Due to the excess heat created by human greenhouse gas emissions, new satellite data has shown the Arctic is melting at a "frightening rate."
According to the data, end-of-season Arctic multiyear sea ice - ice that lasts for several years - was around 50 centimeters (1.6 feet) thinner in 2021 than it was in 2019, a reduction of around 16% in just three years. It is being replaced by less permanent seasonal sea ice, which melts completely each summer.
The study revealed that the Arctic Ocean's winter sea ice has lost one-third of its volume over the last 18 years, a stunning amount that may have been underestimated previously. It's the first research to use years of satellite data to determine ice thickness as well as snow depth on top.
"Arctic snow depth, sea ice thickness, and volume are three very challenging measurements to obtain," polar scientist Ron Kwok, from the University of Washington, said.
"The key takeaway for me is the remarkable loss of Arctic winter sea ice volume - one-third of the winter ice volume lost over just 18 years - that accompanied a widely reported loss of old, thick Arctic sea ice and decline in end-of-summer ice extent."
The data comes from the Earth-orbiting satellites ICESat-2 and radar CryoSat-2.
The study's significance stems from the way it combines ICESat-2's LiDAR technology and CryoSat-2's radar technology, which was launched three years ago. While LiDAR employs laser pulses and radar employs radio waves, both identify objects (in this case, snow and ice) based on reflections returned to them.
Without this data, estimating ice thickness is difficult due to the way snow may weigh down ice and modify how it floats in the water. According to the study, scientists have overestimated sea ice thickness by up to 20% or 20 centimeters (0.7 feet) in the past by utilizing climatic records to predict snow depth.
Multiyear ice is believed to be thicker and thus more resistant to melting than seasonal ice - think of it as a reserve for the Arctic.
The overall thickness and amount of Arctic sea ice are predicted to rapidly decline as it depletes and is replaced by seasonal ice.
We can only stop this by reducing our fossil fuel emissions, and we can all play a bigger part than we probably know. Even our own opinions might have an impact.
Meanwhile, the newer ICESat-2 satellite, which was deployed in 2018, appears to be functioning properly, and we're collecting more data about Arctic ice levels than ever before - even if it makes for depressing reading.
The research has been published in Geophysical Research Letters.