U.N. Secretary-General Antonio Guterres bluntly told leaders gathered in New York that unless current emission trends for greenhouse gases are reversed by 2020, it will be impossible to keep global warming below 1.5 degrees Celsius (2.7 degrees Fahrenheit). The target was set in the 2015 Paris agreement, but the U.N. says government commitments so far only achieve a third of the emissions cuts needed.
"Why is climate change faster than we are?" he asked. "The only possible answer is that we still lack strong leadership to take the bold decisions needed to put our economies and societies on the path of low-carbon growth and climate-resilience."
Guterres' comments echo those of climate researchers, who say the world could miss even the less ambitious goal of the Paris accord of keeping temperature increases below 2 degrees Celsius (3.6 degrees Fahrenheit) by the end of the century compared with pre-industrial times.
The U.N. chief challenged governments to end fossil fuel subsidies, help shift toward renewable energy and back a price for carbon emissions that reflects their actual cost. A recently published report by the Paris-based Organization for Economic Cooperation and Development found the cost of taxes and permits for carbon emissions among dozens of leading economies is over 76 percent below the estimated actual cost of 30 euros ($35.21) per metric ton.
Guterres said climate-related disasters already cost the world $320 billion last year, a figure likely to grow with increased warming.
He singled out the world's 20 leading and emerging economies — known as the G-20 — saying they account for about 80 percent of global greenhouse gas emissions.
As Guterres spoke at the United Nations, across town corporate leaders and government officials announced a range of programs intended to pump billions of dollars in public and private funds into what's often referred to as the "green economy," which aims to reduce the environmental impact of business.
Among them, the World Bank announced it would invest $1 billion in battery storage systems for developing and emerging economies. World Bank president Jim Yong Kim said the Washington-based institution expected to raise an additional $4 billion for the venture to triple battery storage capacity in developing countries by 2025.
French President Emmanuel Macron cautioned against governments and companies "greenwashing" unacceptably high carbon emissions with big-figure promises, citing the pledge by rich countries to mobilize $100 billion a year by 2020 to help poor nations tackle global warming.
That target is unlikely to be met, especially if the United States — which under President Donald Trump announced its withdrawal from the Paris accord — doesn't contribute its share.
Jacinda Ardern, the prime minister of New Zealand, told the meeting of her recent visit to small Pacific island nations that are already suffering the effects of climate change.
"None of us can opt out of severe weather events or rising sea levels, so nor should we have the ability to opt out of action either," she said.
New Zealand is one of several countries considering enshrining in law a goal of ending all greenhouse gas emissions by 2050.
The coming months will see a flurry of negotiations over the rules that countries will have to follow as part of their commitment to the Paris accord. Signatories have set themselves a deadline of agreeing to rules by the time leaders meet in Katowice, Poland, in December.