"From 1850, global temperature has increased by 0.06°C per decade. But 1.5°C warming can occur temporarily in the near future and long-term stabilising of 1.5°C warming [can occur] around the 2060s. Any incremental increase in global temperatures is catastrophic. An increase of 1°C in temperatures increases the moisture content in the atmosphere by 7%. We should try to contain the further increase in global temperatures immediately,” said M Rajeevan, former secretary, ministry of earth sciences.

“Preliminary records show that we have already crossed the 1.5°C-level for a few days this year. Since the El Nino — which acts as a mechanism to transfer the heat from the ocean to the atmosphere across the globe — will peak in December and continue to the next year, we might see more of these record-breaking temperatures,” said climate scientist Roxy Mathew Koll.

Also Read: Cause and Effect | A climate crisis glossary to keep handy

June, July, August and September were the four warmest months on record. According to air temperature data records maintained and analysed by the University of Maine's Climate Reanalyzer, since June this year, temperatures have been significantly above the long-term mean of 1979 to 2000, and possibly highest ever.

Here’s a month-wise list of all the records this year made till September.

January: This January was the third warmest in Europe. Much of Europe had above-average air temperatures, especially the Balkans and eastern Europe, where New Year's Day experienced record warmth; the Svalbard region was also very warm. Antarctic sea ice extent reached its lowest value for January in the satellite dataset, at 31% below average, well below the previous record of January 2017.

February: The Antarctic sea ice reached its lowest monthly extent in the satellite data record, at 34% below the average for February, breaking the previous record of February 2017.

March: The Antarctic sea ice extent was the second lowest for March in the satellite data record, at 28% below average.

April: The Antarctic sea ice extent remained well below average, at -19%, ranking third lowest for April in the satellite data record. The Arctic and Antarctic are the world’s refrigerators. Since they are covered in white snow and ice that reflect heat back into space, they balance out other parts of the world that absorb heat. Less ice means less reflected heat, meaning more intense heat waves worldwide, according to an explainer by the World Wildlife Fund for Nature (WWF).

May: This month was 0.40°C warmer than the 1991-2020 average for May — the joint second warmest May (joint because there is another year with similar warming). It was about 0.07°C cooler than May 2020, the warmest May on record.

June: June 2023 was the warmest June globally by a large margin at 0.53°C above average. June was the first time that global surface air temperatures exceeded the pre-industrial level by more than 1.5⁰C during the month of June according to data maintained by Copernicus Climate Change Service.

July: Global surface air temperature for July was the highest on record for any month in the ERA5 dataset going back to 1940. July was around 1.5°C warmer than the 1850-1900 average. The data measures temperatures near the surface of the earth.

August: August was the warmest month of August in the ERA5 data record since 1940, as well as the second warmest month after July 2023. The global mean surface air temperature during August 2023 was 16.82°C, 0.71°C warmer than the 1991-2020 average for August, and 0.31°C warmer than the previous warmest August, in 2016. The month is estimated to have been around 1.5°C warmer than the preindustrial average for 1850-1900.

September: Hottest September on record. September had an average surface temperature of 16.38°C. This was 0.5°C above the temperature of the previous warmest September, in 2020, and around 1.75°C warmer for the month of September compared to the pre-industrial reference 1850-1900 period.

Summer 2023

The June-July-August (JJA) season for 2023 was the warmest on record globally by a large margin, with an average temperature of 16.77°C, 0.66°C above average. JJA 2023 has seen record-breaking high sea surface temperature (SST) anomalies in the North Atlantic and for the global ocean. This summer saw marine heatwaves in several areas around Europe, including around Ireland and the UK in June, and across the Mediterranean in July and August.

"The unprecedented temperatures for the time of year observed in September - following a record summer - have broken records by an extraordinary amount. This extreme month has pushed 2023 into the dubious honour of first place - on track to be the warmest year and around 1.4°C above pre-industrial average temperatures. Two months out from COP28 – the sense of urgency for ambitious climate action has never been more critical,” said Samantha Burgess, Deputy Director of the Copernicus Climate Change Service in a statement last week.

Sea surface temperatures

Every day from July 31 to August 31 saw global average sea surface temperatures exceed the previous record of March 2016. August, as a whole, saw the highest global monthly average sea surface temperatures on record across all months, at 20.98°C, and was well above average for August, with an anomaly of 0.55°C.

“Since June, the world has experienced unprecedented heat on land and sea. The temperature anomalies are enormous – far bigger than anything we have ever seen in the past. Antarctic winter sea ice extent was the lowest on record for the time of year. What is especially worrying is that the warming El Niño event is still developing, and so we can expect these record-breaking temperatures to continue for months, with cascading impacts on our environment and society,” Petteri Taalas, World Meteorological Organisation (WMO) Secretary-General said last week.