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Impacts

As the global average temperature continues to rise, impacts of climate change are expected to increase.  What impacts can we expect to see and where?  How might society and ecosystems adapt to these changes?

Ecosystems

Ecosystems will likely experience shifts in species ranges, an increase in wildfire number and extent, displacement of forest cover, and melting of permafrost due to warming.

The Loblolly Pine and Shortleaf Pine are two tree species typical of the southeastern United States.  As the climate warms, different tree species are projected to be suitable for this region and may start to displace the existing forest.

Adaptations
By connecting landscapes, we can support migration of native species in response to climate change.  Unfortunately, some tree species may not be able to migrate as fast as the climate may change.

Locations
United States, between Louisiana and South Carolina

Climate change can contribute to a species’ extinction, especially when the species does not have easy access to cooler areas where they can escape warm temperatures.  Access to cool refuges is particularly problematic for species, like the Akiapolaau bird or Black Robin, that are located on oceanic or mainland islands. 

Adaptation
Help species disperse to cooler refuges.  Without the aid of humans, these critically endangered species will go extinct.

Locations
Hawaiian Islands (Akiapolaau bird); Chatham Islands, off New Zealand’s coast (Black Robin)

 

Loss of Wetlands

A 1.6 ft (0.5 m) rise in worldwide sea level could destroy approximately 100,000 sq mi (250,000 sq km) of wetlands through coastal erosion. Wetlands are crucial habitats that have also been negatively affected by human development.

Adaptation
Create physical barriers to prevent ocean water from entering estuaries and wetlands. Allow wetlands to migrate inland and reduce diversions from coastal rivers.

Locations
Global along coasts

 

By 2050, the depth of permafrost thaws is projected to increase more than 50% in some regions. Thawing may lead to loss of infrastructure such as roads and homes. Furthermore, warming permafrost releases large amounts of methane, a powerful greenhouse gas, into the atmosphere.

Adaptation
Identify vulnerable areas and infrastructure. Where vulnerable, revise design criteria and standards for roads, bridge foundations, runways, and rail lines to reflect loss of permafrost.

Locations
Siberia, Northern Canada

 

In the western United States, the area burned by wildfire is estimated to increase by a factor of about 3 per 1.8°F (1°C) increase for the West, with some areas increasing by a factor of 7 or more.

Adaptation
Offer incentives to discourage building in wildfire-prone areas. Manage wildfires with controlled burns and fire suppression.

Locations
Western United States

 

Many species of mammals and birds will increasingly migrate up in elevation and towards the poles in response to climate change.  For example, in the early 20th Century, the America pika, a small mammal, could be found only in areas up to 7900 ft (2400 m) in elevation. In 2004, its habitat had shifted to as high as 9500 ft (2900 m).

Adaptation
Increase habitat availability and reduce stressors to capture the full geographical, geophysical, and ecological ranges of species on as many refuges as possible. Unfortunately, species may not be able to migrate as fast as the climate may change.

Locations
Mountains of western North America

 

Due to invasion of warm water species and high local extinction rates, marine species in the Arctic and Southern Ocean will continue to shift geographic ranges and many will die off.

Adaptation
Marine species are generally adapting by migrating down to deeper, cooler waters.

Locations
Arctic and Southern Oceans

 

Rising sea level could harm coastal wetlands and estuaries, coral reefs, and salt-marshes, which are important nursery habitats for larval and juvenile life-stages. These environments are already threatened by human actions.

Adaptation
Protect vital habitats with appropriate measures.

Locations
Global

 

Species are threatened by hunting, land-use change, and invasive species. Climate change, including loss of sea ice, is now another factor contributing to the possible extinction of many species, including the polar bear.

Adaptation
Enhance the strength and resilience of the species by protecting habitats, particularly in areas most affected by climate change.

Locations
Arctic

 

Maple, birch, and beech are tree species typical of the northeastern United States.  As the climate warms, different tree species are projected to be suitable for this region and may start to displace the existing forest.

Adaptation
By connecting landscapes, we can support migration of native species in response to climate change. Unfortunately, some tree species may not be able to migrate as fast as the climate may change.

