880. Heat Wave and Drought in South America

On October 13, the National Oceanic and Atmospheric Administration (NOAA) announced that September 2023 was the hottest September on record in 174 years. The average temperature for September 2023 was 1.44°C above the 20th-century average of 15°C, marking the largest deviation from the long-term average and surpassing the average July temperature from 2001-2010 in terms of extremes. This year marked the fourth consecutive month, starting in June, to set a new monthly maximum temperature, potentially making 2023 the hottest year since NOAA began recording climate data.

In September, Africa, Europe, North America, and South America recorded the highest temperatures, with central and northern Brazil experiencing an exceptional heat wave that exceeded 40°C in mid-September.

On October 10, World Weather Attribution, an organization that studies the link between extreme events and climate change, released a report detailing the effects of climate change in response to an extraordinary 1-in-30-year heat wave. This heat wave coincided with the onset of spring in the Southern Hemisphere. The analysis showed that without climate change, the temperature during the heat wave would have been 1.4°C to 4.3°C lower. The report also found that the warming caused by fossil fuel combustion increased the likelihood of a heat wave by nearly 100 times. With future warming, similar heat waves are projected to become about five times more likely and could be 1.1-1.6°C hotter. It has been noted that while the El Niño phenomenon affects weather patterns over a wide area, its influence on extreme heat waves is comparatively small compared to the effects of climate change.

Recent reports have also highlighted severe drought conditions in the Amazon River basin in Brazil. There is also growing concern about the impact of climate change on the tropical forests of the Amazon, the world's most biodiverse ecosystem.

Contributor: IIYAMA Miyuki (Information Program)