Some 60 world leaders are set to attend a major UN climate summit in New York and deliver their pledges to reduce carbon-dioxide emissions.
French President Emmanuel Macron and British Prime Minister Boris Johnson will be among those expected to take the podium, but some key leaders, including U.S. President Donald Trump, will not take part.
UN Secretary-General Antonio Guterres has pushed for countries to move away from fossil fuels and to stop building new coal-fired power stations after 2020.
'The climate emergency is a race we are losing, but it is a race we can win,' he said in a statement.
Ahead of the one-day Climate Action Summit, which comes ahead of international climate negotiations next year, the UN said 66 countries had signaled their intent to achieve net zero emissions by 2050.
The 2015 Paris Agreement pledged to keep global temperatures 'well below' 2 degrees Celsius above preindustrial times and 'endeavor to limit' them even more, to 1.5 degrees.
However, scientists have warned that the signs and impacts of global warming are speeding up.
The World Meteorological Organization says global temperatures have risen by 1.1 degrees since 1850, and gone up by 0.2 degrees between 2011 and 2015.
The amount of greenhouse gas going into the atmosphere between 2015 and 2019 had grown by 20 percent compared to the previous five years, it says in a report published on September 23.
Based on reporting by AFP and the BBC
Copyright (c) 2018. RFE/RL, Inc. Republished with the permission of Radio Free Europe/Radio Liberty, 1201 Connecticut Ave NW, Ste 400, Washington DC 20036