More than 70 world leaders from across government, business and civil society set out their commitments to tackle climate change at the Climate Ambition Summit 2020 on Saturday.

The virtual summit was hosted by the United Nations, United Kingdom and France, five years since the Paris Climate Agreement was adopted on Dec 12 2015.

Opening the event, Antonio Guterres, secretary-general of the United Nations, stressed since the Paris Agreement, "we are still not going in the right direction" and "carbon dioxide levels are at record highs".

"I call on all leaders worldwide to declare a State of Climate Emergency in their countries until carbon neutrality is reached," he said, noting that some 38 countries have already done so.

The secretary-general said the central objective of the UN in 2021 will be to build a truly global coalition for carbon neutrality by the middle of the century.

"Every country, city, financial institution and company needs to adopt plans to reach net zero emissions by 2050, and start executing them now, including by providing clear short-term targets," Guterres said.

"Key emitting sectors such as shipping, aviation and industry must also present and implement new, transformational roadmaps in line with this goal."

The secretary-general noted that more countries are committing to zero emissions and mindsets are shifting in the right way.

"On the path to COP26, I urge everyone to show ambition, stop the assault on our planet and do what we need to guarantee the future of our children and grandchildren," he concluded.

The Summit is open to leaders who are ready to showcase ambitious new commitments, including Nationally Determined Contributions to reduce greenhouse gas emissions, strategies to reach Net Zero, climate finance pledges and innovative plans to adapt and build resilience to climate change.

It will put the world on a path to make substantial reductions in global greenhouse gas emissions ahead of the UK-hosted COP26 next November in Glasgow.

UK Prime Minister Boris Johnson said that this difficult year ends with a note of optimism, due to the unprecedented speed with which a vaccine has been produced, thanks to international efforts.

Johnson said: "Together we can use scientific advances to protect our entire planet, our biosphere, against a challenge far worse, far more destructive even than the coronavirus. And by the promethean power of our invention, we can begin to defend the earth against the disaster of global warming."

Earlier this month, Johnson announced a new Nationally Determined Contributions, committing the UK to reduce greenhouse gas emissions by at least 68 percent by the end of the decade compared to 1990 levels.

"Today, we're putting our foot to the accelerator, in a carbon-friendly way of course, with a Ten Point Plan for green industrial revolution. We want to turn the UK into the Saudi Arabia of wind power generation. Enough wind power by 2030 to supply every single one of our homes with electricity," he said on Saturday.

The UK will also end direct government support for the fossil fuel energy sector overseas.

The policy will see the country end export finance, aid funding and trade promotion for new crude oil, natural gas or thermal coal projects, with very limited exceptions.

The summit also provided a platform for civil society, young people and Indigenous Peoples representatives, many of whom disproportionately experience the impacts of climate change, to voice their concerns.

This included youth activist Selina Neirok Leem from the Marshall Islands.

Five years ago, Lemm became the youngest delegate to address the 2015 UN Climate Conference, COP21, where the landmark Paris Climate Agreement was adopted.

Leem, who has been described as a climate warrior, expressed anger and disappointment at the slow pace of change.

She told the summit that the very survival of her home is threatened by climate change and that, since Paris, temperatures have continued to rise, forest fires have continued to rage, and glaciers are still melting.

Other world leaders including Chinese President Xi Jinping, French President Emmanuel Macron, German Chancellor Angela Merkel, Justin Trudeau, Prime Minister of Canada, Narendra Modi, Prime Minister of India, and Yoshihide Suga, Prime Minister of Japan, also spoke at the event.

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