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Near-surface permafrost in Alaska is in danger of degrading with projected warmer conditions. Detailed information is needed to adequately monitor permafrost, but previous modeling of permafrost properties has typically been done at coarse resolution. A new study, led by the USGS Earth Resources Observation and Science (EROS) Center, developed the first medium-resolution (30-m) map of near-surface (within 1 m) permafrost for all of mainland Alaska.
Researchers used models to project permafrost degradation in the future based on various climate scenarios described in the Intergovernmental Panel on Climate Change (IPCC). Projections indicate that climate impacts (excluding fire impacts) will cause a decrease in near-surface permafrost of 16 to 24 percent by the end of the 21st century. Predictions of permafrost degradation were most pronounced for central Alaska, where permafrost temperatures typically hover around the melting point of 0°C.
The colors on this map indicate the probability that there is near-surface permafrost currently. Red and orange shades are areas with a low probability of permafrost, and blue shades are areas with a high probability of permafrost. When comparing the current map to future scenarios, the expectation of degraded permafrost is evident.
The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and predicting future vegetation and carbon stocks. For more information, see the research article in Remote Sensing of Environment.
Two dams at an iron ore mine in southeastern Brazil broke on November 5, 2015, sending mine waste cascading into nearby valleys. The muddy floodwaters destroyed hundreds of homes in the village of Bento Rodrigues, which lies in a valley below the mining area. Natural color images from Landsat 8 compare how the area looked before the breach in the dams to how it looked one week after the incident.
The orange colors along the left side of the images are open pit iron ore mines. The dams burst from the tailings ponds, which hold mine waste. The November 12 image shows the orange sediment flowing down a valley through the dark green rain forest. This sediment may contain mining chemicals that could affect the fertility of downstream farmland. Researchers are still testing the water to get a better idea about the contents of the mine waste.
Death Valley 1,000-year Flood Event October 29, 2015
This October, a system of storms caused significant flooding in most of Death Valley National Park, California. Collectively, the area only received 1–2 inches (2.5–5 centimeters) of rain, but the annual average in Death Valley is about 2 inches (5 centimeters). The largest of the storms occurred on October 18. Flash floods from the storm destroyed roads and utilities, and damaged several historical structures. This was the largest flood event in the recorded history of the area.
In this image pair Landsat 8 images contrast October 2014 (a year with typical precipitation) to October 2015. The false color images highlight hydrogeology; the areas in green to blue are the locations with moisture content. Especially striking is the Badwater Basin, normally a dry lake bed. In the 2015 image, it is full of water.
Landsat imagery acquired before and after the flood event will help with monitoring and evaluation of landscape response and impacts.
Landsat 7, which launched on April 15, 1999, has been continuing to acquire land images worldwide for 16 years. Landsat 5 may hold the Guinness World Record for longest Earth-observing satellite at 28+ years, but Landsat 7 also has an impressive track record. In fact, Landsat 7 has now acquired over 2 million images. They are all freely available online at USGS GloVis or EarthExplorer.
Landsat 7 and Landsat 8 acquire over 1,200 new images per day. This is more data than at any other time in the history of the Landsat program.
The 2 millionth Landsat 7 scene includes a portion of northwestern Madagascar, acquired on September 11, 2015. The dark region in the lower left is the Ankarafantsika Natu