Locations
Northeastern United States

 

The average thickness of Arctic sea ice has declined markedly over the past few decades. It is estimated that the thickness will further decrease by approximately 15% for every 1.8°F (1°C) of global warming. Arctic sea ice is vital for seals, polar bears, and walruses to hunt and rest.

Adaptation
It is uncertain whether animals that are dependent on sea ice habitats could adapt to a significant loss of sea ice.

Locations
Arctic

 

Temperature-related shifts in budding and breeding events have already been documented in the United States. These events are projected to occur even earlier in the season. If needed resources do not shift along with shifting species, earlier budding or breeding could cause a decline in breeding success.

Adaptation
Improve our understanding of the dynamics of social and ecological systems.

Locations
Global

 

The frequency of wildfires will continue to increase in many parts of the world.

Adaptation
Allow natural fires to burn where appropriate, thereby reducing wildfire fuel build-up. Manage wildfires with controlled burns and fire suppression.

Locations
Australia, New Zealand, the southern Mediterranean, most of Canada

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Food

Agriculture in some regions will likely benefit from better growing conditions under moderate climate change. However, agriculture production in many regions will likely be negatively affected by increases in heat, water stress, or weather extremes.


Many weeds, plant diseases, and insect pests benefit from warming (sometimes more than crops) and are therefore expected to expand their ranges as temperatures continue to rise. Weeds also benefit from elevated CO2 levels. Moreover, higher CO2 levels appear to make some herbicides less effective.

Adaptation
Apply integrated pest management practices to curb crop pest expansion. For example, develop pest-resistant crop varieties, use herbicides and pesticides, and maintain habitats for natural pest predators.

Locations
Global

 

Crops are adapted to specific climates.  When the climate warms too much, they come under stress from higher temperatures and/or increased drought, leading to shorter growing periods and lower yields.

Adaptation
Shift agriculture to different regions as the climate in those areas becomes more favorable for certain crops. Plant temperate crops earlier in the season.

Locations
Global

 

With global average warming of 3.6°F (2°C), catch potential could decrease by up to 40% in the tropics, as commercial species shift away from the warming waters there. Many of the complexities of marine ecosystems that affect fisheries are not well understood.

Adaptation
Put practices into place to sustain fisheries in a changing climate. Use adaptive management principles in natural resource management plans to reduce ecosystem vulnerabilities. Encourage alternative vocations in traditional fishing communities.

Locations
Tropics

 

Crop yields of U.S. corn, African corn, and Indian wheat are estimated to decrease by 5–15% for every 1.8°F (1°C) of global warming. U.S. corn crop losses are estimated to be roughly 25% for 3.6°F (2°C) of warming, all other things being equal.

Adaptation
Adjust sowing dates, change crop varieties, increase fertilization and irrigation, and develop new seeds that can better withstand water and heat stress and better utilize elevated CO2 levels.

Locations
Corn belt regions of the United States and Africa, wheat growing region of India

 

With global average warming of 3.6°F (2°C), catch potential could increase by 30–70% in high latitudes as commercial species shift away from the tropics due to ocean warming. Many of the complexities of marine ecosystems that affect fisheries are not well understood.

Adaptation
Put practices into place to sustain fisheries in a changing climate. Incorporate adaptive management principles in natural resource management plans to take advantage of fishery changes, while reducing ecosystem vulnerabilities.

Locations
High latitudes

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Ocean

Oceans will likely experience a decrease in marine productivity, an increase in ocean acidification, and an increase in the number of oxygen dead zones.


The average thickness of Arctic sea ice has declined markedly over the past few decades. It is estimated that the thickness will further decrease by approximately 15% for every 1.8°F (1°C) of global warming. Arctic sea ice is vital for seals, polar bears, and walruses to hunt and rest.

Adaptation
It is uncertain whether animals that are dependent on sea ice habitats could adapt to a significant loss of sea ice.

Locations
Arctic

 

As ocean water warms, ocean oxygen levels are likely to decline, exacerbating low-oxygen zones in coastal areas and deeper waters.  These dead zones degrade habitat and can lead to extensive fish and invertebrate mortality. 

