The satellite reveals that the Arctic is melting at an “alarming rate” due to excessive heat produced by human emissions of greenhouse gases.
Multi-year sea ice in the Arctic was about 50 centimeters (1.6 feet) thinner in 2021 than it was in 2019, a reduction of about 16% in just three years. It is replaced by less permanent seasonal sea ice that totally melts each summer.
Over the past 18 years, winter sea ice in the Arctic Ocean has lost a third of its volume – a staggering figure that may have been underestimated in the past, according to research. This is the first study to use years of satellite data to estimate both ice thickness and snow depth at the summit.
“Arctic snow depth and sea ice thickness and volume are three very difficult measurements to obtain,” says polar scientist Ron Kwok of the University of Washington.
The data comes from the ICESat-2 and CryoSat-2 radar satellites orbiting the Earth.
“The main finding for me is the remarkable loss of Arctic sea ice volume in winter – a third of the volume of winter ice lost in just 18 years – which has accompanied a widely reported loss of old and thick Arctic sea ice and a end-of-ice extent decline in summer.
What makes the study significant is how it combines LiDAR technology from ICESat-2, launched three years ago, and radar technology from CryoSat-2. While LiDAR uses laser pulses and radar uses radio waves, they both detect objects (in this case, snow and ice) based on the reflections returned to them.
Without this data, it’s hard to judge the thickness of the ice, because of how snow can weigh the ice down and change the way it floats in the ocean. Using climate records to estimate snow depth in the past, scientists overestimated sea ice thickness by up to 20 percent or 20 centimeters (0.7 feet), according to the study.
Multi-year ice is known to be thicker and therefore more resistant to melting than seasonal ice – you can think of it as a kind of reservoir for the Arctic. As it depletes and is replaced by seasonal ice, the overall thickness and volume of Arctic sea ice is also expected to decrease rapidly.
“We didn’t really expect to see this decline, because the ice would be much thinner in just three years,” says polar scientist Sahra Kacimi, from the Jet Propulsion Laboratory at the California Institute of Technology. Combining previous records from the old ICESat satellite to look back over 18 years, the researchers estimate that around 6,000 cubic kilometers (1,439 cubic miles) of winter ice volume was lost during that time.
That the past three years have seen a sharp decline is also concerning. Less ice means massive disruption of ecosystems. This could eventually alter the essential ocean currents we all rely on, and most likely also accelerate the climate change happening all around us. Reducing our fossil fuel emissions is the only way to stop this and we can all still play a more powerful role than we probably realize. Even our perceptions can make a difference.
Meanwhile, it’s promising that the new ICESat-2 satellite, launched in 2018, is performing as expected, and we’re getting more data on Arctic ice levels than ever before – even if it makes for a grim reading. “Current models predict that by mid-century we can expect ice-free summers in the Arctic, when older ice, thick enough to survive the melt season, will be gone,” says Kacimi. .
Summary of news:
- Satellites reveal Arctic ice is already thinning at a ‘frightening rate’
- Check out all the news and articles from the latest space news updates.