Broadkill - Courtesy Delaware Geological Survey

Delaware Climate Impacts - How Climate Affects You

Changes in temperature, rainfall, and sea levels are already being observed across the state. These changes are expected to continue and become even more serious in the coming years. Based on findings of a 2014 study conducted by Delaware’s Department of Natural Resources and Environmental Control (DNREC) we expect:

1.    Average temperatures to increase

  • Annual and seasonal temperatures in Delaware have already increased by 2 degrees Fahrenheit since 1900.
  • Average temperatures are expected to increase another 2.5 to 4.5 degrees by 2050 (mid-century) and by as much as 8 degrees by 2100 (late-century).

2.    Temperature extremes to become more frequent

  • Higher summer temperatures (days over 95 degrees Fahrenheit) and longer growing seasons already are being recorded.
  • The number of very hot days (over 95 degrees Fahrenheit) is expected to increase.
  • Heat waves are projected to become longer and more frequent.

3.    More frequent extreme rainfall

  • Average precipitation is expected to increase by about 10 percent by 2100 (late century).
  • Heavy rainstorms are expected to become more frequent and more intense, with an increasing number of very wet days with 2 inches or more of rainfall.

Video: "Climate Change in Delaware" produced by DNREC

Scientific facts and figures are important to understanding how climate is changing across the globe, but for local decision makers it is critical to understand how climate is changing in Delaware.  At an individual level, it is equally important to recognize how future climate will affect you - your home and health, your water and food, and your community and state as a whole.

The impact of climate change on human health can be very serious, and effects can be most critical for at-risk populations such as infants, children, and seniors. Increasing temperatures may raise the risk of serious illness such as heat stroke, heart disease, and asthma.  The combination of higher temperatures and more frequent rainfall could increase exposure to allergens and tick-and mosquito-borne diseases. Changes in precipitation events can also have consequences for local agriculture and food supply.

Delaware’s businesses, industries and economies rely heavily on roads and associated infrastructure. Bridges and roads will be more susceptible to damage because of more severe storms and heavy rainfall, resulting in possible impacts to evacuation routes. Sea-level rise and increased storminess may threaten public and private property at the coast, with increased risk of flooding and loss of waterfront land. Increased flooding could also affect inland areas, structures, and facilities.

Delaware’s Climate Change Impact Assessment

In 2014, Delaware’s Department of Natural Resources and Environmental Control (DNREC) completed a multi-year study and comprehensive report: Delaware Climate Change Impact Assessment. This report summarizes the best available science specific to Delaware, and explains how climate change may affect Delaware’s people, places, and resources.  A general overview a general summary of this report is included below.

Public Health

Increasing temperatures

  1. Increasing temperatures have direct and serious impacts on human health, particularly for vulnerable populations: elderly or very young people, those with underlying health conditions such as asthma or heart disease, and socially isolated individuals with limited access to air conditioning or health care.
  2. Increasing temperatures may worsen air quality, exacerbating conditions that produce ground-level ozone.

Changes in precipitation: increasing extreme rain

  1. Flooding may stress the capacity of stormwater and wastewater outfalls, causing water to back up and transporting polluted waters to upland areas. Increasing precipitation and sea level rise may lead to failure of septic drain fields as groundwater levels rise.
  2. Increasing precipitation and temperatures may lead to conditions that increase exposure to allergens, as well as to pathogenic diseases.

Water Resources

Increasing temperatures

  1. Water supply and demand will be affected by rising temperatures and longer periods of dry days, especially in summer months.

Changes in precipitation: increasing dry days

  1. Salinity increases upstream in coastal rivers and streams during periods of drought, when freshwater inflow decreases. This effect may be magnified with increasing frequency and duration of seasonal droughts, and may be further exacerbated with sea level rise.

Changes in precipitation: increasing extreme rain

  1. Sewer and stormwater systems will be increasingly strained to manage peak flows that may exceed their design specifications.
  2. Increased flooding associated with extreme rain events may result in structural or operational damage to dams, levees, impoundments and drainage ditches.

Sea level rise

  1. Salinity in tidal reaches of rivers and streams may be affected by climate change impacts. Sea level rise could increase the tidal influence and salinity levels upriver, although increased precipitation could offset the increasing salinity with additional freshwater flow.


