COUNTRIES have been urged to “stop the assault” on the planet and increase their ambition on cutting the greenhouse gases that drive climate change.

United Nations secretary general Antonio Guterres warned leaders the world was heading for a “catastrophic” 3C of warming, as he urged them to declare a state of climate emergency in their countries until they had become carbon neutral.

They also needed to show action now, with ambitious targets to cut emissions up to 2030, he told a UN climate ambition summit taking place online.

Boris Johnson, co-hosting the event, warned climate change was far more destructive than Covid-19 which has gripped the world this year, but said there was now a surge of scientific optimism, as vaccines started to be rolled out.

“My message to you all is that together we can use scientific advances to protect our entire planet, our biosphere against a challenge far worse, far more destructive than coronavirus,” the Prime Minister told the summit.

A green recovery from Covid-19 could create thousands of jobs, he said, and the world could radically cut dependence on fossil fuels, change agricultural practices and reverse the processes “by which for centuries humanity has been quilting our planet in a toxic tea cosy of greenhouse gases”.

Dozens of world leaders, including Chinese president Xi Jinping, India’s prime minister Narendra Modi, Canadian prime minister Justin Trudeau, Irish Taoiseach Micheal Martin and Yoshihide Suga, prime minister of Japan, are speaking at the event.

So too are European leaders, the Pope, the US governors of Massachusetts and Michigan, finance and business bosses and heads of UN climate, environment and development bodies.

But countries including Brazil and Australia did not secure a speaking slot, amid criticism their plans on emissions are far too weak to protect the climate.

The summit, co-hosted by the UN, UK and France, marks five years since the Paris Agreement – the world’s first comprehensive treaty on tackling climate change – was secured in the French capital.

The Paris Agreement commits countries to take action to limit temperature rises to “well below” 2C (3.6F) above pre-industrial levels and pursue efforts to keep them to 1.5C (2.7F).

Higher temperature rises will lead to increasingly severe impacts including rising seas, more extreme storms, floods, droughts and wildfires, lower crop yields, people displaced from their homes and loss of wildlife.

But countries’ plans for cutting emissions up to 2030, which they have to submit as nationally determined contributions (NDCs) under the Paris Agreement, leave the world on track for more than 3C (5.4F) of warming.

Countries had been due to submit new plans this year ahead of key UN Cop26 talks due to be held in Glasgow, but with the pandemic delaying that until next November, the online summit is being held to maintain momentum on the crisis.

The UK, submitting its first national plan outside of the EU, has committed to cutting its greenhouse gas emissions by at least 68% on 1990 levels by 2030, on the way to reducing pollution to “net zero” by mid-century.

The Prime Minister has also announced the UK will end direct taxpayer support for fossil fuel projects abroad as it seeks to show leadership on climate change ahead of hosting the Cop26 talks.