Adaptation
Implement early warning and notification systems for events of coastal oxygen deprivation.

Locations
Brazil, India, Gulf Coast, Western Europe, China

 

With global average warming of 3.6°F (2°C), catch potential could decrease by up to 40% in the tropics, as commercial species shift away from the warming waters there. Many of the complexities of marine ecosystems that affect fisheries are not well understood.

Adaptation
Put practices into place to sustain fisheries in a changing climate. Use adaptive management principles in natural resource management plans to reduce ecosystem vulnerabilities. Encourage alternative vocations in traditional fishing communities.

Locations
Tropics

With global average warming of 3.6°F (2°C), catch potential could increase by 30–70% in high latitudes as commercial species shift away from the tropics due to ocean warming. Many of the complexities of marine ecosystems that affect fisheries are not well understood.

Adaptation
Put practices into place to sustain fisheries in a changing climate. Incorporate adaptive management principles in natural resource management plans to take advantage of fishery changes, while reducing ecosystem vulnerabilities.

Locations
High latitudes

 

Rising CO2 concentrations and ocean acidification reduce shell and skeleton growth in marine species such as corals and mollusks. Coral reefs will tend to erode rather than grow, harming the diverse forms of life that are reef-dependent.

Adaptation
Implement systems to evaluate and manage ecosystem impacts.

Locations
Global

 

Due to invasion of warm water species and high local extinction rates, marine species in the Arctic and Southern Ocean will continue to shift geographic ranges and many will die off.

Adaptation
Marine species are generally adapting by migrating down to deeper, cooler waters.

Locations
Arctic and Southern Oceans

 

Warming of the ocean surface is projected to decrease production of organic compounds in the oceans of the tropics and subtropics. This decreased production will reduce nutrient availability in surface waters.

Adaptation
Conduct evaluations and put systems into place to manage ecosystem impacts.

Locations
Western Atlantic Ocean off the coast of Great Britain, Black Sea

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Coasts

Coasts will likely experience a loss of coral reefs and, in some places, a loss of wetlands. Coastal infrastructure is expected to be increasingly impacted due to accelerated sea level rise.


A 1.6 ft (0.5 m) rise in worldwide sea level could destroy approximately 100,000 sq mi (250,000 sq km) of wetlands through coastal erosion. Wetlands are crucial habitats that have also been negatively affected by human development.

Adaptation
Create physical barriers to prevent ocean water from entering estuaries and wetlands. Allow wetlands to migrate inland and reduce diversions from coastal rivers.

Locations
Global along coasts

 

Rising sea levels can cause salt water to intrude into freshwater aquifers, contaminating groundwater with salt. This reduces freshwater supplies in coastal areas.

Adaptation
Restore or create coastal wetlands, barrier islands, and other natural or artificial barriers.

Locations
Coastal areas

 

Rising sea level could harm coastal wetlands and estuaries, coral reefs, and salt-marshes, which are important nursery habitats for larval and juvenile life-stages. These environments are already threatened by human actions.

Adaptation
Protect vital habitats with appropriate measures.

Locations
Global

 

Rising sea levels could destroy homes, roads, and other infrastructure in coastal areas through flooding and coastal erosion.

Adaptation
Eliminate public subsidies for future development in high hazard areas along the coast. Build sea walls to protect existing infrastructure. Design future public works projects to take into account rising sea levels.

Locations
Global

 

As ocean water warms, ocean oxygen levels are likely to decline, exacerbating low-oxygen zones in coastal areas and deeper waters. These dead zones degrade habitat and can lead to extensive fish and invertebrate mortality.

Adaptation
Implement early warning and notification systems for events of coastal oxygen deprivation.

Locations
Brazil, India, Gulf Coast, Western Europe, China

 

A rise in sea level of 1.6 ft (0.5 m) would increase the number of people annually at risk from coastal flooding by 5–200 million. As many as 4 million people could be permanently displaced.

Adaptation
Relocate people living along vulnerable coasts.

Locations
New York, Miami, Nile Delta, Ganges Delta, Mekong Delta

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Society

Society will likely experience shifts in the ranges of disease-carrying insects, changes in allergy seasons, changes in food harvests, impacts on coastal infrastructure, and displacement of populations living along coasts.


