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The report finds that record-breaking sea surface temperatures in July 2026 across European coasts were driven by human-induced climate change, with some regions experiencing warming that substantially exceeds global averages. These extreme temperatures have triggered marine heatwaves, species range shifts, and increased risks to human health and coastal infrastructure. The analysis indicates that such events would have been virtually impossible in a pre-industrial climate and will continue to intensify as global warming progresses.

Climate change accounted for 27% of the rate of heat-related emergency room visits in the U.S. during 2018-2025. August 2026 was the warmest August on record globally, with record warmth affecting 13.2% of global land and ocean areas. In the U.S., Summer 2026 was the warmest on record for the contiguous region, and August 2026 was the warmest August for average, maximum, and minimum temperatures since 1895. Drought affected at least 81% of the contiguous U.S. as of September 8, 2026, and nearly 8.3 million acres burned year-to-date, driven by increased 'fire weather' days. Attribution analysis using the Climate Shift Index (CSI) indicates human-caused climate change drove summertime warming trends in 91% of analyzed U.S. cities. Additionally, a strong El Niño event is projected to peak around February 2027, with global temperature anomalies potentially reaching 1.7C above pre-industrial levels.

The document argues that the 2022 Brisbane and 2022/23 Kimberley floods were made more likely and impactful by human-caused climate change, specifically through increased ocean temperatures, more frequent multi-year La Niña events, and higher atmospheric moisture. It concludes that while the frequency of some weather systems may decrease, the intensity of rainfall and flooding is expected to increase, potentially leading to prohibitive costs for protection and insurance in flood-prone zones.

A severe marine heat wave is impacting the northeast Pacific Ocean, with temperatures 2-5°F above normal and peak anomalies reaching 11°F. The event is strongly influenced by human-caused warming, which has increased the heat wave's footprint and duration.

The document describes El Niño as a natural climate phenomenon characterized by warmer-than-average sea surface temperatures in the equatorial Pacific. It argues that climate change is increasing the frequency and severity of extreme El Niño events, particularly Central-Pacific (CP) events, and complicating their prediction. For 2026, there is a 61% chance of an El Niño emerging between May and July, with some models suggesting it could be the strongest in 140 years. The briefing details global teleconnections, noting that El Niño typically causes droughts in southern Africa, Australia, and India, while increasing flood risks in East Africa and the Americas. These shifts significantly impact global agriculture, reducing yields for maize, rice, and wheat while often increasing soybean yields. Regional analysis highlights specific risks, such as increased cholera in East Africa, hydropower reductions at Kariba Dam in Zambia and Zimbabwe, and the Amazon becoming a net carbon source during Eastern-Pacific (EP) events.

April 2026 was the fourth-warmest month globally on record, with the contiguous U.S. experiencing its third-warmest April. The report highlights severe drought in the Southeast U.S., record-low Western snowpack, and a persistent marine heat wave off the coasts of California and Mexico. Using the Climate Shift Index (CSI), the analysis attributes springtime warming trends in 98% of analyzed U.S. cities to human-caused climate change, with exceptional warmth noted in Honolulu and San Juan. Forecasts indicate a high probability of a strong El Niño developing later in 2026, potentially driving global temperature anomalies above 1.8°C relative to pre-industrial levels by early 2027.

A World Weather Attribution study examines the role of climate change and natural variability in the devastating floods of November 2025 across Sri Lanka and the Malacca Strait. While observational data indicate a significant increase in the intensity of extreme 5-day rainfall events—up to 160% in Sri Lanka and 50% in the Malacca Strait due to a 1.3°C rise in global temperatures—climate models failed to consistently capture these trends, preventing a definitive quantitative attribution. The study also notes that La Niña and a negative Indian Ocean Dipole contributed between 5% and 13% to the rainfall in the Malacca Strait, while rapid urbanization and infrastructure failures exacerbated the humanitarian impact.

The document introduces attribution science as a method to measure how human-caused climate change affects the likelihood, frequency, and intensity of weather events by comparing current observations with simulated 'counterfactual' worlds. It details Climate Central's specific tools, such as the Climate Shift Index (CSI) for air and sea surface temperatures and the Tropical Cyclone CSI for hurricane wind speeds. The guide distinguishes between different types of attribution—event, trend, source, and impact—and notes that while temperature-related events are highly quantifiable, other severe weather like tornadoes remains an active area of research.

