{"query_echo":{"q":"","filters":{"analysis_type":["extreme event attribution"]},"warnings":[{"code":"facet_value_not_in_vocabulary","message":"Value 'extreme event attribution' for facet 'analysis_type' is not in the controlled vocabulary."}]},"total":{"value":5,"relation":"eq"},"page":1,"page_size":20,"self":"https://climateinsightsdirectory.org/api/v1/search?analysis_type=extreme+event+attribution","stability":"beta","ai_marking":{"digital_source_type":{"uri":"http://cv.iptc.org/newscodes/digitalsourcetype/trainedAlgorithmicMedia","name":"Created using Generative AI"},"notice":"Summary and key insights are generated using artificial intelligence."},"results":[{"id":"wwatt-000004","url":"https://climateinsightsdirectory.org/document/wwatt-000004","title":"Trends in weather extremes","publisher":{"name":"World Weather Attribution","organization":"world-weather-attribution"},"document_type":"research paper","language":"en","date_published":"2018-02-28","source_url":"https://www.worldweatherattribution.org/trends-in-weather-extremes-february-2018/","generator":"Climate Insights Directory","generated_fields":["summary","key_insights","climate_tags","geography_discussed","analysis_type"],"summary":{"text":"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.","ai_generated":true,"unit":"wwatt-000004#summary","date_modified":"2026-10-23"},"key_insights":[{"text":"Heat extremes, defined as the highest daily average temperature of the year, have increased almost everywhere compared to a century ago. Exceptions include the eastern U.S., where current extremes are similar to the 1930s Dust Bowl, and India, where air pollution and irrigation have counteracted greenhouse gas warming since the 1970s.","ai_generated":true,"unit":"wwatt-000004#insight-1","date_modified":"2026-10-23"},{"text":"Cold extremes, measured by the coldest daily average temperature of the year, are warming faster than heat extremes, with some increases reaching five times the global mean temperature. The most significant increases over land are observed in Canada and Siberia.","ai_generated":true,"unit":"wwatt-000004#insight-2","date_modified":"2026-10-23"},{"text":"The highest daily precipitation of the year has increased at more stations than it has decreased. The average increase is approximately 7% per degree Celsius, aligning with the Clausius–Clapeyron relation, although regional deviations occur in Colorado, the Mediterranean, and northwestern Europe.","ai_generated":true,"unit":"wwatt-000004#insight-3","date_modified":"2026-10-23"},{"text":"While trends in the number and intensity of tropical cyclones are difficult to establish due to improved observing systems and decadal variability, their physical impacts have increased. This is driven by higher storm surges from sea level rise and increased extreme precipitation, such as a 15% increase on the U.S. Gulf Coast over the last century.","ai_generated":true,"unit":"wwatt-000004#insight-4","date_modified":"2026-10-23"},{"text":"General statements about drought trends are difficult because they depend on the definition used: meteorological (absence of rain), agricultural (soil moisture deficit), hydrological (water transport), or socio-economic (water shortage for societal use). For example, hydrological droughts in California can be caused by temperature increases reducing spring snowpack.","ai_generated":true,"unit":"wwatt-000004#insight-5","date_modified":"2026-10-23"}],"climate_tags":["tropical cyclone","drought","sea level rise","storm surge","greenhouse gas"],"geography_discussed":["United States","India","Africa","Siberia","Canada","Colorado","Mediterranean Sea","Europe","California"],"frame_perspective":[],"analysis_type":["trend analysis","extreme event attribution"]},{"id":"cdkn-000905","url":"https://climateinsightsdirectory.org/document/cdkn-000905","title":"Chennai, India","publisher":{"name":"Climate and Development Knowledge Network","organization":"climate-and-development-knowledge-network"},"document_type":"executive summary","language":"en","date_published":"2017","source_url":"https://cdkn.org/sites/default/files/files/CDKN_RRA_Chennai_Floods_proof5.pdf","generator":"Climate Insights Directory","generated_fields":["summary","key_insights","climate_tags","geography_discussed","analysis_type"],"summary":{"text":"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.","ai_generated":true,"unit":"cdkn-000905#summary","date_modified":"2026-10-23"},"key_insights":[{"text":"On 1 December 2015, Chennai experienced record rainfall, with some stations recording as much as 494 mm (19.45 inches) in 24 hours. This event was meteorologically extreme, with a probability of occurrence in the current climate estimated between one in 600 and one in 2,500 per year.","ai_generated":true,"unit":"cdkn-000905#insight-1","date_modified":"2026-10-23"},{"text":"The scientific analysis concluded that human-induced climate change had no detectable effect on the extreme one-day rainfall in Chennai on 1 December 2015, covering periods from 1900-1970 and 1970-2014.","ai_generated":true,"unit":"cdkn-000905#insight-2","date_modified":"2026-10-23"},{"text":"The lack of detectable human-caused influence is attributed to the 'aerosol