“The results of this study are [the] “If global temperatures rise by more than 1.5 degrees Celsius above pre-industrial levels and this warming persists, the West Antarctic ice sheet will become unstable and collapse,” Tim Naish, co-author of the new study, said in an email. Stated.
“The world is on track to reach the 1.5C temperature target over the next five years,” added Naish, a paleoclimatologist at Victoria University of Wellington in New Zealand. “We are dangerously close” to a collapse of the Antarctic ice sheet that could cause today’s global sea levels to rise by up to 4 meters over the next few centuries.
The West Antarctic ice sheet has collapsed many times during past warm periods in Earth’s history. Some records indicate that the ice sheet collapsed at some point in the past million years, but scientists lacked evidence to pinpoint that time more precisely. Now the octopus becomes their watch.
Tarkett’s octopus may not be the continent’s most charismatic animal, but this tiny ocean-floor creature has inhabited the region for millions of years. Although individuals only live a few years, their DNA is a time capsule of the lives of their ancestors.
Similar to the 23andMe test used in humans, the researchers analyzed the genetic material of nearly 100 Southern Ocean octopuses stored in museums and for research purposes. Some of the samples were decades old and had deteriorated, but new gene sequencing techniques allowed the team to analyze genomic data at higher resolution than ever before.
The results were amazing. Octopuses are located thousands of miles around the continent. Weddell Sea, Amundsen Sea, Ross Sea — were genetically similar. Currently, ice sheets physically separate these oceans. Given that Antarctic octopuses don’t travel much, it’s unlikely that Antarctic octopuses ever traveled the continent. So how did this species diverge so far?
Test past human migration patterns using the same type of model, The team simulated various scenarios to uncover the octopus’ historic voyages. They ran hundreds of thousands of variations under scenarios where the ice sheet was completely intact, partially collapsed, and completely collapsed.
One route stood out. After the western ice sheets completely melted, octopuses migrated directly between oceans, creating gaps in the rocks between regions.
The octopus “found a way” [in the sea] “They migrate over many generations,” said Sally Lau, lead author of the study and a biologist at James Cook University. “As they migrate, they interbreed with each other, [genes flow] from one group to another. ”
According to research models, this genetic exchange occurred during the most recent warm period, about 129,000 to 116,000 years ago, known as the Last Interglacial. During the last interglacial, average global temperatures were 0.5 to 1.5 degrees Celsius above pre-industrial levels. Global sea levels were 5 to 10 meters higher than they are today, and Naish said snowmelt from Antarctica probably contributed significantly.
Scientists are concerned that the last interglacial could be an indicator of what’s to come on Earth today. Current global temperatures are already about 1.2 degrees Celsius higher than the pre-industrial average.
Tina van de Vryld, a paleoclimate researcher at Imperial College London, said: “If we maintain the level of warming we are currently experiencing, sea levels will eventually be similar to those seen in the last interglacial period. I am confident that we will reach that level.” She was not involved in the research. She said: “What we don’t know is how quickly this will happen.”
Sea level is already predicted to be increase 30cm But van de Vryld said that if the West Antarctic ice sheet were to collapse with 1.5 or 2 degrees of warming, as research suggests, the uplift could reach 1 or 2 meters. He said there is.
At current temperatures, parts of the West Antarctic ice sheet may already have reached the tipping point of melting. Ice in the Amundsen Sea, where Thwaites’ “terminal” glacier is located, already shows irreversible vulnerability to melting. One saving grace is that parts of the ice sheet near the Ross Sea are unlikely to melt for now, Van de Vryld said.
“Ice sheets are beginning to melt in both the Ross Sea and Amundsen Sea regions, which means a complete collapse of the West Antarctic Ice Sheet,” she said.
Van de Vlield said the study was “interesting” and was surprised by the authors’ confidence in narrowing the time period to 125,000 years ago. The results are also timely, as van de Frierd and his colleagues are currently drilling through the western Antarctic ice sheet to find direct geological evidence of when the ice sheet collapsed. That’s what I got. Although the approach is different, the purpose of the new study is similar.
An international project named SWAIS2C, drilling to find old sediments deposited beneath the ice. Ice cores record the composition and temperature of the atmosphere at the time, providing clues to what was happening on Earth.
“The geological past provides a window into a future world that could be 1, 2, 3 or even 4 degrees warmer,” said SWAIS2C co-principal scientist Huang Mr. de Frierd said. SWAIS2C is designed to study the vulnerability of the West Antarctic ice sheet in the event of warming of up to 2°C.
“There is no such thing as a perfect geological analogue for the experiments we are currently conducting on Earth,” she says. “But the best way to understand how the Earth will respond to unprecedented greenhouse gas emissions is by knowing its geological past.”