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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 report analyzes severe May 2016 rainstorms in Europe, finding that climate change significantly increased the probability of extreme 3-day rainfall in France's Seine and Loire basins, while results for southern Germany remained inconclusive.

The analysis found that while human-induced climate change slightly increased the probability of the 2016 record-breaking heat in Rajasthan, the effect was not statistically significant. The study suggests that the warming effect of greenhouse gases in India is being partially offset by the cooling effects of aerosols and increased irrigation. Despite the lack of a strong temperature trend, the combination of high heat, pollution, and humidity is increasing the health risks and mortality associated with heat waves.

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 analysis estimates that the 2015 global temperature anomaly was 1.05ºC above the 1850–1900 pre-industrial average. This warming is primarily attributed to anthropogenic forcing, with smaller contributions from El Niño and solar activity. The year 2015 is identified as likely the first to cross both the 1ºC temperature anomaly and the 400 ppm CO2 thresholds.

The study investigates the 2014/15 drought in southeast Brazil, specifically focusing on the impacts in São Paulo. Using a multi-method approach including historical observations and climate model simulations, the researchers found limited evidence that human-induced greenhouse gas emissions increased the hydrometeorological hazard. Instead, the severe impacts on water supply were primarily attributed to rapid population growth and increased water consumption.

The 2015 drought in north and central Ethiopia was an extremely rare event, estimated to occur once every few hundred years in the current climate. Analysis by World Weather Attribution indicates that a strong El Niño enhanced the drought, making it significantly drier during the Kiremt season. However, the study found no conclusive evidence that human-induced climate change influenced the event, as results from various climate models were inconsistent and spanned a range from the drought being less likely to more likely. Despite the severity of the event, which affected nearly 10 million people and caused significant crop and livestock losses, the impact was lower than droughts in 1973 and 1984, suggesting improved national resilience.

The document serves as a manual for journalists to avoid common errors when linking specific weather events to climate change. It details the methodology of 'event attribution studies'—which use climate models to compare the current world with a pre-industrial one—and provides specific guidance on reporting heatwaves, floods, tropical cyclones, heavy snowfall, droughts, and wildfires. The guide emphasizes that while climate change increases the probability and intensity of many extremes, it is rarely the sole cause, and local factors like land use and water management often play critical roles in turning a weather event into a disaster.

The report investigates the May 2022 extreme rainfall event in Eastern Northeast Brazil, which caused 133 deaths and displaced over 25,000 people. Observational analysis indicates that 7-day and 15-day rainfall events of this magnitude are exceptionally rare in the current climate, with return periods of approximately 1-in-500 and 1-in-1000 years, respectively. While climate models exhibited systematic errors in precipitation magnitudes for this specific event, the authors conclude that human-caused climate change is at least partially responsible for increasing the likelihood and intensity of such rainfall. The study further highlights that structural vulnerabilities, including unplanned urbanisation in low-income neighbourhoods and an infrastructure deficit, significantly exacerbated the disaster's impact.

The document explains the science of extreme event attribution, which calculates how climate change alters the probability and intensity of specific weather events. It provides a detailed breakdown of how climate change influences heatwaves, floods, tropical cyclones, blizzards, droughts, and wildfires, while cautioning journalists against three common errors: ignoring climate change, attributing events without evidence, or treating climate change as the sole cause. It emphasizes that while global trends are clear for some phenomena (like heatwaves), others (like blizzards) remain highly uncertain.

The document explains how 'Extreme Event Attribution' research determines the extent to which climate change makes specific weather events more likely or intense. It warns journalists against three common errors: ignoring climate change, attributing events without evidence, or naming it as the sole cause. The guide provides detailed scientific contexts for heatwaves, floods, tropical cyclones, heavy snowfall, droughts, and wildfires, noting that while some links (like heatwaves) are globally certain, others (like droughts or snowfall) are more complex and region-specific.

