Unprecedented Temperature Anomalies in 2023

The magnitude of this temperature surge was significant, with September 2023 being approximately 1.75°C warmer than the September average during the preindustrial reference period of 1850-1900. The momentum of rising temperatures persisted throughout the year, with the global temperature for January to September 2023 surpassing the average by 0.52°C and even surpassing the warmest calendar year, 2016, by 0.05°C. This cumulative effect has propelled 2023 to be a staggering 1.40°C warmer than the preindustrial average of 1850-1900.

Over land, Unusually high temperatures were observed in various regions, including the North Atlantic, Eastern Equatorial Pacific, South America, Central America, Europe, sections of Africa and the Middle East, Japan, and Antarctica. A total of 77 countries, primarily located in Europe and tropical regions, established new September monthly average temperature records. Europe , Europe, for example, experienced a rise of approximately 2.5°C above the 1991-2020 average, breaking the previous September 2020 record by 1.1°C.

The average sea surface temperature over 60°S-60°N in September reached 20.92°C, the highest on record for September and the second highest overall, trailing only August 2023. whereas Antarctic sea ice extent remained at a record low for the time of year, and both daily and monthly extents reached their lowest annual maxima in the satellite record in September, with the monthly extent 9% lower than average.

The Complex Factors Behind the Warming

The September temperature surge was primarily driven by increased warmth around the Antarctic Circle. Nevertheless, the exceptional warmth in September resulted from more than just the recent surge; it also stemmed from the extraordinary warmth experienced in the preceding months.

While temperature fluctuations around Antarctica in the past month could be attributed to natural variability, the broader changes in 2023 can be attributed to a combination of both human-made and natural factors. Firstly, human-induced global warming has been steadily raising Earth's temperature, increasing at a rate of about 0.19 °C per decade (0.34 °F per decade). This is a direct consequence of the accumulation of additional greenhouse gases in the atmosphere, particularly carbon dioxide, making it the primary factor contributing to long-term warming.

However, global warming is a gradual process and does not account for short-term temperature spikes and fluctuations in Earth's average temperature. These short-term variations are primarily caused by internal variability in heat distribution and atmospheric and oceanic circulation patterns. One of the most significant short-term internal variability sources is the El Niño/La Niña cycle originating in the Pacific Ocean. During an El Niño phase, global average temperatures tend to be slightly higher, often resulting in record-high global average temperatures. In 2023, a new El Niño officially began in June, following a multiple-year period of La Niña. The rapid transition from a relatively strong La Niña to the current El Niño has played a significant role in this year's warming.

One of the Paris Agreement's goals has been to keep global warming to no more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels. Because that target is defined in terms of average climate over many years, a few individual months or a single year above 1.5 °C do not automatically imply that the target has been exceeded. However, isolated anomalies above 1.5 °C indicate that the Earth is approaching that limit. Unless significant reductions in greenhouse gas emissions are achieved soon, global warming will likely cause the long-term average to exceed 1.5 °C during the 2030s.

It is highly likely that 2023 will become the warmest year on record since instrumental measurements began. The unexpectedly robust warming observed from June through September 2023, combined with the prospect of a strong El Niño event, has raised the forecast for the remainder of the year.

Credit : CBC News: The National

In September 2023, the world witnessed a climatic milestone as it recorded the highest global temperatures ever documented for that particular month. The average surface air temperature for September reached 16.38°C, which was a striking 0.93°C above the 1991-2020 average for the same month and an unprecedented 0.5°C above the previous warmest September in 2020. This notable feat solidified September 2023 as the most anomalously warm month on record since 1940, based on the Berkley Earth* dataset.

Source : https://berkeleyearth.org

Source : https://berkeleyearth.org

*Berkeley Earth is a Berkeley, California-based independent 501(c)(3) non-profit focused on land temperature data analysis for climate science.