UN warns climate crisis now irreversible

Meanwhile annual coastal flood damages are projected to increase 100 to 1000 times by 2100, and some island nations are ‘‘likely to become uninhabitable’’.

Hans-otto Portner, another IPCC expert, said: ‘‘There are large uncertainties about tipping points that may be ahead of us, but for some systems, especially biological evidence in the oceans, we have already evidence that the tipping point has been passed.’’ The warnings come as the UK government announced an international coalition to push for at least 30 per cent of oceans to be protected areas by 2030.

Ministers say the move helps sensitive species such as seahorses, turtles and corals to thrive, and can fight climate change by protecting key habitats for storing carbon such as mangrove forests and seagrass meadows.

Historically, the Antarctic Ocean has an ice-free September only once every 100 years or so, however if global temperatures rise to two degrees above preindustrial levels this would become as frequent as every three years, the panel said. The 2015 Paris accord commits signatories to adopting policies intended to keep warming to within 1.5C. However, Donald Trump has since withdrawn the US from the agreement.

In one of her last acts as prime minister, British Prime Minister Theresa May in June set a legallybinding target to cut greenhouse gasses to net zero by 2050.

Last year, a separate IPCC report called for 45 per cent reductions in carbon emissions by 2030.

Hoesung Lee, chairman of the body, said yesterday: ‘‘If we reduce emissions sharply, consequences for people and their livelihoods will still be challenging, but potentially more manageable for those who are most vulnerable.’’ – Telegraph Group National leaders have rebuked Greta Thunberg after the climate campaigner criticised their inaction and started a legal challenge against France and Germany’s environmental policies.

President Emmanuel Macron and German Chancellor Angela Merkel, who had both previously endorsed Thunberg’s Fridays for Future school strike movement, were stung into reacting to what one French minister termed her ‘‘despair ... verging on hatred’’.

Scott Morrison, 51, the prime minister of Australia and a fossil fuels enthusiast, also accused her of stirring up ‘‘needless anxiety’’ among his country’s children.

In an uncompromising speech at the United Nations, Thunberg, pictured, told the world’s politicians that they had ‘‘stolen my dreams and my childhood