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Climate Central's analysis of U.S. power outage data from 2000-2021 reveals a significant increase in large-scale disruptions, with 83% of major outages attributed to weather-related events. The report highlights that the frequency of major outages rose by 64% between 2011-2021 compared to 2000-2010, driven by severe weather, winter storms, hurricanes, extreme heat, and wildfires. It emphasizes the vulnerability of aging infrastructure and the compounding effects of climate change, which simultaneously increases electricity demand for cooling while reducing the capacity of power plants due to water shortages. The report identifies the Southeast as the region with the highest number of outages and notes specific recent surges in Texas, California, and Michigan.

The document examines how human-caused climate change and warming sea surface temperatures are increasing the proportion of intense tropical cyclones and the frequency of rapid intensification events. It highlights that tropical cyclones are the costliest weather disasters in the U.S., with 73% of billion-dollar storms since 1980 having undergone rapid intensification. The text notes that while landfalling hurricane frequency in the continental U.S. remained stable from 1900-2017, economic losses have risen due to increased population and wealth along the Gulf and East Coasts.

Since 1970, fall temperatures in the contiguous U.S. have increased by an average of 2.7 °F, with warming observed in 97% of 245 analyzed cities. The most significant warming occurred in Nevada, Texas, and Arizona, with Reno, Nevada, recording the highest increase at 7.7 °F. This trend has led to a higher frequency of above-normal fall days, affecting 74% of analyzed cities. These temperature shifts extend health risks from extreme heat, prolong pollen and wildfire seasons, allow disease-carrying insects to persist longer, and disrupt ecological events such as bird migrations and fruit ripening.

Harmful algal blooms (HABs) caused by cyanobacteria are increasing globally due to warming temperatures, heavier rainfall, and nutrient pollution. These blooms produce toxins that cause acute illnesses in humans, long-term organ damage, and death in wildlife. Mitigation requires reducing carbon emissions and nutrient runoff from agricultural and urban sources.

Climate Central analysis reveals that 83% of 241 analyzed U.S. cities saw an increase in summer stagnant days between 1973 and 2021, with a strong positive correlation between these events and rising summer high temperatures. Annual stagnation has also increased in 81% of these cities, with hotspots in Southern Texas and coastal California. These trends are expected to worsen with climate change, potentially adding up to 40 more stagnant days per year by late-century, which traps pollutants and disproportionately affects communities of color due to historical housing policies.

Since 1970, average summer nights in the contiguous U.S. have warmed by 2.5°F, with nighttime temperatures warming nearly twice as fast as daytime temperatures since 1895. Using the Climate Shift Index (CSI), Climate Central finds that climate change makes warm summer nights significantly more likely than warm days, posing health risks and increasing cooling costs.

A Climate Central analysis projects that by 2100, the average summer warming across 247 U.S. cities will be 8 °F, with many cities experiencing conditions currently found 437 miles to their south. For 16 cities, future summer temperatures will have no equivalent on the North American continent, instead mirroring conditions in Egypt and the Middle East. Specific projections for major cities include New York warming by 7.6 °F (similar to present-day Columbia, S.C.) and Chicago warming by 9.1 °F (similar to Montgomery, Ala.).

Analysis of 246 U.S. locations shows that 74% have experienced an annual increase in extremely hot days since 1970, with Austin, TX seeing the largest increase. The document highlights that extreme heat risks are higher in traditionally cooler regions due to lack of acclimatization and infrastructure, and that vulnerable populations including children, seniors, and low-income households are disproportionately affected.

The Climate Central Temperature Attribution System (CC-TAS) Version 1.0 operationalizes a multi-method framework to attribute temperature events to anthropogenic climate change. It utilizes two empirical methods (median-scaling and quantile-scaling) and a model-based method using CMIP6 simulations. To improve upon previous frameworks, CC-TAS incorporates high-resolution CFS reanalysis temperatures, ERA5 reanalysis for scale factors, and skew-normal parameterized distributions. The system introduces the 'occurrence ratio' (OR) as a primary metric to assess both warm and cold events, which is then converted into a conservative categorical 'Climate Shift Index' (CSI) for public mapping, primarily focusing on the contiguous United States.

