New study looks far into the climate future
FRISCO — Using the rest of Earth’s fossil fuels is not an option — at least not if humankind wants to avoid 150 to 200 feet of sea level rise, a team of prominent scientists said after trying to project the fate of the world’s ice sheets over the next 10,000 years.
Burning the remaining stores of coal and oil would likely lead to a complete meltdown of Antarctica, which would, over the course of millenia, swamp most of the planets densely populated areas, and them some.
“Our findings show that if we do not want to melt Antarctica, we can’t keep taking fossil fuel carbon out of the ground and just dumping it into the atmosphere as CO2 like we’ve been doing,” said Carnegie Institution researcher Ken Caldeira. “Most previous studies of Antarctic have focused on loss of the West Antarctic Ice Sheet. Our study demonstrates that burning coal, oil, and gas also risks loss of the much larger East Antarctic Ice Sheet.”
The study, published in Science Advances, shows that such a meltdown would inundate areas where more than 1 billion people now live, including New York and Washington, D.C.
Antarctica has already begun to lose ice, and a complex array of factors will determine how fast and how much it melts in the years ahead. Those factors include greenhouse gas-caused atmospheric warming, additional oceanic warming perpetuated by the atmospheric warming, and the possible counteracting effects of additional snowfall.
“It is much easier to predict that an ice cube in a warming room is going to melt eventually than it is to say precisely how quickly it will vanish,” Winkelmann said, explaining all the contributing factors for which the team’s models had to account.
The found that the West Antarctic ice sheet becomes unstable if carbon emissions continue at current levels for 60 to 80 years, representing only 6 to 8 percent of the 10,000 billion tons of carbon that could be released if we use all accessible fossil fuels.
“The West Antarctic ice sheet may already have tipped into a state of unstoppable ice loss, whether as a result of human activity or not. But if we want to pass on cities like Tokyo, Hong Kong, Shanghai, Calcutta, Hamburg and New York as our future heritage, we need to avoid a tipping in East Antarctica,” said co-author Anders Levermann, with thePostdam Institute for Climate Impact Research.
The study also affirmed the global goal of limiting warming to 2 degrees Celsius, finding that, if that target is met, sea level will only rise a few meters and remain manageable. But greater warming could reshape the East and West ice sheets irreparably, with every additional tenth of a degree increasing the risk of total and irreversible Antarctic ice loss.
This is the first study to model the effects of unrestrained fossil-fuel burning on the entirety of the Antarctic ice sheet. The study does not predict greatly increased rates of ice loss for this century, but found that average rates of sea level rise over the next 1,000 years could be about 3 centimeters per year (more than 1 inch per year) leading to about 30 m (100 feet) of sea level rise by the end of this millennium. Over several thousand years, total sea level rise from all sources could reach up to 60 meters (200 feet).