Representatives from nearly 200 countries gathered in Madrid for the start of a two week conference aimed at tackling climate change on Monday.
UN Secretary General Antonio Guterres has warned that efforts to reduce carbon emissions are "utterly inadequate", and global warming could pass "the point of no return".
Andy Lester from conservation organisation A Rocha UK told Premier Guterres' comments are the "understatement of the year".
"The reality is climate change is running away from us in an alarming rate. And the best efforts so far have been woefully inadequate," he said.
"We're going to have to do so much more if we're going to contain what is turning into a serious global crisis of proportions that we have not seen before."
Lester says it is essential for all governments to "toe the line" and unite in tackling the issue for any significant change to be made.
"It's about applying pressure to those governments who don't think climate change is worth taking seriously. Brazil, Australia, United States, India, amongst others"
He added: "Unless we stick together on this, we're not going to see any significant movement."
The summit, which moved from Chile following anti-government protests, aims to establish an international strategy to cut greenhouse gases and address the climate crisis.
Lester is not optimistic effective change will be enforced, saying: "Off the back of Madrid, we're going to hear lots of good things happening, but it's going to be nowhere near on the scale that's needed.
"It requires an enormous effort from those governments who are completely behind the spirit of climate change."
A Rocha is calling on Christians to take drastic action "irrespective of what the governments are doing" to reduce emissions.
"This is going to mean eating less meat, travelling by car far less frequently and going on holidays in the UK rather than going abroad."
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