Why satellites are critical to fighting climate change

Why satellites are critical to fighting climate change

Orbiting at breakneck speeds hundreds of kilometers above us, satellites observe both poles almost in their entirety. By frequently revisiting the same locations as they circle the Earth, satellites are our only means of routinely monitoring regional and continental-scale changes in ice cover.

Earth observation satellites continuously image ice from above in various bands of the electromagnetic spectrum. These include visible frequencies, where they operate much like a camera, and microwave frequencies, which see through clouds and the long, dark polar winter.

Since the 1970s, satellite imagery has mapped changes in the structure and extent of glaciers and the colossal Antarctic ice shelves, formed as ice flows off the Antarctic continent to float on the ocean. As ice flows slowly downhill – much like a blob of treacle – satellites can track distinctive features such as crevasses as they move, and measure the speed of the ice.

Satellites such as CryoSat-2 (pictured), which I use extensively in my research and was launched in 2010 by the European Space Agency, map changes in the shape of ice with centimeter-level precision. They work by timing how long it takes for a pulse of electromagnetic radiation to reflect from the Earth’s surface and travel back to the satellite.

By combining data from various satellites and monitoring how ice speed and shape evolves over time, scientists can keep track of how Earth’s ice is responding to its changing environment.

Satellites have completely transformed our understanding since they began to systematically and comprehensively observe Earth’s ice in the 1990s.

They have revealed that the Antarctic and Greenland ice sheets are now losing more ice through melting than can be replenished through snowfall. At the beginning of this period, it was thought that Antarctica and Greenland would be innocent bystanders, taking hundreds of years to respond to changes in global temperatures.

Instead, satellite observations have shown that the ice sheets are responding to climate change within just my lifetime. Antarctica and Greenland are now losing ice six times faster than they were in the 1990s. Antarctica is being weakened from beneath by warmer ocean waters, while Greenland’s ice is melting more in the summer as the atmosphere warms.

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