Search Climate Insights Directory

The analysis finds that heat and cold extremes are warming globally in line with average temperatures, with cold extremes in Siberia and Canada warming particularly fast. Extreme daily precipitation is generally increasing at a rate of approximately 7% per degree Celsius, though regional variations exist. While trends in tropical cyclone frequency are difficult to determine, their impacts have increased due to higher precipitation and sea level rise. Drought trends remain complex and highly dependent on the specific definition used.

A scientific analysis of the December 2015 Chennai floods found no detectable effect of human-induced climate change on the extreme one-day rainfall event, likely due to the masking effect of aerosol pollution in the region.

The analysis concludes that human-caused climate change increased the frequency of extreme three-day precipitation events like the August 2016 Louisiana downpours by at least 40% and increased their intensity by approximately 10%. Using observational data and high-resolution climate models (FLOR-FA and HiFLOR), the study found that such events are now more likely and intense than they were in 1900. While the specific local event was characterized as a 1-in-550 year occurrence, similar events now occur somewhere along the Central U.S. Gulf Coast region approximately once every 30 years.

The study investigated the December 1, 2015, rainfall event in Chennai, where some stations recorded up to 494 mm of rain in 24 hours, causing an estimated US $3 billion in economic costs. Using observational data and regional climate models, researchers found no detectable effect of human-induced climate change on the probability of this extreme one-day rainfall. The analysis suggests that the cooling effect of aerosols in the western Bay of Bengal likely counteracted greenhouse gas warming, while non-anthropogenic factors, such as El Niño and sea surface temperature anomalies, played a more significant role.

The study investigates a severe drought in southern Madagascar (the Grand Sud region) between July 2019 and June 2021, which contributed to a major food security crisis. Analysis of observational data and climate models indicates that the event was a 1-in-135 year dry event, but its likelihood was not significantly increased by anthropogenic climate change. The findings suggest that natural variability remains the dominant driver of such droughts in this region, aligning with IPCC projections that perceptible changes in drought may only emerge if global mean temperatures exceed 2°C above pre-industrial levels. The report also highlights that the humanitarian impact was severely compounded by extreme poverty, poor infrastructure, and the COVID-19 pandemic.