If atmospheric rivers over Antarctica double, there would be enormous consequences to the planet. Photo: Unsplash
As the Earth’s climate changes, we can expect to see significant impacts to our way of life. It’s not really an if anymore, which is pretty depressing, but humans are resilient if nothing else. One of those significant impacts is an increase in atmospheric rivers, which dump huge amounts of precipitation onto whatever area they happen to be flowing above. A new study published in the journal Nature predicts that atmospheric rivers over Antarctica could double by the year 2100.
According the National Oceanic and Atmospheric Administration, an atmospheric river is a relatively long and narrow “river” of water vapor in the sky above the ocean. Aside from places like the tropics, atmospheric rivers are the main driver of how water vapor moves around our planet. The amount of water in a big one is pretty staggering: it’s comparable to 7.5 to 15 times the flow at the mouth of the Mississippi River. When they hit land, that precipitation is released as heavy rain or snow.
As our planet heats up due to greenhouse gasses, more water is evaporating. That means more water in our atmosphere, which means more powerful and numerous atmospheric rivers. While you likely don’t live in Antarctica, these things have global effects that, if the prediction comes to fruition, will change the climate — and by extension the weather — of our planet.
“The Antarctic Ice Sheet plays a key role in our climate system by modulating present and future global mean sea level through the accumulation, storage, and discharge of ice over time,” the authors of the study wrote. “In the last four decades, mass loss from Antarctica has increased by a factor of six, driven by ice shelf basal melting and resultant grounding line retreat in West Antarctica, leading to an acceleration of ice discharge into the ocean. Future simulations for Antarctic mass balance project losses of up to 150 cm sea level equivalent per year by 2100.”
Atmospheric rivers over Antarctica are a little more sensitive to the increasing levels of moisture in the atmosphere, so researchers decided to plug a bunch of data into a simulation to find out what a future would look like should we continue down the path we’re on. That path isn’t one of strong efforts to reduce emissions, since we’re not really doing that now and it doesn’t seem too hopeful that we will.
When the results came in, the scientists found something they likely expected, but something alarming nonetheless.
“An exponential increase in atmospheric moisture occurs over the Southern Ocean and Antarctica over the twenty-first century relative to the present-day, strengthening the pole–equator moisture gradient,” they said. “The result of the increase, the simulation predicted, could be that the frequency of atmospheric rivers over Antarctica doubles by the end of the century, with the precipitation that these events bring increasing by 2.5 times between 2066 and 2100.”
It’s super important that scientists have a grasp on what we can expect in Antarctica in the coming years, because the sparsely populated area is extraordinarily important when it comes to the rest of the planet. More than half of the fresh water in the world is in the Antarctic Ice Sheet, and if all of it were to melt, the global sea level would rise over 200 feet. While that’s not likely to happen any time in the near future, even a fraction of that amount of melting would be pretty catastrophic.
“Because atmospheric rivers deliver massive precipitation to Antarctica and significantly impact snowfall variability, understanding their future patterns is crucial to projecting Antarctica’s contribution to sea level rise,” said study author Michelle Maclennan, in a statement. Maclennan works as a climate scientist at the British Antarctic Survey.
It’s worth noting that the team found that most of the precipitation that would fall in the predicted scenario would fall as snow, which would significantly slow the sea level rise, but even with that taken into account, a doubling of atmospheric rivers over Antarctica would have enormous consequences to the planet we call home.
