Global Climate Change in September and October 2023
Record warmth in September
The remarkable and unprecedented surge in global temperature which began in June, continues unabated, and has actually increased since August. September smashed the record for the most extreme record month, with an anomaly of 1.47 C higher than the 1951-80 average, and 0.49 C higher than the previous record of +0.98 C, set in 2020. A total of 77 countries around the world experienced their warmest September on record. At Montoro, near Cordoba, Spain, Europe recorded its highest ever September temperature of 45.7 C, on the 5th, and countries from Spain to Poland recorded their hottest ever September. A spokesman for Meteo-France said heatwaves were now occurring outside the high summer months of July and August. Miami experienced 178 hours during September, when the heat index surpassed 105 F (45.6 C), described as “beyond unprecedented”. The old record was 49 hours in 2020. A climatologist at the Berkeley Earth climate data project declared that “September was, in my professional opinion, absolutely gobsmackingly bananas”.
October/November and El Nino
Globally, October was also record warm. The anomaly was less than September’s, but on a par with the July and August anomalies, at 1.34 C warmer than the 1951-80 average. This beat the previous record of +1.09 C, set in 2015, by 0.25 C. At the time of writing (Nov 16), November is well on track to be the warmest on record, and the current daily anomaly is as high as the highest seen in September. January to October 2023 has been the warmest on record, and 2023 is certain to be the warmest year since records began, and probably since before the last Ice Age, 125,000 years ago. The ongoing El Nino in the Pacific is currently at +1.8 C above normal, which is strong, and just 0.2 C below the ‘very strong’ threshold. The second year of a strong El Nino invariably sets a new global temperature record, so 2024 will probably exceed the 2023 global temperature record.
On October 24, 24 hours before landfall near Acapulco, on Mexico’s west coast, the National Hurricane Center in Miami were predicting that Otis would be only a tropical storm at landfall. Otis had other ideas, and intensified from a 65 mph tropical storm to a landfalling category 5 hurricane, with sustained winds of 165 mph, on October 25. It was the strongest known hurricane ever to hit Mexico’s west coast. Fatalities and damage costs are still very uncertain. Officially, the Mexican government has said that there were 48 fatalities, with at least 58 still missing, but the figures are disputed by locals. On November 12, a report emerged from Acapulco’s funeral homes estimating a death toll of at least 350. Damage was estimated at between $11.5 and $17 billion, making it the costliest hurricane in Mexico’s history. Otis was the world’s 9th category 5 storm in 2023. The average for a year is 5.3. Model predictions are, to some extent, based on historical precedent, and the failure of the models to predict the storm’s extreme rapid intensification led some observers to conclude that computer models may not be up to the job of predicting hurricane intensity in a changing world.
Peak of Solar Cycle 25 Imminent
The sun has a roughly 11 year cycle of activity. Solar Cycle 25 is the current Solar Cycle, the 25th since 1755, when continuous monitoring of solar sunspot activity began. Sunspot numbers are a proxy indicator for increased solar activity. More sunspots are seen when the sun is more active. Solar Cycle 24 was the weakest maximum in 100 years. Since weak maxima usually occur in consecutive cycles, Solar Cycle 25 was predicted to be a weak event, but recent auroral displays, seen as far south as southern Europe, indicate that it could be above average. Solar Cycle 25 is expected to peak sometime between January and October 2024. The contribution that an above average maximum can make to global temperature is modest – perhaps around 0.1 C, while a very strong El Nino, like the 2015-16 event, can make a difference of up to 0.3 C. Nevertheless, the peak of Solar Cycle 25 will contribute to the expected record global temperature of 2024.
H5N1 Avian Flu in Antarctica
The devastating spread of H5N1 bird flu around the world has particularly affected birds that nest in dense colonies, such as gannets, and carrion feeders, such as skuas. In a previous post I predicted that it was only a matter of time before it spread to the Galapagos Islands and Antarctica. It was reported from the Galapagos Islands in September, and from Bird Island, near South Georgia, in October. Technically, South Georgia is part of Antarctica, so it can now be said to have spread to that continent. But, South Georgia is actually further from the Antarctic mainland than the southern tip of South America, where it has been causing mass mortality in both birds and seals for some time. It is believed to have been carried to South Georgia from Argentina by brown skuas, and these birds also migrate from South America to Antarctica in the southern hemisphere summer, so it is probably now on the Antarctic mainland, but not yet detected due to the small number of people there. Skuas predate on penguin chicks and eggs. Their counterpart, in the northern hemisphere, including Scotland, is the great skua, whose population has been greatly reduced by H5N1. Since penguins congregate in dense colonies, they will probably be particularly susceptible to H5N1 transmitted by skuas, as will the various species of seals.
W. Davidson, November, 2023
This section: Pat's Home Page Blog, Science: Climate Change and Other Topics
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- Artists’ Christmas Fayre
- Global Climate Change in September and October 2023
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