These impressive satellite images show the effects of climate change on Earth – Edition du soir Ouest-France

By Nicolas HASSON-FAURE

For half a century, the satellites of the US Landsat program have relentlessly photographed the Earth’s surface. Their images show a changing planet experiencing drought or retreating glaciers under the influence of climate change. Zoom in on these phenomena, seen from space.

The huge dark colored spot has lost much of its surface. The water in Lake Mead, the largest water reservoir in the United States, is slowly being siphoned away by dry, sandy-colored land. The artificial lake is inexorably drying up, as shown by two images taken in 2000 and then in 2021 by satellites from the US Landsat program that started 50 years ago. The first of these eight spacecraft to be launched into orbit was launched on July 23, 1972. For half a century, they have relentlessly photographed the Earth’s surface, causing them to pose “an unbiased look at climate change”, states the United States Geological Survey (USGS), which manages this program with NASA, the US space agency. Drought, receding glaciers… Satellite observations show a changing planet, affected by climate change. Here are three illustrations, seen from space.

1. The melting of glaciers

A satellite view of the Tibetan Plateau, taken on October 12, 1987. (Photo: Landsat Image Gallery / Public domain)

The same Tibetan plateau as seen from space, 9 October 2021. (Photo: Landsat Image Gallery / Public domain)

Located in the mountains and straddling several Asian countries, the Tibetan Plateau is nicknamed “the third pole” because it concentrates the largest reserves of fresh water outside the North and South Poles, according to the USGS. The region’s blue gold is especially found in “ten thousand glaciers” that characterize this vast territory.

Problem: They are inexorably retreating under the influence of rising temperatures, as evidenced by images taken by American satellites in 1987 and then in 2021. In 34 years, the ice cover has decreased sharply, a phenomenon that is also visible in video on this animation made by NASA:

The glaciers of the Tibetan Plateau are not the only ones retreating in the world. And other satellite images prove it, like these images of the Columbia Glacier in Alaska, taken in 1986 and then in 2014. One clarification: these are not the real colors, the photographs have been recolored to highlight the phenomenon.

Columbia Glacier in 1986. (Photo: Landsat Image Gallery / Public Domain)

The glacier in 2014. (Photo: Landsat Image Gallery / Public domain)

2. Dry

The drying up of Lake Mead, between August 2000 and August 2021. (Photo: Landsat Image Gallery / Public domain)

Other images taken by satellites show what Lake Mead in the American West looks like from space. The images highlight the inexorable drying up of the United States’ Great Reservoir Plan, located in Nevada: at the end of July, the water level was at its lowest since 1937, and the filling of the artificial lake, then indicated the daily US New York Times . It was then filled to 27% of its capacity!

Also read: United States. ‘It’s beyond the drought’: Lakes Mead and Powell turn into ‘dead pools’

This trend is explained by the “mega-drought” that has affected southwestern North America for 22 years: it is the most important ever known since the year 800, that is, more than 1,200 years, indicated a study published in the journal Nature climate change February last year.

The name Lake Mead has been in the international media in recent weeks: Here, the receding waters have revealed human bones that could belong to people who were killed by the underworld decades ago and whose bodies had been thrown into the lake so that they would never be found.

3. Destructive storms

A photo of part of the Texas coast before Hurricane Harvey hit on Aug. 25, 2017. (Photo: USGS EROS/Public domain)

The same region after the passage of the hurricane, September 5, 2017. (Photo: USGS EROS / Public domain)

Satellite camera lenses also captured images of devastation, such as the massive flooding caused by Hurricane Harvey in Texas, the southern United States, in 2017. The storm killed at least 68 people in that state alone (it also affected other regions of the country), according to to the United States Agency for Oceanic and Atmospheric Observation (National Oceanic and Atmospheric Administration, NOAA). As for the material damages, they were estimated at 125 billion dollars, or more than 122 billion euros.

Anyway, “it is difficult, if not impossible, to assess the impact of global warming caused by human activities on any given storm”, says the USGS. But this climate change has increased the amount and intensity of the heavy rainfall that the hurricane brought, according to several scientific studies published in 2017 and cited by the Science Daily website.

Climate change has an effect on the intensity of these meteorological phenomena. “The fuel of cyclones is the temperatures observed on the surface of the oceans. The higher these temperatures are, the more energy there is in the hurricane system, explained Fabrice Chauvin, climatologist at the National Center for Meteorological Research in 2021 to Western France. It is not every cyclone that gets stronger, it is the proportion of large cyclones that gets bigger. »

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