Report outlines climate change risks, energy system impacts

A new federal report outlines how climate change worsens existing vulnerabilities in communities across the U.S., poses a threat to the rate of economic growth over this century and presents added risks to interconnected systems that are already exposed to a range of stressors.

The report also details how climate change could affect the electricity sector including a reduction in the efficiency of power generation. The impacts of extreme weather and climate change on energy systems will differ across the U.S., according to the report.

The report was released on Nov. 23 by the U.S. Global Change Research Program, which is a federal program mandated by Congress to coordinate federal research and investments in understanding the forces shaping the global environment, both human and natural, and their impacts on society.

The Fourth National Climate Assessment includes summary findings that represent a very high-level synthesis of the material in the underlying report.

The summary findings cover the following 12 areas:

  • Communities
  • Economy
  • Interconnected impacts
  • Actions to reduce risks
  • Water
  • Health
  • Indigenous peoples
  • Ecosystems and ecosystem services
  • Agriculture and food
  • Infrastructure
  • Oceans and coasts
  • Tourism and recreation


In terms of communities, the report said that climate change “creates new risks and exacerbates existing vulnerabilities in communities across the United States, presenting growing challenges to human health and safety, quality of life, and the rate of economic growth.”

The report said that the impacts of climate change are already being felt in communities across the country. “More frequent and intense extreme weather and climate-related events, as well as changes in average climate conditions, are expected to continue to damage infrastructure, ecosystems, and social systems that provide essential benefits to communities,” the U.S. Global Change Research Program said.

In addition, future climate change is expected to further disrupt many areas of life, the report noted, exacerbating existing challenges to prosperity posed by aging and deteriorating infrastructure, stressed ecosystems, and economic inequality.

Impacts within and across regions will not be distributed equally, according to the report. “People who are already vulnerable, including lower-income and other marginalized communities, have lower capacity to prepare for and cope with extreme weather and climate-related events and are expected to experience greater impacts.”


As for economic impacts, the report said that without substantial and sustained global mitigation and regional adaptation efforts, climate change is expected to cause growing losses to infrastructure and property in the U.S. and impede the rate of economic growth over this century.

“In the absence of significant global mitigation action and regional adaptation efforts, rising temperatures, sea level rise, and changes in extreme events are expected to increasingly disrupt and damage critical infrastructure and property, labor productivity, and the vitality of our communities,” the U.S. Global Change Research Program said.

Regional economies and industries that depend on natural resources and favorable climate conditions, such as agriculture, tourism, and fisheries, are vulnerable to the growing impacts of climate change.

And rising temperatures are projected to reduce the efficiency of power generation while increasing energy demands, resulting in higher electricity costs.

Impact on water is another area that could affect generation

The quality and quantity of water available for use by people and ecosystems across the country are being affected by climate change, increasing risks and costs to agriculture, energy production, industry, recreation, and the environment, the U.S. Global Change Research Program said in the report.

It said that changes in the relative amounts and timing of snow and rainfall are leading to mismatches between water availability and needs in some regions, posing threats to, for example, the future reliability of hydropower production in the Southwest and the Northwest.

The report said that most U.S. power plants rely on a steady supply of water for cooling “and operations are expected to be affected by changes in water availability and temperature increases.”

Interconnected impacts

Climate change also presents added risks to interconnected systems that are already exposed to a range of stressors such as aging and deteriorating infrastructure, land-use changes, and population growth, according to the report.

“Extreme weather and climate-related impacts on one system can result in increased risks or failures in other critical systems, including water resources, food production and distribution, energy and transportation, public health, international trade, and national security.”

The report said that the full extent of climate change risks to interconnected systems, many of which span regional and national boundaries, is often greater than the sum of risks to individual sectors.

Failure to anticipate interconnected impacts can lead to missed opportunities for effectively managing the risks of climate change and can also lead to management responses that increase risks to other sectors and regions. Joint planning with stakeholders across sectors, regions, and jurisdictions can help identify critical risks arising from interaction among systems ahead of time.

