It's cold and snowy just about everywhere except where you expect it. Ice in northern Alaska’s lakes during winter months is on the decline, as shown by twenty years of satellite radar imagery demonstrating how changes in our climate are affecting high-latitude environments - at least in the last few decades.
Changes in air temperature and winter precipitation over the last five decades have affected the timing, duration and thickness of the ice cover on lakes in the Arctic. In this region, warmer climate conditions result in thinner ice cover on shallow lakes and, consequently, a smaller fraction of lakes freezing all the way through during winter months.
These changes in ice cover affect the local and regional climate, the dynamics of the underlying permafrost and the availability of water for residential and industrial use throughout the winter. They also alter the physical, thermal and chemical properties of the water, affecting the ecology dependent on them.
A recent study of Alaska’s North Slope documented the ice regimes of shallow lakes using radar images from ESA’s ERS-1 and -2 satellites. The study reveals a 22% decrease of ‘grounded ice’ – or ice frozen through to the lakebed – from 1991 to 2011. This is equivalent to an overall thinning of ice by 21–38 cm.
“Prior to starting our analysis, we were expecting to find a decline in ice thickness and grounded ice based on our examination of temperature and precipitation records of the past five decades from the Barrow meteorological station,” said Cristina Surdu, lead author of the study. “At the end of the analysis, when looking at trend analysis results, we were stunned to observe such a dramatic ice decline during a period of only 20 years.”
The greatest change was observed during late winter (April–May) over the 20-year period, which gradually decreased from 1991 to 2005. The ice experienced a more abrupt decline during the final six years of the analysis, reaching its lowest in 2011.
Radars such as those on the ERS mission can ‘see’ through clouds and in the dark, providing continuous imagery over areas like northern Alaska that are prone to bad weather and long periods of darkness.
How the radar signals bounce back can also be used to determine if the lake ice was grounded or ‘floating’ (with water underneath).
ERS-1 operations ended in 2000 and ERS-2 retired in 2011. While radar imagery from these two satellites, as well as from the Envisat mission – which ended in 2012 – allowed adequate monitoring of freezing lakes, continued coverage would improve the investigation of ice regimes at high latitudes.
The upcoming Sentinel-1 mission of the Copernicus programme will provide more frequent coverage of this area while ensuring global continuity of radar acquisitions for operational lake-ice monitoring. The first of this two-satellite mission is set for launch this spring.
Citation: Surdu, C. M., Duguay, C. R., Brown, L. C., and Fernández Prieto, D.: Response of ice cover on shallow lakes of the North Slope of Alaska to contemporary climate conditions (1950–2011): radar remote-sensing and numerical modeling data analysis, The Cryosphere, 8, 167-180, doi:10.5194/tc-8-167-2014, 2014
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Researchers Created A Laser Bullet To See What It Would Look Like - And Here It Is
- Great Earthquakes Doubled In The Most Recent 10 Year Period - What That Means
- What Americans Fear Most Isn't Ebola Or Terrorism, It's...
- ECFA Workshop: Planning For The High Luminosity LHC
- The Comets Of Beta Pictoris
- Slavery In America: Back In The Headlines
- As The Weather Changes, So Do Beliefs About Climate Change
- "It would be very useful, if also deeply depressing, to collect all of the statements made by prominent..."
- "Trying to explain this to people can be infuriating. It really is a few of us arguing against..."
- "Hi Valerie, thanks for writing.If you look up papers on existential dread, you should find some..."
- "If journal articles like this one would reference the science and the data instead of the politics..."
- "people, the claim that: 1 you do not believe in god, 2 you exist QED atheists exist is fatuous..."
- National Wildlife Refuge System bans on GMOs and neonics lack transparency, scientific rationale
- Want better sperm? Eat more pesticides
- Beyond universal donors, some people are programed with no blood type at all
- Anti-conventional ag movement spurs Big Ag to look to organic pesticides
- Can people really inherit memories?
- An end to fat shaming? The 50 year DNA mystery of metabolic dysfunction may soon be solved
Books By Writers Here