pole.

Decreased sea ice coverage has a compounding effect as dark ocean water absorbs more solar energy than white ice sheets. The magnitude of this effect is not well understood, however, because the heating of the ocean also produces clouds, which in turn reflect sunlight.

The magnitude of the compounding melting effect depends on the reflectivity of the clouds, both to incoming sunlight and radiation from the ocean that world normally escape into space.

To gain understanding of the effect, NASA will conduct an airborne study titled the Arctic Radiation-Ice-Bridge Sea and Ice Experiment (ARISE). The mission will use a Lockheed C-130 Hercules outfitted with sensors designed to measure the effects of clouds and the ice sheet itself, including upward and downward radiometers, an infrared thermometer and a laser altimeter. Together the sensors will measure incoming and outgoing radiation, ocean temperature and ice sheet thickness.

Currently, there are no satellites in orbit collecting intensive data on polar ice sheets. The Ice, Cloud and Land Elevation Satellite (ICE Sat), launched in 2003, stopped collecting scientific data in 2009. Its replacement, ICE Sat-2, will not be launched until 2016. ARISE was founded in 2009 to fill this gap in data collection. Data from ARISE, which measures more variables than a satellite study, will be used to interpret the data from ICE Sat-2 more accurately. The satellite data will cover a more comprehensive area.

The ARISE program has had success in the past. Since autumn 2009, ARISE has conducted an autumn mission in the Antarctic and a spring mission in the Arctic. The 2013 Antarctic mission marked the first time flights were based from a runway in Antarctica itself.

ARISE will allow researchers to understand and predict the rate at which ice sheets are shrinking, as well as the effects that a complete disappearance of the ice sheet would have on climate.