National Climate Assessment report on the impacts of climate change

The United States is experiencing the impacts of climate change in every region, from fires in the west to hurricane-related flooding in the east. The National Climate Assessment (NCA) is a comprehensive and authoritative analysis of climate change impacts, risks, and responses in the United States.

Challenge

As mandated by Congress, the U.S. Global Change Research Program (USGCRP) develops and coordinates “a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.”

Comprising 14 federal agencies, USGCRP produces a comprehensive and authoritative report on climate change and its impacts on the nation every four years.

ICF helps the USGCRP manage the coordination between federal agencies, receive input from its Federal Advisory Committee, and coordinate more than a thousand experts, authors, and reviewers who contribute to the report. These types of collaboration don't happen naturally. The staff of the USGCRP, supported by ICF, are the glue that holds the process together. Our team of resilience, adaptation, and climate science experts serves as the navigation system, working in the background to help operationalize the work of the USGCRP.

A crucial piece of the NCA process is providing multiple opportunities for public input and feedback on the draft report. We collaborate with federal leads on the benefits and attributes of various choices. Once they've set their final priorities, we craft the public engagement process and implement the strategy to achieve their goals.

Released in November 2023, the 5th National Climate Assessment provides the scientific foundation on climate change impacts, risks, and responses. Key findings from the report:  

1. Risks from extreme events are increasing: The effects of human-caused climate change are already far-reaching and worsening across every region of the United States. One of the most direct ways that people experience climate change is through changes in extreme events. Harmful impacts from more frequent and severe extremes are increasing across the country—including increases in heat-related illnesses and death; costlier storm damages; longer droughts that reduce agricultural productivity and strain water systems; and larger, more severe wildfires that threaten homes and degrade air quality.

2. The cost of weather-related disasters has increased dramatically: Extreme events cost the U.S. close to $150 billion each year. Extreme weather events cause direct economic losses through infrastructure damage, disruptions in labor and public services, and losses in property values.

3. Climate change exacerbates inequities: Some communities are at higher risk of negative impacts from climate change due to social and economic inequities caused by ongoing systemic discrimination, exclusion, and under- or disinvestment. For example, low-income communities and communities of color often lack access to adequate flood infrastructure, green spaces, safe housing, and other resources that help protect people from climate impacts. In some areas, patterns of urban growth have led to the displacement of under-resourced communities to suburban and rural areas with less access to climate-ready housing and infrastructure. Extreme heat can lead to higher rates of illness and death in low-income neighborhoods, which are hotter on average.

4. Many harmful impacts will worsen: Many of the extreme events and harmful impacts that people are already experiencing will worsen as warming increases and new risks emerge.

• Safe, reliable water supplies are threatened by flooding, drought, and sea level rise.
• Disruptions to food systems are expected to increase.
• Homes and property are at risk from sea level rise and more intense extreme events.
• Infrastructure and services are increasingly damaged and disrupted by extreme weather and sea level rise.
• Climate change exacerbates existing health challenges and creates new ones.

5. Adaptation can help reduce rising climate risks: As more people face more severe climate impacts, individuals, organizations, companies, communities, and governments are taking advantage of adaptation opportunities that reduce risks. State climate assessments and online climate services portals are providing communities with location- and sector-specific information on climate hazards to support adaptation planning and implementation across the country. New tools, more data, advancements in social and behavioral sciences, and better consideration of practical experiences are facilitating a range of actions. Accelerating current efforts and implementing new ones that involve more fundamental shifts in systems and practices can help address current risks and prepare for future impacts.