Glacier Ice Loss in Alaska Overestimated; Rate Nonetheless Doubled over Past 40 Years
04.03.2010 - Atmosphere & Space, Water & Oceans, Ice & Snow, Arctic
According to a new study featured in Nature Geoscience that recalculates glacier melt in Alaska, previous studies might have largely overestimated mass loss from Alaskan glaciers over the past 40 years. The study shows that Alaskan glacier melts between 1962 and 2006 actually contributed about one-third less to sea-level rise than previously estimated (0.17mm instead of 0.12mm). Although relatively small, these figures add up over decades and do not take into account the massive ice sheets over Antarctica and Greenland.
Following the study, two major factors could be the reason behind the original miscalculation:
- the impact of thick deposits of rock debris protecting the ice from solar radiation and melting
- not taking into consideration that ice along the edges of glaciers is thinner
The researchers took data from the French SPOT 5 satellite and the NASA/Japanese ASTER satellite and converted the optical imagery to elevation information and compared it to the topographical series maps of glacial elevations dating back to the 1950s. While this study determined a lower rate of ice loss over a period spanning over 40 years, other studies have demonstrated the rate of ice loss to have more than doubled over the past two decades. This substantial increase in ice loss during the 1990s causes the current sea level to rise by 0.25mm and 0.30mm on an annual basis, more than twice the average rate for the last 40 years.