Rising sea levels can cause salt water to intrude into freshwater aquifers, contaminating groundwater with salt. This reduces freshwater supplies in coastal areas.

Adaptation
Restore or create coastal wetlands, barrier islands, and other natural or artificial barriers.

Locations
Coastal areas

 

Crop yields of U.S. corn, African corn, and Indian wheat are estimated to decrease by 5–15% for every 1.8°F (1°C) of global warming. U.S. corn crop losses are estimated to be roughly 25% for 3.6°F (2°C) of warming, all other things being equal.

Adaptation
Adjust sowing dates, change crop varieties, increase fertilization and irrigation, and develop new seeds that can better withstand water and heat stress and better utilize elevated CO2 levels.

Locations
Corn belt regions of the United States and Africa, wheat growing region of India

 

Warmer summers and more frequent and severe extreme heat events will likely increase worldwide demand for cooling energy, particularly for air conditioning. Winter demand for heating energy will tend to decrease.

Adaptation
Increase energy efficiency. Develop emerging technologies that adapt to changing energy availability and demand through the use of an integrated smart transmission grid.

Locations
Global, especially Southwestern United States

 

Climate change will shift the geographic range of insect-transmitted diseases like malaria and dengue fever by impacting the temperature, humidity, and rainfall that are optimal for mosquitoes and other vectors. Increases in some areas will likely be accompanied by decreases in others.

Adaptation
Employ preventive strategies to reduce or eliminate insect breeding grounds. Prevent the spread of disease by increasing the use of insect netting and using insecticides to reduce insect populations.

Locations
Global

 

Expanded Range of Crop Pests

Many weeds, plant diseases, and insect pests benefit from warming (sometimes more than crops) and are therefore expected to expand their ranges as temperatures continue to rise. Weeds also benefit from elevated CO2 levels. Moreover, higher CO2 levels appear to make some herbicides less effective.

Adaptation
Apply integrated pest management practices to curb crop pest expansion. For example, develop pest-resistant crop varieties, use herbicides and pesticides, and maintain habitats for natural pest predators.

Locations
Global

Shifts in growing seasons, mean temperatures, and atmospheric CO2 levels affect the length of the pollen season and alter the characteristics of plants. Some of these alterations may increase the pollen-producing capacity and toxicity of some species.

Adaptation
Follow medical advice, such as staying indoors and utilizing medications including antihistamines.

Locations
Global

 

Rising sea levels could destroy homes, roads, and other infrastructure in coastal areas through flooding and coastal erosion.

Adaptation
Eliminate public subsidies for future development in high hazard areas along the coast. Build sea walls to protect existing infrastructure. Design future public works projects to take into account rising sea levels.

Locations
Global

 

Challenges to meet water resource demands that face many western states will get worse as a result of global warming. For example, stream flow is expected to decrease by 5–10% for every 1.8°F (1°C) of warming.

Adaptation
Restructure existing reservoirs and conduct water transfers to adapt to changing needs. Enhance reservoir and aquifer storage capacity. Employ vegetation management to improve water storage and timing of watershed runoff. Encourage water conservation.

Locations
Arkansas and Rio Grande river basins

 

The frequency and severity of heat waves in Europe and North America are expected to increase.  It is estimated that with a 5.4°F (3°C) warming, 9 out of 10 summers will be warmer than all but about 1 of the 20 summers in the last decades of the 20th century.  These changes will increase the risk of heat-related illness and death.

Adaptation
Implement early warning systems and emergency response plans for heat waves. Improve building design to reduce heat loads during summer months. Develop urban design that reduces the urban heat island effect by planting trees and increasing green spaces.

Locations
Europe and North America

 

A rise in sea level of 1.6 ft (0.5 m) would increase the number of people annually at risk from coastal flooding by 5–200 million. As many as 4 million people could be permanently displaced.

Adaptation
Relocate people living along vulnerable coasts.

Locations
New York, Miami, Nile Delta, Ganges Delta, Mekong Delta

 

Warmer temperatures increase the production of ground level ozone, which affects respiratory health. The number of days with ozone pollution levels above the defined safety standard is projected to increase.