effect,' where high levels of aerosol pollution (the 'brown cloud') block sunlight and counteract the warming effects of greenhouse gases, particularly in the western Bay of Bengal.","ai_generated":true,"unit":"cdkn-000905#insight-3","date_modified":"2026-10-23"},{"text":"The 2015 rainy season occurred alongside several climatic factors, including a strong El Niño, record warm global surface temperatures, and high Indian Ocean temperatures. SST-forced regional models showed a small but clear increase in the probability of extremes associated with El Niño and other non-anthropogenic SST anomalies.","ai_generated":true,"unit":"cdkn-000905#insight-4","date_modified":"2026-10-23"},{"text":"Chennai's high vulnerability to the floods was exacerbated by unplanned urban growth, including an estimated 150,000 illegal buildings, the loss of water bodies, encroachment of drainage channels, and inadequate flood zone planning and desilting.","ai_generated":true,"unit":"cdkn-000905#insight-5","date_modified":"2026-10-23"},{"text":"The economic costs to India resulting from the flood waters in Chennai are estimated at US$3 billion.","ai_generated":true,"unit":"cdkn-000905#insight-6","date_modified":"2026-10-23"}],"climate_tags":["extreme event attribution","greenhouse gas","aerosol","sea surface temperature","El Niño southern oscillation","Flood risk management"],"geography_discussed":["Bay of Bengal","Indian Ocean"],"frame_perspective":[],"analysis_type":["extreme event attribution"]},{"id":"wwatt-000022","url":"https://climateinsightsdirectory.org/document/wwatt-000022","title":"Louisiana Downpours August 2016","publisher":{"name":"World Weather Attribution","organization":"world-weather-attribution"},"document_type":"research paper","language":"en","date_published":"2016-08-14","source_url":"https://www.worldweatherattribution.org/louisiana-downpours-august-2016/","generator":"Climate Insights Directory","generated_fields":["summary","key_insights","climate_tags","geography_discussed","analysis_type"],"summary":{"text":"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.","ai_generated":true,"unit":"wwatt-000022#summary","date_modified":"2026-10-23"},"key_insights":[{"text":"Human-caused climate change has increased both the frequency and intensity of extreme three-day precipitation events in the Central U.S. Gulf Coast region. Specifically, an event like the August 12–14, 2016, downpour is now expected to occur at least 40 percent more often than in the pre-industrial past, with precipitation intensity increasing by roughly 10 percent.","ai_generated":true,"unit":"wwatt-000022#insight-1","date_modified":"2026-10-23"},{"text":"The August 2016 event was characterized by extreme rainfall totals, with Baton Rouge receiving 11.24 inches on August 12 alone. The total rainfall for the state was estimated at 7.1 trillion gallons, which exceeded the rainfall from Hurricane Isaac in 2012 and was three times the amount seen during Hurricane Katrina in 2005.","ai_generated":true,"unit":"wwatt-000022#insight-2","date_modified":"2026-10-23"},{"text":"There is a significant difference between the return time of such an event at a single location versus the regional scale. Locally, the event is estimated as a 1-in-550 year event, whereas a comparable event now occurs somewhere within the Central U.S. Gulf Coast region approximately once every 30 years.","ai_generated":true,"unit":"wwatt-000022#insight-3","date_modified":"2026-10-23"},{"text":"The study utilized a combination of observational data from 324 GHCN-D stations and NOAA gridded analysis, alongside two high-resolution climate models: FLOR-FA (50km resolution) and HiFLOR (25km resolution). The HiFLOR model showed a greater magnitude of shift in probabilities than the FLOR-FA model.","ai_generated":true,"unit":"wwatt-000022#insight-4","date_modified":"2026-10-23"},{"text":"Projections indicate that if greenhouse gas concentrations continue to increase as expected, the probability of extreme precipitation events like the one observed in August 2016 will further increase by the end of the current century.","ai_generated":true,"unit":"wwatt-000022#insight-5","date_modified":"2026-10-23"}],"climate_tags":["extreme event attribution","flood","greenhouse gas","climate modeling"],"geography_discussed":["Baton Rouge","Mississippi","Florida","United States"],"frame_perspective":[],"analysis_type":["extreme event attribution","statistical analysis","climate simulation"]},{"id":"wwatt-000042","url":"https://climateinsightsdirectory.org/document/wwatt-000042","title":"Chennai floods December 2015","publisher":{"name":"World Weather Attribution","organization":"world-weather-attribution"},"document_type":"research paper","language":"en","date_published":"2015-12-01","source_url":"https://www.worldweatherattribution.org/chennai-floods-december-2015/","generator":"Climate Insights Directory","generated_fields":["summary","key_insights","climate_tags","geography_discussed","analysis_type"],"summary":{"text":"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.","ai_generated":true,"unit":"wwatt-000042#summary","date_modified":"2026-10-23"},"key_insights":[{"text":"The rainfall event on December 1, 2015, was meteorologically