Increasing temperatures

  1. Heat stress resulting from extreme heat days or sustained heat waves can have significant impacts for poultry and other livestock. Hotter summers lead to greater heat stress on animal health and   reduced feed and growth efficiency, and may require increased energy usage for ventilation and cooling in livestock barns and poultry houses.
  2. A longer growing season and warmer winter temperatures may provide some benefits for crop production. However, warmer winter temperatures may result in increased competition from weed species and insect pests.

Changes in precipitation: increasing dry days

  1. Rising temperatures and increased frequency of drought may lead to crop losses, reduced yields, impaired pollination and seed development, and higher infrastructure and energy costs to meet irrigation needs.
  2. Heat, drought, and extreme weather may affect the dairy industry by reducing forage supply and quality, which accounts for more than half of the feed requirements for dairy cows.

Changes in precipitation: increasing extreme rain

  1. Extreme rain events can affect infrastructure and systems that are critical to agriculture. Flooding can impair transportation of crops or livestock to markets or processing facilities, prevent deliveries of feed, or damage processing facilities for poultry and other livestock.
  2. Rain events of increasing frequency and intensity will have significant impacts at critical periods in crop production, such as delayed planting or post-planting washouts and increases in disease pressure.

Sea level rise

  1. Sea level rise may affect soil and groundwater quality in coastal regions and along tidal reaches of streams and rivers.

Ecosystems and Wildlife

Increasing temperatures

  • Many of Delaware’s wildlife species will face changes in habitat quality, timing and availability of food sources, abundance of pests and diseases, and other stressors related to changes in temperature and precipitation.
  • Increased temperatures and more frequent droughts will stress freshwater habitats, including streams, rivers, and ponds. Higher water temperatures are likely to increase the incidence of harmful algal blooms, which affect the availability of oxygen and light for aquatic species. Extreme decreases in oxygen levels may lead to more frequent fish kills.

Changes in precipitation: increasing dry days

  1. Increasing dry days combined with increased air temperatures may lead to higher evapotranspiration and decreased soil moisture. These factors are likely to contribute to plant stress, resulting in decreased productivity and greater susceptibility to pests and diseases.

Changes in precipitation: increasing extreme rain

  1. Tidal flooding is likely to increase from both sea level rise and potential increases in heavy rain events. Tidal wetlands will be affected by greater storm surges, scouring of tidal creeks and channels, and greater swings in salinity.

Sea level rise

  1. Coastal ecosystems are already vulnerable to coastal storms; the combined effects of sea level rise and extreme rain events may lead to increased erosion and loss of beach habitat.


Increasing temperatures

  1. Under heat wave conditions, peak demands for electricity in summer months increase dramatically and vulnerability to power outages can affect wide regions.
  2. Increased heat can accelerate deterioration of infrastructure, such as heat stress in structural supports and exposure of pavement to high heat. Buckling or rutting of asphalt may occur on roads or runways. These impacts may require increased maintenance and more frequent monitoring to prevent damage and ensure public safety.

Changes in precipitation: increasing dry days

  1. Drought conditions tend to push the salt line up the Delaware River; this increased salinity can affect the availability and function of cooling water needed for power generation and other industrial uses.

Changes in precipitation: increasing extreme rain

  1. With potential increases in precipitation falling in more intense storm events, the higher volume and velocity of surface runoff can result in rapid erosion and scouring. This can undermine structural supports for roads, bridges, culverts, and other drainage structures.
  2. Flooding impacts to road and rail lines also affect energy production, particularly for coal-fired power generation that relies on coal transport by rail.
  3. Changes in the timing of spring thaw and shifts in seasonal flows and water levels could increase flooding, particularly in urban areas of northern Delaware, where a high percentage of impervious surface area already contributes to severe stormwater runoff problems.

Sea level rise

  1. Sea level rise is likely to affect roads and bridges throughout the state. In Sussex and Kent Counties, many beach communities may be affected by sea level rise cutting off their primary access roads and evacuation routes. In New Castle County, Delaware City and portions of State Route 9 are also vulnerable to severe flooding from sea level rise.
  2. The Port of Wilmington is a major facility that could be significantly affected; an estimated 60 percent of the Port’s main facilities could be inundated by 3 feet of sea level rise.

 Visit the DNREC website to view this entire report.

Header image courtesy of Delaware Geological Survey

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Page Updated on March 7, 2016