Boris Johnson has warned world leaders that failure to address the issue of climate change will undermine global security.

Chairing a virtual meeting of the United Nations Security Council (UNSC), the Prime Minister said climate change was a “geopolitical issue every bit as much as it is an environmental one”.

He called for action to help vulnerable countries adapt to climate change and cutting global emissions to “net zero” – which requires huge cuts to greenhouse gases and any remaining pollution to be offset through measures such as planting trees – to protect prosperity and security.

“I know there are people around the world who will say this is all kind of green stuff from a bunch of tree-hugging, tofu munchers and not suited to international diplomacy. I couldn’t disagree more profoundly,” he said.

“If this council is going to succeed in maintaining peace and security worldwide, then it has got to galvanise the whole range of UN agencies and organisations into a swift and effective response.”

He added: “When are we going to do something if we don’t act now when changing sea levels are affecting navigation around our coasts or when huddled masses fleeing drought or wildfire or conflict over resources arrive at our borders.

“It is a matter of when, not if, your country and your people will have to deal with the security impacts of climate change.”

The UNSC session is the first leader-level discussion it has held on climate, and is the first time it has been chaired by a British prime minister in nearly 30 years.

It comes as countries increasingly face the effects of rising temperatures and extreme weather, which are forcing populations to move and creating competition over increasingly scarce resources.

In a video message to the meeting, Sir David Attenborough said the UN’s Cop26 climate summit, being hosted by the UK in November in Glasgow, could be the last opportunity to make the necessary changes.

“If we bring emissions down with sufficient vigour we may yet avoid the tipping points that will make runaway climate change unstoppable,” he said.

“In November this year, at Cop26 in Glasgow, we may have our last opportunity to make the necessary step-change.

“If we objectively view climate change and the loss of nature as worldwide security threats – as indeed they are – then we may yet act proportionately and in time.”