Adaptation
Design and implement warning systems that recommend those at higher risk stay indoors.

Locations
Densely populated areas in the United States, China, and elsewhere around the world with warm summers.

 

Decreasing sea ice in the Arctic could open the Northern Sea Route, making it easier to transport goods between Asia, North America, and Europe. New sea routes will introduce new geopolitical dilemmas and impact national security.

Adaptation
Engage in international dialogue and coordination regarding the newly-opened waterways.

Locations
Arctic

 

By 2050, the depth of permafrost thaws is projected to increase more than 50% in some regions. Thawing may lead to loss of infrastructure such as roads and homes. Furthermore, warming permafrost releases large amounts of methane, a powerful greenhouse gas, into the atmosphere.

Adaptation
Identify vulnerable areas and infrastructure. Where vulnerable, revise design criteria and standards for roads, bridge foundations, runways, and rail lines to reflect loss of permafrost.

Locations
Siberia, Northern Canada

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Weather

Weather patterns will change. For example, there will likely include be a higher frequency of heat waves. Many regions that are currently relatively dry will tend to become even drier.


The frequency and severity of heat waves in Europe and North America are expected to increase.  It is estimated that with a 5.4°F (3°C) warming, 9 out of 10 summers will be warmer than all but about 1 of the 20 summers in the last decades of the 20th century.  These changes will increase the risk of heat-related illness and death.

Adaptation
Implement early warning systems and emergency response plans for heat waves. Improve building design to reduce heat loads during summer months. Develop urban design that reduces the urban heat island effect by planting trees and increasing green spaces.

Locations
Europe and North America

 

Precipitation will tend to increase in northern regions of the United States. Rainfall in Alaska and other high-latitude areas in the Northern Hemisphere is expected to increase about 5–10% per 1.8°F (1°C) of warming. This increased precipitation could lead to flooding, erosion, and other problems. It is unclear how rainfall amounts will change over large parts of the United States, particularly during the summer.

Adaptation
Establish and implement systems to manage flooding, erosion, and nutrient leaching. Develop flood resistant crops.

Locations
Northern United States, Alaska

 

As the climate warms, atmospheric water vapor content increases, potentially leading to increases in heavy precipitation.  Heavy precipitation (defined as the heaviest 15% of daily rainfall) is likely to increase 3-10% for each 1.8°F (1°C) of warming.  Changes are likely to be greatest in tropical regions. Increases in heavy precipitation could lead to increased flooding. The science is still quite uncertain regarding where and by how much heavy precipitation events will change.

Adaptation
Protect vital infrastructure from flooding associated with extreme weather. Prevent new development in areas that cannot be adequately protected from flooding.

Locations
Global, especially the tropics

 

Rainfall in southwestern North America, the Mediterranean, and southern Africa is estimated to decrease about 5–10% for every 1.8°F (1°C) of warming. This will impact crop growth and drinking water availability. It is unclear how rainfall amounts will change over large parts of the United States, particularly in the summer.

Adaptation
Adopt irrigation practices that save water. Use technologies to harvest water and conserve soil moisture. Use water more conservatively in areas where aquifers are not being replenished.

Locations
Mediterranean, Southwestern North America, Southern Africa

 

The area affected by drought is likely to expand with changes in precipitation and soil moisture brought on by global climate change. Human activities like urbanization, deforestation, and agricultural practices also impact drought.

Adaptation
Reduce water demand by increasing efficiency of use. Manage for water-conserving species and store water to maintain adequate flows during droughts.

Locations
Global

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Disclaimer

These projected impacts and their associated locations serve as examples and are not meant to be comprehensive.  The examples are based on current understanding and projections of climate impacts.  Each impact discussed is representative of a particular climate zone.

Climate research tells us that, in some regions, we can expect increases in dramatic events, such as flooding, droughts, and severe storms, as the climate warms.  However, each dramatic event is influenced by the immediate weather conditions and in some cases by overall climate trends.  Therefore, scientists don’t say that a specific event is caused by climate change.  Rather, climate change makes some kinds of events in some regions more likely.