The report analyzes the potential for U.S. coastal wetlands to either expand or almost entirely disappear by 2100 based on sea level rise rates, vertical accretion, and the conservation of land for horizontal migration. It identifies Louisiana, North Carolina, and Texas as high-risk areas and emphasizes that conserving undeveloped dryland (refugia) is a decisive factor in preventing widespread wetland loss.

The report analyzes the future of US coastal wetlands under various sea-level rise and development scenarios. It finds that wetlands can either expand by 25% or decrease by 97% by 2100, depending on human decisions regarding land conservation for migration and the rate of vertical growth. Louisiana, North Carolina, and Texas are identified as high-risk areas. The document emphasizes that preserving undeveloped land (refuges) is the most critical factor in preventing widespread wetland loss.

The document outlines how climate change impacts mental health through direct, indirect, and vicarious risks. It provides data on depression and PTSD following disasters like hurricanes, highlights widespread climate anxiety among Americans and global youth, and discusses strategies for building individual and community resilience.

The document reports that atmospheric carbon dioxide and methane levels continue to rise, with CO2 expected to break records in May 2022 and methane seeing its largest annual increase in 2021. It identifies the energy sector as the largest global emitter (34%) and the transportation sector as the largest U.S. emitter (27%), arguing that rapid and deep emission cuts across all sectors are necessary this decade to limit warming to 1.5C or below 2C.

An analysis of 150 U.S. weather stations shows that 90% experienced an increase in hourly rainfall intensity between 1970 and 2021, with an average increase of 13%. These intensifying rainfall extremes, which contribute to flash flooding and landslides, affect both wet and dry regions, with the most significant increases observed in locations such as Fairbanks, Alaska, and El Paso, Texas.

Climate Central's analysis of 150 U.S. weather stations shows that 90% experienced an increase in hourly rainfall intensity between 1970 and 2021, with an overall average increase of 13%. This trend is linked to the Clausius-Clapeyron equation, where warmer air holds more moisture, increasing the frequency and intensity of heavy downpours. Such extremes contribute significantly to flash flood risks, accounting for approximately one-third of U.S. flood damages ($73 billion) from 1988 to 2017. Future projections suggest that U.S. flash floods could intensify by 8% by 2100 under high-emission scenarios, with the Southwest and central U.S. identified as high-risk areas.

Between 1970 and 2021, growing degree days (GDD)—a measure of heat accumulation used to track plant and pest development—increased at 97% of 246 analyzed stations across the contiguous U.S. The average increase was 525 GDD, with the most significant rises occurring in the West, Southwest, and South. While some plants may benefit, increased GDD is linked to higher water and heat stress, altered agricultural schedules, and longer pollen seasons that exacerbate health issues like asthma and hay fever.

The report analyzes 2021 renewable energy generation in the continental U.S., estimating a total of 606,000 GWh from wind (73%) and solar (27%). It highlights Texas as the leader in raw wind generation and California in raw solar generation, while also examining generation normalized by land area and population. The document compares these figures against the Net Zero America Project's 2030 target of 2.2 million GWh per year, concluding that while current growth is accelerating, the U.S. needs to nearly double its annual increase in generation to stay on track for net-zero emissions by 2050.

Analysis of 19 Winter Olympic host cities shows an average February warming of 4.8 °F since 1950, with some cities like Oslo warming by 9.8 °F. A University of Waterloo study indicates that under a high-emissions scenario, only one host city (Sapporo) would reliably provide safe and fair outdoor snow sports conditions by the 2080s. The Paralympic Games face higher risks due to their typical March scheduling, which coincides with warmer temperatures and a higher probability of rain.

Between 1970 and 2021, 97% of 244 analyzed U.S. stations experienced shrinking winter cold snaps, with an average reduction of six days. The most significant decrease occurred in Las Vegas, Nevada, where cold snaps shortened by three weeks. These trends contribute to broader ecological and economic risks, including increased pest populations, reduced snowpack for water supplies, and threats to winter recreation and crop growth requiring winter chill.

The document reports that winter is the fastest warming season for most of the U.S., leading to a general decrease in fall and spring snowfall between 1970 and 2019. It details regional impacts, such as a 15-30% reduction in snow-derived freshwater in the Western U.S. since 1955, a shift toward rain over snow in the Northeast, and a shortened lake effect snow season in the Great Lakes region. These changes threaten water security for agriculture and municipalities, increase wildfire and drought risks, and negatively impact the winter recreation industry.