Au Revoir, Paris Climate Accord. Hello, Apocalypse?

President Donald Trump's decision to withdraw the U.S. from the Paris Agreement has sparked outrage and concern. CUNY Chancellor James B. Milliken joined hundreds of leaders in signing the 'We Are Still In' open letter, which pledges continued support for the Paris Agreement.

Others are turning to the press, social media, and the arts to protest the pullout. Concern has even sparked interest in a new film genre: climate fiction.
 
One such film, two°C, portrays New York City landmarks engulfed by rising rivers in some not-too-distant future when the average global temperature is up by two degrees Celsius. (Watch at 2:57 of the film and you'll see an eerily familiar sight.)
 
How likely is this apocalyptic scenario? How worried should we be about climate change?
 
We turned to Professor Athanasios Koutavas (GC/College of Staten Island, Earth and Environmental Sciences) and Professor Stephen Pekar (GC/Queens College, Earth and Environmental Sciences), who study aspects of human-induced climate change, for answers.*
 
Will New York City be largely submerged and uninhabitable in the next century?
 
Koutavas: These types of scenarios are on the upper end of projections for sea-level rise and so, while not impossible, are not very likely. They invoke sea-level rises of about 15 feet in response to two degrees Celsius of warming by 2100 or so. While the warming may very well happen, it would take a long time for the large glaciers to melt and sea level to rise this much."

Pekar: It is extremely likely that average temperatures in New York City will rise by two degrees Celsius in the coming century . . . The main concern is that sea level will rise by at least five to six feet. This will flood significant portions of lower Brooklyn, Queens, Staten Island, and Manhattan. The result will be the loss of billions of dollars of real estate properties and the displacement of hundreds of thousands of New Yorkers.
 
What are the implications of our withdrawal from the Paris Agreement?

Koutavas: I see the implications as being mostly political, but relatively minor for carbon emissions and climate. The Paris accord is a serious effort to develop mechanisms of international cooperation to manage the climate problem. The U.S. would be better served to stay in it and try to influence and shape the global effort. But U.S. carbon emissions are only 14 percent of global emissions, and U.S. emissions are already falling in absolute terms because of technological innovations and expansion of natural gas and renewables. So the U.S. trend is in the right direction-downward. It is happening independently of Paris commitments (though less fast) and will likely continue.

Pekar: One of the most humiliating events to befall the U.S. in recent years has been Trump's decision to pull out of the Paris climate accord, which placed the U.S. in a notorious group of only two other countries: Syria and Nicaragua. Withdrawing from the Paris climate agreement will be damaging to our country both politically and economically.

What have you found in your research?

Koutavas: Weather changes are a very real concern, but it is a difficult proposition to separate natural changes in weather patterns from those caused by human factors. That's because much of the earth's weather is tied to ocean circulation patterns (for example El Niño) and these are tied to natural oscillations in the ocean that are not very predictable. These ocean oscillations are still a frontier in our understanding of global climate and weather. As far as my own work goes, studying the patterns of El Niño over long timescales, I don't see evidence of any changes happening presently that are unusual.

Pekar: In my research, at geologic timescales, the size of the Antarctic ice sheet has fluctuated by up to 60 percent of its total volume resulting in sea-level changes of well over 100 feet. While this took centuries to a millennium to occur, we only need a small percentage of that to cause a catastrophe of flooded cities that would result in hundreds of millions of refugees.
 
My studies show that during times when atmospheric carbon dioxide was as high as what is expected during this century, the Antarctic ice sheet size varied greatly, resulting in sea-level changes of over 100 feet. While this would not happen anytime soon, if the ice sheet size varied by just 10 percent of this, we would see a 10-foot sea-level rise.

Learn more about Koutavas' research in paleoclimatology, paleoceanography, and paleoecology.
 
Learn more about Pekar's geology research, which has led him to the tropics and Antarctica.
 
*Responses were edited for space and clarity.