Watching Alaska Change from Space: What Landsat Does for the Largest State

Alaska's landscapes are changing faster than those of the lower 48. Aerial surveys, flown biannually over the rest of the country, cost too much for a state this big. That leaves the Landsat land-imaging satellites as the only publicly available, up-to-date imagery of the state's land — and the basis for many public and private decisions about adapting to a changing landscape.

A big, changing state

At 663,268 square miles, Alaska is the largest U.S. state, and much of it is remote, thinly populated and hard to reach for fieldwork. From orbit, Landsat can watch it all.

• A USGS-led study found that 13% of Alaska's land — an area larger than Wisconsin — had changed over 32 years: glaciers retreating, shrubs and the tree line spreading, wildfires, erosion, pollution and more (Pastick and others, 2019).
• In 2015, Landsat was used to map Alaska's near-surface permafrost and project how it will thaw (Pastick and others, 2015).

The likelihood of near-surface permafrost across Alaska, rising from south to north, mapped with Landsat data (Pastick and others, 2015). USGS

Coasts and fisheries

More than 56,000 Alaskans work in the seafood industry, and many thousands more depend on fish for food. Managing fisheries — commercial and Alaska Native alike — means understanding how coasts, rivers, lakes and their ecosystems are changing. Landsat's unmatched archive has helped researchers:

• track the vulnerability of coastlines and subsistence resources around Kotzebue Sound (Gorokhovich and others, 2014);
• model coastal flooding in Cook Inlet (Ezer and Liu, 2010);
• map thermal erosion across thousands of lakes in Noatak National Preserve (Lara and others, 2019).

Fires and floods

For emergency managers, Landsat's free public archive is a cost-effective way to monitor and respond to disasters in Alaska.

Left: the Dalton Highway in northern Alaska during the 2015 floods. Right: a false-color image of the Marr and Little Crazy Mountain Fires of 2019. Landsat, USGS

Landsat for the nation

The USGS National Land Imaging Program supplies satellite imagery and other remotely sensed and geospatial data to government, business, universities and the public, with worldwide access to Landsat data through the USGS Earth Resources Observation and Science (EROS) Center.

• Landsat is the most widely used land remote-sensing source among federal civilian agencies, and local, state, tribal and federal agencies use it to monitor and forecast what happens on the land.
• Its data feed everyday decisions on land, water and resources — protecting life and property, the environment, science and education, climate resilience and the economy.
• Businesses build customer applications on it for logistics, resource allocation and investment; commercial imaging firms use it to refine their products.
• A 2017 USGS study put Landsat's total annual economic benefit to the United States at $2.06 billion, far more than it costs to build and run (Straub and others, 2019).

Landsat 8 and Landsat 9 together image Earth's land every 8 days. NASA and USGS were reviewing a joint study to design the next mission, Landsat Next, to extend what the fact sheet calls the world's longest record of Earth's land surface — a 50-year series. Because the data are consistent, accurate and free, users can study huge areas and long-term trends; like GPS and weather data, Landsat is used every day to understand a changing planet.

Sources

Based on "Alaska and Landsat," U.S. Geological Survey Fact Sheet 2020–3068, U.S. Geological Survey; a work of the United States government in the public domain. Studies cited: Pastick NJ and others, Remote Sensing of Environment 168 (2015) and Global Change Biology 25(3) (2019); Gorokhovich Y, Leiserowitz A, Dugan D, Journal of Coastal Research 30(1) (2014); Ezer T, Liu H, Ocean Dynamics 60(5) (2010); Lara MJ, Chipman ML, Hu FS, Remote Sensing of Environment 221 (2019); Straub CL, Koontz SR, Loomis JB, USGS Open-File Report 2019–1112.