Hurricane Melissa, a Category 5 storm, caused widespread destruction and 61 deaths across Jamaica, Haiti, and the Dominican Republic in October 2025. Analysis indicates that climate change increased the likelihood of the extreme conditions that fueled the storm by a factor of about 6 and increased the intensity of associated rainfall by more than 9%. In Jamaica, 5-day rainfall events are now about 30% more intense and twice as likely, while in eastern Cuba, intensity increased by 50% and frequency by a factor of 9. The storm's maximum wind speeds are estimated to be approximately 7% more intense due to warming. Despite financial risk strategies like catastrophe bonds, damages in Jamaica are estimated to be at least an order of magnitude larger than available finance.

The October 2025 briefing reports that global temperatures remained exceptionally high, with the month ranking as the third warmest on record. In the U.S., warming fall temperatures have delayed the first freeze in 88% of analyzed cities, while significant drought persists across 67% of the contiguous U.S. despite localized heavy rainfall in Southern California.

Climate Central analysis finds that human-caused global warming increased the maximum wind speeds of every Atlantic hurricane in 2024 by 3 to 14 mph. This intensification was driven by record-breaking sea surface temperatures, which were made up to 800 times more likely by climate change. The report specifically highlights that major hurricanes Helene and Milton were strengthened by 10 mph and 8 mph respectively, and that three hurricanes were pushed into higher Saffir-Simpson categories due to this warming.

An event attribution study found that human-induced climate change increased the likelihood of the April 2025 extreme rainfall in the Central Mississippi river valley by approximately 40% and its intensity by 9%, though observational data suggests these increases could be as high as a factor of 2 to 5 in likelihood and 13-26% in intensity. The event caused at least 24 fatalities and estimated economic damages between $80 and $90 billion, with significant agricultural losses in Arkansas. The study highlights that while climate change amplified the event, effective early warnings from the US National Weather Service prevented a larger catastrophe, despite current staffing shortages in NWS field offices.

A marine heatwave has affected the west coast of Australia since September 2024, with over 60% of the analyzed region meeting heatwave criteria by early January 2025. The most affected area is off the northwest coast, where temperature anomalies exceeded 1.5 degrees Celsius and some locations remained in a heatwave state for over 120 days. Analysis using the Ocean Climate Shift Index indicates that climate change made these daily ocean surface temperatures at least 20 times more likely on average, with likelihood increasing over 100 times during late November.

The study identifies coastal upwelling events in the western San Matías Gulf, Argentina, noting approximately six upwelling-favorable wind events per year during the austral summer. Satellite sea surface temperature (SST) data confirmed upwelling in 85% of cases between 2000 and 2008, with specific events showing cold water bands approximately 10 km wide and 100 km long. In-situ data indicates that along-shore wind stress is the dominant process controlling high-frequency near-shore temperature fluctuations.

Analysis of the CARIACO station (1996–2013) reveals a significant increase in sea surface temperature, a decrease in pH, and a decline in chlorophyll a and phytoplankton abundance, alongside a reduction in upwelling intensity linked to lower wind speeds.

The study identifies a significant decrease in wind speed and a reduction in coastal upwelling days at Monte Hermoso between 2008 and 2015, coinciding with the absence of the medusa Olindias sambaquiensis. It also notes a 0.4 °C increasing trend in sea surface temperatures over the eight-year period, suggesting these environmental changes contribute to the lower occurrence of the species.

The document details the decline of the yellow clam (Mesodesma mactroides) along the Atlantic coast of South America due to rising sea surface temperatures and the subsequent recovery efforts in Uruguay. It highlights the use of co-management, conservative catch quotas, and phytoplankton monitoring as adaptive measures to build fishery resilience against climate stressors and harmful algal blooms.

The study identifies divergent sea surface temperature trends around southern South America between 1982 and 2017, with warming in mid-latitude regions and the Northern Patagonian Shelf, and cooling south of 50°S and on the Southern Patagonian Shelf. These trends became most significant between 2008 and 2017 and are linked to atmospheric forcing and large-scale climate modes including ENSO, the Interdecadal Pacific Oscillation, and the Southern Annular Mode.

Climate Central's Ocean CSI analysis indicates that Cyclone Chido intensified over waters made significantly warmer by human-caused climate change, with some temperature spikes being up to 92 times more likely due to global warming.

Climate change increased the maximum wind speeds of every Atlantic hurricane in 2024 by 3 to 14 mph, with some storms moving into higher Saffir-Simpson categories. The analysis, based on a rapid attribution framework, found that human-caused global warming elevated ocean temperatures by as much as 2.5°F, making elevated sea surface temperatures in hurricane tracks up to 800 times more likely.