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Climate Change

Climate Change Indicators in the United States

The indicators in this report show that changes are occurring throughout the Earth's climate system, including increases in air and ocean temperatures, more extreme weather events, a rise in sea level, widespread melting of glaciers, and longer ice-free periods on lakes and rivers. Changes such as these can present a wide range of challenges to human well-being, the economy, and natural ecosystems.

What is happening?

For society, human health effects from increases in temperature are likely to include increases in heat-related illnesses and deaths, especially in urban areas. Changes in precipitation patterns and timing affect streamflow and water availability, while more severe storms and floods damage property and infrastructure (such as roads, bridges, and utilities) and cause loss of life. Warming temperatures are also affecting the length of the growing season in the United States as the timing between the last (spring) and first (fall) frost has expanded by nearly two weeks over the last 100 years.

Changes in climate can affect ecosystems by influencing animal behavior, such as nesting and migration patterns, as well as the timing and extent of natural processes such as flower blooms and the length of pollen seasons in many areas.

While species have adapted to environmental change for millions of years, climate change could require adaptation on larger and faster scales than current species have successfully achieved in the past.

Why does it matter?

Ecosystems provide humans with food, clean water, and a variety of other services that can be affected by climate change. While species have adapted to environmental change for millions of years, the climate changes being experienced now could require adaptation on larger and faster scales than current species have successfully achieved in the past, thus increasing the risk of extinction for some species.

The more the climate changes, the greater the potential effects on society and ecosystems. The nature and extent of climate change effects, and whether these effects will be harmful or beneficial, will vary regionally and over time. The extent to which climate change will affect different ecosystems, regions, and sectors of society will depend not only on the sensitivity of those systems to climate change, but also on their ability to adapt to or cope with climate change.

Climate Change Indicators and Human Health

This report provides several environmental and ecological indicators of observed change related to climate. Although climate change can affect human health in a number of direct and indirect ways, well-defined, consensus-based “health” indicators are limited.

In 2011, The Centers for Disease Control and Prevention (CDC) introduced a suite of indicators to track the effects of climate change on human health through the Environmental Public Health Tracking Network (EPHTN). The network links standardized metrics from local, state, and national databases on environmental hazards and human health effects with climate information. 1 EPHTN is an emerging effort from which useful indicators may be leveraged to track potential direct and indirect health effects due to climate change. For more information about EPHTN, go to: www.cdc.gov/nceh/tracking.

Many societal and environmental factors can influence how climate change will affect health in any given community. These factors include the extent, frequency, and severity of climate change impacts; the ability of communities to prepare for and respond to the risks posed by climate change; and the vulnerability of the different populations living in the community.

Because the impacts of climate change on health are complex, often indirect, and dependent on multiple societal and environmental factors, the development of appropriate climate-related health indicators is challenging and still emerging. To ensure that response measures are effective and adverse health effects are avoided, it is important for climate-related health indicators to be clear, measurable, timely, and closely linked to changes in climate. 2,3

Climate health indicators will be instrumental not only in tracking and measuring health impacts of climate change but also, more importantly, in identifying areas where the protection of public health is needed most. EPA plans to explore opportunities to work with climate and health experts to develop indicators that communicate the effects of climate change on health and society more broadly.

Key human health impacts and vulnerabilities associated with climate change include:

  • A warmer climate will increase the risk of heat-related illness and death. A warmer climate is also expected to decrease the risk of cold-related illness and death.
  • Climate change is expected to worsen conditions for air quality, including exposure to ground-level ozone, which can aggravate lung diseases and lead to premature death.
  • Climate change will likely increase the frequency and strength of certain extreme events (such as floods, droughts, and storms) that threaten human safety and health.
  • Changes in temperature and precipitation can spread or shift the geographic range of certain diseases and alter the seasons for pollen, affecting human exposure to infection, asthma, and other respiratory diseases.
  • Vulnerable populations including the poor, the elderly, those already in poor health, the disabled, and indigenous populations are most at risk.

For more information about climate change impacts and human health, visit EPA’s website: http://www.epa.gov/climatechange/impacts-adaptation/health.html.

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