In contrast to the leaders of six other world leaders at a G7 summit in Italy, the US President (pictured above with the Canadian PM Justin Trudeau, French President Emmanuel Macron and President of the European Council Donald Tusk) said he would decide next week on whether to support the Paris Agreement.
Tearfund's Head of Advocacy, Paul Cook, said: "While Tearfund welcomes the continued strong commitment from six of the Heads of State, to tackle climate change, we are disappointed that the United States could not reach a consensus.
"It is unfortunate that the US Government is not yet convinced of the great economic benefits clean energy can provide.
"The global momentum to respond to this generation's challenge to ensure economic growth while protecting people and places affected by climate change will continue regardless, but we hope it does so with the support and leadership of the US."
The pledge, which was accepted last year by then-US President Barack Obama, commits signatories to keep global warming below two degrees Celsius.
Consensus crumbles at #G7summit at the expense of the world's poorest people https://t.co/6Gn9PIIpqg
— Oxfam International (@Oxfam) May 27, 2017
A final communique released at the summit in Sicily said the UK, Germany, France, Italy, Canada and Japan had voiced a "strong commitment"; however, the US was "not in a position to join the consensus on these topics".
Paul Cook from Tearfund added: "This is a disappointing statement on climate change that does not go far enough in outlining how the G7 plans to meet the agreement to keep global warming well below 2°C made in Paris to tackle climate change.
"The world's poorest, who least deserve it, are hit hard by the life and death impacts of a changing climate, unstable seasons and a natural world out of balance.
"We urgently need action to restore the balance for a more stable, cleaner and healthier world. World leaders should recognise that it is a global threat to economic security, livelihoods and agriculture."
German Chancellor Angela Merkel told reporters on the Italian island "the entire discussion about climate was very difficult, if not to say very unsatisfying", while Italian Prime Minister Paolo Gentiloni, said: "I hope they [the US] decide in the right way."