extreme, with the highest recorded daily rainfall of 494 mm having a probability of occurrence in the current climate of between one in 600 and one in 2500 per year (95% confidence level).","ai_generated":true,"unit":"wwatt-000042#insight-1","date_modified":"2026-10-23"},{"text":"Analysis of observational data and SST-forced regional models indicates that human-caused emissions did not influence the extreme one-day rainfall in Chennai on December 1, 2015, for the periods 1900–1970 or 1970–2014.","ai_generated":true,"unit":"wwatt-000042#insight-2","date_modified":"2026-10-23"},{"text":"The lack of attribution to human-caused factors is likely due to the opposing effects of greenhouse gases and aerosols; specifically, air pollution (the 'brown cloud') has limited the increase of sea surface temperatures in the northern and western Bay of Bengal over the last 35 years.","ai_generated":true,"unit":"wwatt-000042#insight-3","date_modified":"2026-10-23"},{"text":"The flooding's impact was exacerbated by urban vulnerability and exposure, including unplanned growth, the presence of approximately 150,000 illegal buildings, encroachment of drainage channels, and a lack of timely desilting and flood zone planning.","ai_generated":true,"unit":"wwatt-000042#insight-4","date_modified":"2026-10-23"}],"climate_tags":["flood","greenhouse gas","aerosol","sea surface temperature","El Niño southern oscillation","land-use planning","extreme event attribution"],"geography_discussed":["Bay of Bengal","Indian Ocean"],"frame_perspective":[],"analysis_type":["extreme event attribution"]},{"id":"wwatt-000122","url":"https://climateinsightsdirectory.org/document/wwatt-000122","title":"Attribution of severe low rainfall in southern Madagascar, 2019-21","publisher":{"name":"World Weather Attribution","organization":"world-weather-attribution"},"document_type":"research paper","language":"en","date_published":null,"source_url":"https://www.worldweatherattribution.org/wp-content/uploads/ScientificReport_Madagascar.pdf","generator":"Climate Insights Directory","generated_fields":["summary","key_insights","climate_tags","geography_discussed","analysis_type"],"summary":{"text":"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.","ai_generated":true,"unit":"wwatt-000122#summary","date_modified":"2026-10-23"},"key_insights":[{"text":"The rainfall deficit in the Grand Sud region from July 2019 to June 2021 was an exceptional event, with the rainy seasons of 2019/20 and 2020/21 receiving only 60% of normal rainfall.","ai_generated":true,"unit":"wwatt-000122#insight-1","date_modified":"2026-10-23"},{"text":"The 24-month period of low rainfall from July 2019 to June 2021 is estimated as a 1-in-135 year dry event, surpassed in severity only by the drought of 1990-92.","ai_generated":true,"unit":"wwatt-000122#insight-2","date_modified":"2026-10-23"},{"text":"Human-caused climate change did not significantly increase the occurrence of the poor rains observed between July 2019 and June 2021, as trends are currently overwhelmed by natural variability.","ai_generated":true,"unit":"wwatt-000122#insight-3","date_modified":"2026-10-23"},{"text":"Large-scale teleconnections, including El Niño and La Niña, did not significantly alter the likelihood of these rainfall deficits; for example, the 2020/21 season was exceptionally dry despite a moderate La Niña event.","ai_generated":true,"unit":"wwatt-000122#insight-4","date_modified":"2026-10-23"},{"text":"The synthesis of observations and models shows a non-significant probability ratio of 1.36 and a non-significant change in total rainfall intensity of -2.1% when comparing the current climate to a pre-industrial climate 1.2°C cooler.","ai_generated":true,"unit":"wwatt-000122#insight-5","date_modified":"2026-10-23"},{"text":"The food security crisis was exacerbated by extreme socio-economic vulnerability, with 91% of the population in the Grand Sud region living below the poverty line.","ai_generated":true,"unit":"wwatt-000122#insight-6","date_modified":"2026-10-23"},{"text":"The COVID-19 pandemic acted as a risk multiplier by restricting movement and reducing income-earning opportunities for daily wage laborers who typically migrate for work during poor yield years.","ai_generated":true,"unit":"wwatt-000122#insight-7","date_modified":"2026-10-23"},{"text":"Other compounding factors contributing to the food crisis included pest infestations, specifically migratory locusts and Fall Armyworm, as well as poor water and road infrastructure.","ai_generated":true,"unit":"wwatt-000122#insight-8","date_modified":"2026-10-23"},{"text":"The findings are consistent with the IPCC's Sixth Assessment Report, which suggests that perceptible changes in drought in this region may only emerge if global mean temperatures exceed 2°C above pre-industrial levels.","ai_generated":true,"unit":"wwatt-000122#insight-9","date_modified":"2026-10-23"}],"climate_tags":["food security","anthropogenic climate change","El Niño southern oscillation","extreme event attribution"],"geography_discussed":["Androy","Atsimo-Andrefana","Anôsy","East Africa"],"frame_perspective":[],"analysis_type":["extreme event attribution","observational analysis","climate modeling"]}]}