July 21 was world's hottest day in at least 84 years: European climate agency

New Delhi: The Earth experienced its hottest day in at least 84 years, with the global average temperature reaching a record high of 17.09 degrees Celsius on July 21, according to the European Union's Copernicus Climate Change Service (C3S).

This follows a series of monthly heat records -- June marked the 12th consecutive month of global temperatures reaching or exceeding the 1.5 degrees Celsius threshold. Every month since June last year has been the warmest on record.

Preliminary data from C3S showed that July 21 was the hottest day since at least 1940, surpassing the previous record of 17.08 degrees Celsius set on July 6, 2023.

What stands out is the significant difference between the temperatures since July 2023 and all previous years.

Before July 2023, the Earth's daily average temperature record, set in August 2016, was 16.8 degrees Celsius. However, since July 3, 2023, there have been 57 days with temperatures exceeding that previous record.

Carlo Buontempo, director of C3S, said the difference between the temperatures over the past 13 months and previous records is staggering.

"We are now in truly uncharted territory and as the climate continues to warm, we are bound to see new records in the coming months and years," he said.

Analysis shows that 2023 and 2024 have seen significantly higher annual maximum daily global temperatures compared to previous years. The 10 years with the highest daily average temperatures are from 2015 to 2024.

The global average temperature usually peaks between late June and early August, driven by the northern hemisphere's summer. The land masses in the northern hemisphere warm up faster than the southern hemisphere's oceans can cool down.

With global average temperatures already at near-record levels, a new daily average temperature record was not completely unexpected.

C3S scientists attributed the sudden rise in daily global temperatures to much higher-than-average temperatures over large parts of Antarctica. Such large anomalies are not uncommon during the Antarctic winter and also contributed to record global temperatures in early July 2023.

The Antarctic Sea ice extent is almost as low as it was last year, leading to above-average temperatures over parts of the Southern Ocean.

As the global average temperature typically peaks between late June and early August, scientists expect it to rise and peak around July 22 or 23, 2024, before decreasing.

The European climate agency said whether 2024 will be the warmest year ever depends largely on the development and intensity of La Niña. While 2024 has been warm enough to surpass 2023, the exceptional warmth of the last four months of 2023 makes it too early to predict with certainty which year will be warmer.

Climate science non-profit Berkeley Earth estimated last week that 2024 has a 92 per cent chance of setting a new annual heat record.

There is a 99 per cent chance that 2024 will have an annual average temperature anomaly of more than 1.5 degrees Celsius above the 1850-1900 average, it said.

At the 2015 UN climate talks in Paris, world leaders committed to limiting the global average temperature rise to 1.5 degrees Celsius above the pre-industrial period average to avoid the worst impacts of climate change. However, a permanent breach of the 1.5-degree Celsius limit specified in the Paris Agreement refers to long-term warming over a 20 or 30-year period.

The Earth's global surface temperature has already increased by around 1.2 degrees Celsius due to the rapidly-increasing concentration of greenhouse gases, primarily carbon dioxide and methane, in the atmosphere. This warming is considered to be the reason behind record droughts, wildfires and floods worldwide.