Thirteen per cent of the Earth's surface, spanning 65 countries, experienced record high temperatures in August, while the rest of the world braved significantly higher temperatures compared to the 1951-1980 average, according to a new analysis conducted by an independent US-based non-profit organisation.

Berkeley Earth, which focuses on environmental data science and analysis, said last month was the warmest August since records began to be kept in 1850, with "particularly warm conditions" prevailing in parts of India, Japan, North Atlantic, Eastern Equatorial Pacific, Northern South America, Central America, parts of Africa and the Middle East.

The National Oceanic and Atmospheric Administration (NOAA), a US government agency, said on Thursday that 2023 witnessed Earth's hottest August in its 174-year climate record.

The sizzling month also marked the northern hemisphere's warmest meteorological summer and the southern hemisphere's warmest meteorological winter on record, the NOAA's National Centres for Environmental Information said.

Berkeley Earth said August 2023 exceeded the previous record set in August 2016 by 0.31 degrees Celsius, "a surprisingly large margin, well outside the margin of uncertainty".

Its researchers said: "We estimate that 13 per cent of the Earth's surface experienced its locally warmest August average, and 87 per cent of the Earth's surface was significantly warmer when compared to its local average during the period from 1951 to 1980." In total, they estimated that 65 countries (mostly in the tropics) witnessed their warmest August on record.

These countries include Bahrain, Barbados, Brazil, Cambodia, Cameroon, Chad, China, Colombia, Cuba, Iran, Iraq, Japan, Kenya, Mexico, Morocco, Niger, Panama, Peru, the Philippines, Qatar, Russia, Rwanda, Saudi Arabia, Sri Lanka, Sudan, Suriname, Turkiye, Venezuela and Yemen.

Some of these countries broke their August records by extraordinary margins. In Ecuador, close to the strengthening El Niño, the August average temperature record was broken by more than 1.4 degrees Celsius, the analysis showed.

An El Niño condition -- periods of unusual warming of waters in the eastern tropical Pacific Ocean -- was officially declared by the NOAA in early June.

Berkeley Earth said the global mean temperature in August was 1.68 (± 0.09) degrees Celsius above the 1850-to-1900 average, which is frequently used as a benchmark for the preindustrial period.

"This is the 12th time in the Berkeley Earth analysis that any individual month has reached at least 1.5 degrees Celsius over the preindustrial benchmark. However, July and August 2023 are the only times, thus far, that a 1.5-degree Celsius anomaly has occurred during the northern hemisphere summer," it said.

One of the Paris Agreement goals has been to limit global warming to 1.5 degrees Celsius above the preindustrial (1850-1900) average.

"That goal is defined in reference to the average climate over many years, so a few individual months above 1.5 degrees Celsius do not automatically mean that the target has been exceeded.

"However, isolated anomalies above 1.5 degrees Celsius are a sign that the Earth is getting close to that limit. It is likely that global warming will cause the long-term average to exceed 1.5 degrees C during the 2030s unless significant reductions in greenhouse gas emissions are achieved soon," the non-profit, which provides open-source global air pollution data and highly accessible global temperature data, said.

Scientists say the last three months have been extraordinary in terms of global average temperatures, with new records set every month and often by a large margin.

The Berkeley Earth researchers said the global mean temperature anomaly in August exhibited a moderate increase relative to July, rising 0.08 degree Celsius. Such an increase is unsurprising during the strengthening phase of a new El Niño event.

They say that the longer recent period of warmth is driven by a combination of several man-made and natural factors acting together.

Firstly, man-made global warming has been raising the Earth's temperature by about 0.19 degrees Celsius per decade. This is a direct consequence of the accumulation of additional greenhouse gases in the atmosphere, especially carbon dioxide. This is the primary factor responsible for long-term warming, Berkeley Earth said.

However, global warming is a gradual process. It does not explain short-term spikes and fluctuations in the Earth's average temperature. The main reason for such spikes is internal variability in the distribution of heat and circulation of the oceans and atmosphere, it added.

The largest and most well-known form of short-term internal variability is an El Niño cycle or a La Niña cycle originating in the Pacific. During an El Niño phase, global average temperatures tend to be slightly higher. As a result, record highs for global average temperatures tend to be set during El Niño years. This year, a new El Niño officially began in June, after a three-year La Niña period, it said.

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