Report includes section on energy supply, delivery and demand

The report, which includes a section that addresses energy supply, delivery and demand, said that the nation’s energy system “is already affected by extreme weather events, and due to climate change, it is projected to be increasingly threatened by more frequent and longer-lasting power outages affecting critical energy infrastructure and creating fuel availability and demand imbalances.”

The reliability, security, and resilience of the energy system underpin virtually every sector of the U.S. economy and cascading impacts on other critical sectors could affect economic and national security, the report went on to say.

The report said that changes in energy technologies, markets, and policies are affecting the energy system’s vulnerabilities to climate change and extreme weather. Some of these changes increase reliability and resilience, while others create additional vulnerabilities, according to the U.S. Global Change Research Program.

Changes include the following: (1) Natural gas is increasingly used as fuel for power plants; (2) Renewable resources are becoming increasingly cost competitive with an expanding market share; and (3) a resilient energy supply is increasingly important as telecommunications, transportation, and other critical systems are more interconnected than ever. 

Impacts on energy systems will differ across the U.S.

The impacts of extreme weather and climate change on energy systems will differ across the U.S., according to the report.

Low-lying energy facilities and systems located along inland waters or near the coasts are at elevated risk of flooding from more intense precipitation, rising sea levels, and more intense hurricanes. Increases in the severity and frequency of extreme precipitation are projected to affect inland energy infrastructure in every region.

Rising temperatures and extreme heat events are projected to reduce the generation capacity of thermoelectric power plants and decrease the efficiency of the transmission grid.

Rising temperatures are projected to also drive greater use of air conditioning and increase electricity demand, likely resulting in increases in electricity costs.

The increase in annual electricity demand across the country for cooling is offset only marginally by the relatively small decline in electricity demand for heating, according to the report.

“Extreme cold events, including ice and snow events, can damage power lines and impact fuel supplies. Severe drought, along with changes in evaporation, reductions in mountain snowpack, and shifting mountain snowmelt timing, is projected to reduce hydropower production and threaten oil and gas drilling and refining, as well as thermoelectric power plants that rely on surface water for cooling. Drier conditions are projected to increase the risk of wildfires and damage to energy production and generation assets and the power grid.”

The report said that it is possible to address the challenges of a changing climate and energy system, adding that both industry and governments at the local, state, regional, federal, and tribal levels are taking actions to improve the resilience of the energy system.

These actions include planning and operational measures that seek to anticipate climate impacts and prevent or respond to damages more effectively, as well as hardening measures to protect assets from damage during extreme events.

“Resilience actions can have co-benefits, such as developing and deploying new innovative energy technologies that increase resilience and reduce emissions. While steps are being taken, an escalation of the pace, scale, and scope of efforts is needed to ensure the safe and reliable provision of energy and to establish a climate-ready energy system to address present and future risks.”

Report outlines ways in which to reduce risks

The report also discusses ways in which to reduce risks through adaptation actions and emissions mitigation, but offers no policy recommendations.

With respect to adaptation, the report said that across the country, many regions and sectors are already experiencing the direct effects of climate change. Because climate impacts are expected to increase over time, communities “face the challenge not only of reducing greenhouse gas emissions, but also of adapting to current and future climate change to help mitigate climate risks.”

In general, adaptation can generate significant benefits in excess of its costs, according to the report. “Benefit–cost analysis can help guide organizations toward actions that most efficiently reduce risks, in particular those that, if not addressed, could prove extremely costly in the future.”

With respect to emissions mitigation, the U.S. Global Change Research Program said that many climate change impacts and associated economic damages in the U.S. can be substantially reduced over the course of the 21st century through global-scale reductions in greenhouse gas emissions, though the magnitude and timing of avoided risks vary by sector and region.

The effect of near-term emissions mitigation on reducing risks is expected to become apparent by mid-century and grow substantially thereafter, the report went on to say.

The full report is available here.