The document explains 'extreme event attribution'—the scientific method used to determine if and how much climate change influenced a specific weather event. It warns journalists against three common mistakes: ignoring climate change, attributing events without evidence, or citing it as the sole cause. The guide provides detailed analysis for heatwaves, floods, tropical cyclones, heavy snow, droughts, and fires, noting that while heatwaves are unilaterally linked to global warming, other events like droughts and snowfall have more complex, region-specific relationships with climate change. It emphasizes that disasters result from both extreme weather and societal vulnerability.

The document explains the methodology of 'extreme event attribution' to help journalists avoid common errors, such as ignoring climate change or attributing an event to it as a sole cause. It details how scientists use climate models to compare the modern world with a pre-industrial one to determine if an event was more likely or intense due to global warming. The guide provides specific scientific consensus and limitations for heatwaves, floods, tropical cyclones, heavy snowfall, droughts, and wildfires, emphasizing that while some connections are robust (e.g., heatwaves), others are more complex and depend on regional data and human vulnerability.

The document explains the science of extreme event attribution, detailing how researchers use climate models and historical data to determine if climate change made a specific event more likely or intense. It provides specific guidance on reporting various phenomena—heatwaves, floods, tropical cyclones, snowfall, droughts, and wildfires—highlighting where scientific confidence is high and where uncertainties remain.

The study finds that while overall spring minimum temperatures are increasing, human-caused warming has advanced the start of the growing season (bud burst), exposing plants to more intense frosts. The April 2021 event in central France is attributed in part to this shift, with models projecting an increase in the frequency of such growing-period frosts in a 2°C warmer climate.

The document serves as a style guide for journalists to avoid common errors when attributing extreme weather to climate change. It explains the methodology of event attribution studies—comparing simulated worlds with and without human influence—and provides specific guidance on reporting heatwaves, floods, tropical cyclones, heavy snowfall, droughts, and wildfires. The guide emphasizes that while climate change increases the probability and intensity of many events, it is rarely the sole cause, and social vulnerability often determines whether a weather event becomes a disaster.

The study concludes that human-induced climate change made the March-April 2022 heatwave in India and Pakistan approximately 30 times more likely and about 1
C hotter than in a pre-industrial climate. The event, defined as a 1-in-100-year occurrence in today's climate, caused at least 90 deaths, triggered glacial lake outburst floods in northern Pakistan, and led to significant wheat crop yield losses in India, prompting a wheat export ban. The researchers warn that at 2
C of global warming, such heatwaves will become an additional factor of 2-20 more likely and 0.5-1.5
C hotter. Vulnerability is highest among outdoor daily wage earners and urban poor in informal settlements, though the report notes that Heat Action Plans in India, now covering 130 cities, can effectively reduce mortality.

The document explains 'event attribution' science, which quantifies how climate change alters the probability and intensity of specific weather events. It provides a detailed breakdown of how climate change affects heatwaves, floods, tropical cyclones, heavy snowfall, droughts, and wildfires, while cautioning journalists against common errors such as treating climate change as the sole cause of a disaster or ignoring it entirely. It emphasizes that while some trends are globally consistent (e.g., heatwaves), others are regionally variable or complex (e.g., droughts and snowfall).

The study finds that the July 2019 heatwave in Western Europe was made significantly more likely and intense by human-induced climate change. In France and the Netherlands, the event would have been extremely improbable without human influence, with return periods exceeding 1,000 years. Across all analyzed locations, the heatwave was 1.5 to 3 °C hotter than it would have been in an unchanged climate. The analysis utilized a combination of observational data and eight climate model ensembles, noting that while models generally underestimate temperature trends and overestimate variability, they still simulate large probability changes.

The report attributes the 2022 West African floods to a combination of anthropogenic climate change, which significantly increased the likelihood and intensity of rainfall in the Lake Chad and Lower Niger basins, and systemic vulnerabilities including poor water management, rapid unplanned urbanization, and socioeconomic instability. In the Lake Chad region, climate change made the seasonal rainfall event approximately 80 times more likely and 20% more intense. In the Lower Niger basin, the 7-day maximum rainfall event became about twice as likely and 5% more intense. The human toll was exacerbated by the release of the Lagdo Dam in Cameroon and the proximity of settlements to floodplains.