An American climate scientist says anybody in the position of influence including the US president cannot do anything about global warming now because it is “irreversible” at this point.

Dr. Guy McPherson, professor emeritus of natural resources - ecology - and evolutionary biology at the University of Arizona, made the remarks in a phone interview with Press TV on Friday.

Donald Trump, the US Republican Party’s presumptive presidential nominee, said on Thursday that he would pull America out of the UN global climate accord if elected, spelling potential doom for a treaty many scientists view as a last chance to limit global warming.

"We're going to cancel the Paris climate agreement," Trump said at the Williston Basin Petroleum Conference in Bismark, Dakota.

The Paris climate agreement, which deals with greenhouse gases emissions mitigation, adaptation and finance starting in the year 2020, was negotiated by representatives of nearly 200 countries in Paris and adopted by consensus on December 12, 2015.

On April 22, 2016, some 177 countries, including the United States, signed the climate treaty at UN headquarters in New York. But it has not entered into force yet.

Dr. McPherson said, “Donald Trump, in his recent statements about climate change and global warming is reflecting the sentiment of many people he is trying to appeal to.”

“There are many people who deny the evidence underlying anthropogenic climate change. And apparently Mr. Trump is one of them,” he added.

“In the long run, I don’t think it will make much difference. We are in the midst of an abrupt climate change. It is irreversible at a time span that matters to humans,” the scientist said.

“So ultimately I don’t think Mr. Trump’s proposals for inaction will make much difference. He is the part of the circus comprising the political theater,” he noted.

“On the other hand my views might be jaded by the fact that I have promoted anarchism for a long time," he pointed out.

"So I don’t believe anybody in the position of influence including the president has the potential to make a lot of difference in terms of national level or international level issues such as this,” the expert concluded.