The Paris Agreement is an understanding between over 100 countries across the globe aimed at keeping global warming in check by cutting greenhouse gas emissions.

"The Paris Agreement's central aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below two degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius," says the United Nations.

The agreement went into force earlier this month and has been ratified by 113 different parties thus far. The United States is one of those parties. However, during the recent US election proceedings, president-elect Donald Trump repeatedly said that he would pull his country out of the accord and remove restrictions on energy production in America.

Wondering just what impact that could have on the climate and the agreement itself, as part of our regular column called "One Big Question," we turned to Donald Boesch, professor of marine science and president of the University of Maryland Center for Environmental Science, to see what he thought. Here's what he had to say.

If the Trump Administration withdraws from the Paris Agreement or fails to reduce its emission by the amount and timing of its commitment, it will likely be impossible to limit global warming below two degrees Celsius, even if all the other nations succeed in achieving their commitments. I don't know if this scenario has been modeled, but it seems to me that global temperature would be likely to warm by three to four degrees Celsius. The consequences of this would mean for a place like Australia, an extra 0.3 m of sea level rise during this century, even more droughts and heat waves, and an existential crisis for the Great Barrier Reef.

The U.S. is presently responsible for 20 percent of global emissions, but, because it is such large emitter on a per capita basis, must bear a larger percentage of the needed reductions over the next 30 years. Furthermore, without the participation of the US, it seems to me to be unlikely that all other nations would be obliged to honor their greenhouse gas reduction commitments.

Having said all of this, there are extensive efforts to reduce emissions at the state level (e.g. California and Maryland) and among global businesses with a large presence in the US such that US emissions would likely still be reduced. However, the US commitments depend heavily on what is called the Clean Power Plan implemented by executive action under the Obama Administration. This requires reductions in carbon dioxide emissions from electrical generation, so the states will also have difficulty in achieving their emission reduction goals as this is regulated at the federal level.

Boesch also pointed us to an interview he did with public radio station WYPR earlier this month in which he said the following.

To misunderstand the breadth of support (the Paris Agreement has) across the globe is a real danger for our country. It spills over not only in terms of the economic markets that are going to drive the future, in that we'll be left out of them, but we'll be a pariah. We'll be a pariah in the global stage on almost everything if we stay out of this. This is that serious.