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?
- Debunking: A President Of The US Could Order A Nuclear Attack At A Moments Notice On A Whim
- For New President - Is Moon More Interesting Next Step For Astronauts Than Boulder Plucked From Asteroid?
- A Dimuon Particle At 30 GeV In ALEPH ??
- BPA-Free, With Regrets
- Who Is Trying To Destroy The Internet?
- Was Euclid A Black Woman? Sorting Through The False History And Bad Philosophy Of Mathematics
- You're Not Rational, Which Is Why Fact-Checking Trump And Clinton Is Not Enough
- "Okay if it is the two suns videos, those are due to offset lens reflections, most of them. Or lens..."
- "I believe in nibiru i would go as far as to say its there the videos the pictures all prove it..."
- "What is it you believe? Do you think we have two suns? Do you think there is a planet hiding behind..."
- "Haha get ready people your all about to be in for a shock then lets see who is a liar anybody want..."
- "Quite simply, the structure does not exist. What is observed is a fluctuation.BestT...."
- Kathleen Gyllenhaal: Health meets Hollywood Q&A
- How Many Genes Does It Take to Make a Person?
- To Avoid Adult Dysfunction Start 'IN UTERO'
- ACSH Medical Director Named One Of America's Top Pediatricians, We're In The Economist, And More
- The Math of Hunting and Fishing: When to Work Together
- Placebo: Bubbles Of Nothing Are Still Not Something