The national capital recorded a minimum temperature of 28 degrees Celsius, one notch above the season's average, on Sunday, weather officials said.
Most global leaders committed to taking actions that would limit global warming to 1.5ºC and below 2ºC by the end of the century.
Scientists say Antarctic ice sheet has physical tipping points, beyond which ice loss can accelerate out of control.
"Below normal seasonal maximum temperatures are likely over most of the subdivisions of south peninsula and adjoining central India," said IMD
WMO said the differences in average global temperatures among the three warmest years, 2016, 2019 and 2020, were indistinguishably small
Extreme heat is already killing more people than reported. By 2030, it could also result in productivity loss equivalent to 34 million jobs, writes Bhasker Tripathi
Some major roads heading to the south and west from Sydney were closed for part of the day and authorities asked people to delay travel at the start of the Christmas holiday period
Each of the last four decades has been hotter than the last
But 2015 saw the worst heatwave in India since 1992, striking areas from Delhi to Telangana and killing 2,081 people. It was the fifth deadliest in world history
Searing heatwaves saw records tumble across Europe last month, with unusually high temperatures within the Arctic Circle as well
When the air temperature exceeds 35°C, the body relies on the evaporation of water - mainly through sweating - to keep core temperature at a safe level
The World Meteorological Organization said this week that 2019 was on track to be among the world's hottest years, and 2015-2019 would then be the hottest five-year period on record
Warming trends are strongest in the Arctic region, where 2018 saw the continued loss of sea ice
This was the second highest value for January-June in the 1880-2017 record