The Arctic will be ice-free within a decade during the summer months. A new study from the University of Colorado Boulder says the Arctic could become ice-free in August or September as early as the 2020s or 2030s. The Arctic could then remain ice-free for nine months of the year, as predicted by worst-case climate scenarios. This is largely due to the fact that sea ice, which reflects solar radiation, melts into the open ocean, which absorbs solar radiation.
Warming in the Arctic
Nowhere is climate change felt more acutely than in the Arctic. Over the past four decades, the world’s icy summit has warmed about four times faster than the rest of the planet. This means that temperatures in the Arctic have risen more than 3 degrees Celsius since the early 1980s, and this big jump in temperatures is largely due to sea ice, or lack thereof. Ice typically acts as a reflective coating, reflecting approximately 85 percent of solar radiation back into space. When this ice turns into open ocean instead, it absorbs 90 percent of solar radiation rather than reflecting it, creating a feedback effect of increased warming.
For many years, scientists believed that the ice-free Arctic during the summer months, around August or September, was inevitable and would likely occur sometime in the 2040s. But recently, scientists are reconsidering this assessment. In the summer of 2023, the warmest year on record, an international team of researchers published a paper suggesting that Arctic sea ice could disappear a full decade earlier than previously thought. An “ice-free” Arctic does not mean that the polar region will become completely ice-free, as the name suggests. We are talking about ice covering 1 million square kilometers (386,000 square miles).
Significant reductions in Arctic ice will cause warming oceans, rising sea levels that will threaten coastal communities around the world. In addition, sea ice plays an important role in moderating ocean waves and reducing coastal erosion, which poses problems for coastal cities and island nations. Increasing ocean temperatures could also lead to non-native fish expanding into Arctic waters, likely wreaking havoc on these already fragile ecosystems.
“Even if ice-free conditions are inevitable, we still need to keep our emissions as low as possible to avoid prolonged ice absence,” the researchers said in a press statement. “Unlike the Greenland ice sheet, which took thousands of years to build, even if we melted all the Arctic sea ice, if we could then figure out how to take CO2 back out of the atmosphere in the future to reverse the warming and the sea ice would return to place in ten years.”
Cracks in Antarctica’s glaciers
Researchers at the University of Washington have demonstrated the fastest known large-scale ruptures along the Antarctic ice shelf. A study recently published in AGU Advances shows that a crack about 10.5 km long formed in 2012 on the Pine Island Glacier – a retreating ice shelf that holds back the larger West Antarctic Ice Sheet – in about 5.5 minutes. This means that the crack appeared at a speed of approximately 35 m/s, or about 126 km/h.
The study shows that under certain circumstances, an ice shelf can collapse at a very high rate. Satellite images were used as input data for the study, as well as data from three seismic instruments installed on the ice shelf by other researchers in 2012. According to the team, the rift is a crack that cuts through about 300 meters of floating ice. Such cracks are a precursor to melting of the ice shelf, in which large chunks of ice break off from the glacier and fall into the sea.
In other parts of Antarctica, cracks often develop over months or even years, but this can happen more quickly in a rapidly changing climate, and what’s happening at Pine Island Glacier suggests the West Antarctic Ice Sheet may have already passed the tipping point of collapsing into the ocean.
Greenland
A study published last month in the journal Nature effectively documents ice loss at the edges of glaciers where they meet the sea. The researchers manually recorded changes at the edges of the ice and also trained algorithms to track melting along the boundary where the glacier meets the sea. Previous studies have focused primarily on recording melt in a fixed ice mask, a fixed perimeter of the ice sheet, often missing the noticeable effects of ice breaking off from the edges of the ice sheet. A new study shows that 1,000 gigatons of ice remained unaccounted for in previous estimates.
Because the lowest edges of the ice sheet are submerged, previously undetected ice loss did not directly contribute to sea level rise. However, a thinning ice sheet could speed up further melting and allow ice currently on land to slide into the water, causing sea levels to rise.
The researchers studied 207 glaciers using 236,328 satellite observations collected from 1985 to 2022, some collected by hand and some collected by artificial intelligence, to look at the melting of the ice along its perimeter. This approach addresses the limitations of previous methods for measuring ice loss in Greenland, which had problems in capturing changes in ice edges due to the fixed perimeters studied.
When ice sheets lose mass, they lose some of their gravitational pull, but the GRACE satellites have difficulty measuring these changes in the narrow, deep fjords through which Greenland’s ice flows, explained Chad Green, lead author of the study, a glaciologist and remote sensing specialist at JLWH. NASA movements. The ice in these fjords is often already below sea level, so when it is lost, it is immediately replaced by seawater, without changing the gravitational pull.
New instruments show that more ice has melted than previously thought, Green and his team found in their recent study. While the loss has minimal direct impact on sea level rise, they say, adding more than 1,000 gigatons of fresh water to the North Atlantic Ocean could change the water’s buoyancy, which could strengthen Greenland’s coastal currents and change the course of future interactions between ice and ocean. Melting icebergs release large amounts of fresh water into the fjords, which can affect the flow of heat in the ocean.