The world is losing the race against climate change, “but it is a race we can win”, UN secretary general Antonio Guterres has warned a summit on tackling the issue.

The UN estimates there needs to be between a three-fold and five-fold increase in efforts to cut greenhouse gases, to prevent global temperatures rising more than 1.5C above pre-industrial levels and avoid the worst impacts of climate change.

The climate action summit in New York aims to galvanise efforts by countries and businesses to close the gap between what is needed to curb global warming and current policies, which put the world on track to warm by more than 3C.

Mr Guterres, who convened the conference, said: “The best science, according to the Intergovernmental Panel on Climate Change, tells us that any temperature rise above 1.5C will lead to major and irreversible damage to the ecosystems that support us.

“Science tells us that on our current path, we face at least 3C of global heating by the end of the century.

“The climate emergency is a race we are losing, but it is a race we can win.”

As leaders gather for the summit, which comes in the wake of protests that saw millions of people led by school children take to the streets around the world calling for action, countries and businesses are bringing forward announcements on what steps they will take.

These include an alliance of some of the world’s largest pension funds and investors, responsible for directing more than 2.4 trillion US dollars (£1.9 trillion), who have committed to making their investment portfolios carbon neutral by 2050.

Inger Andersen, executive director of the UN Environment Programme (UNEP) said: “There are no short-cuts to decisive climate action. We need to take a long-term view.

“I applaud the leadership of the investors in this alliance.

“Their commitment sends a strong signal that financial markets and investors are listening to science, and moving us to a path of resilience and sustainability.”

Prime Minister Boris Johnson is announcing that scientists will be able to use up to £1 billion of the aid budget inventing new technology to tackle the climate crisis in developing countries, alongside funding to protect wildlife.

Environmental groups and agencies said the measures were not sufficient to tackle the planetary emergency and should not be at the expense of helping people out of poverty – and called for moves to shift away from fossil fuels.

As Mr Johnson attends the summit in New York, a group of mothers has staged a pushchair protest and “climate rhyme time” action outside Downing Street and the London headquarters of Shell and BP calling for them to keep polluting fossil fuels in the ground.

The protest included a sing-along of reworked children’s songs and nursery rhymes such as Old King Coal, Amazon’s Burning, and the Climate Hokey Cokey, and forms part of the global week of action which kicked off with climate strikes on Friday.

A mother cries while she holds her baby during a protest organised by Mothers Rise Up at Downing Street
A mother cries while she holds her baby during a protest organised by Mothers Rise Up at Downing Street (Aaron Chown/PA)

Maya Mailer from Mothers Rise Up, the group of UK mothers behind the action, said: “Millions of people – inspired by the young climate strikers – are demanding climate action, yet the UK Government, and companies like Shell and BP are continuing to champion oil and gas with scant regard for our planet, or our children’s future.

“We are terrified mothers and we are appealing to Boris Johnson, and the bosses of Shell and BP, to start treating the climate crisis like the emergency it is: pull the plug on fossil fuels and massively ramp up investment in clean renewable energy