The US President is expected to reveal he's pulling out of the Paris Agreement on Thursday.
Speaking to Premier, Ben Niblett from Tearfund said distressing news but people need to keep their focus.
He said: "Don't let Donald Trump put you off. It is really urgent that we tackle climate change for the sake of the poorest people in the world who are being hit by it right now."
He also dismissed suggestions it's not a current problem and one that will only affect our descendants at some time in the decades to come.
"This is not something that is going to happen in the future, if we don't watch out," he said. "It's not something that will affect our grandchildren. It is happening now, ordinary people are going hungry now."
Niblett said he is also remaining positive and each one of us can do something to help:
"We know how to avoid it. There are simple things that people can do right now; to eat less meat, to switch to renewable electricity from a renewable supplier and to fly less.
"Those are just things that ordinary people can do without waiting for governments."
He's also urging people to make it an issue in the general election campaign.
"It's really useful, if you get the chance to speak to your candidates, for them to hear that climate change is something that their voters care about and something that the Church cares about."
Meanwhile, China said it remains committed with its Prime Minister saying that fighting climate change is a "global consensus" and an "international responsibility".
Britain's Foreign secretary Boris Johnson said the UK will continue to lobby the US on climate change and reducing co2 emissions.