Climate Change Glossary

The earth on a field of grass

The steps we must take to lessen the harmful impacts of climate change on both human and natural systems. These steps can make us less vulnerable to changes that already have occurred (such as rebuilding levees in hurricane-prone regions) and help us cope with future risks (such as switching to drought-resistant crops). They also include the planned management actions that federal, state and local governments will take to help reduce the impacts of climate change on fish, wildlife and their habitats through the strategic conservation of terrestrial, freshwater and marine habitats within sustainable landscapes.


Refers to surplus greenhouse gas emission reductions and removals that are additional to what would have occurred in the absence of the project (i.e. “business as usual”).


Lowlands along streams and rivers, usually on alluvial floodplains that periodically are flooded. Establishing forest cover on these lands is an important step in ecosystem restoration. Healthy bottomland systems are important for carbon sequestration as well as providing valuable wildlife habitat, reducing soil erosion, improving water quality and preventing flooding in these low-lying areas.

Cap and trade:

A market-based system to reduce greenhouse gas emissions. Under a cap-and-trade program, a government agency sets a total limit or “cap” on the amount of emissions that can be produced by a group of facilities or businesses. Each member of the group receives or purchases, dependent upon the system structure, the right to emit a certain portion of the cap, and these rights can be traded or sold to other group members. In this way, governments can limit emissions while giving businesses the flexibility and financial incentive to decide how to meet the cap’s requirements.


The weather of a particular region, averaged over decades or even hundreds of years. Climate also includes the pattern of rainfall and cold and warm seasons in an area. Global climate is measured by averaging climate trends across all regions of the Earth. The global climate is undoubtedly warming; Scientists forecast that by 2100 global average temperatures may rise between 2 and 11.5 degree Fahrenheit by the year 2100.

Core areas:

The most important areas in the current range a plant or animal to help ensure its long-term survival. Core areas usually are chosen for protection because they contain large populations of a given species; important breeding, hatching and/or feeding areas; and may connect populations across a wider region. Climate change is shrinking the core areas for some species; other core areas are expanding.

Ecosystem services:

Services provided to a community by its surrounding ecosystem. Some examples of ecosystem services are freshwater filtration and protection, safeguarding against fire and flood, production of agriculture, and habitat for wildlife that allows for pollination and hunting by the local community, among other items. As ecosystems are altered by climate change, these services may be threatened or disappear entirely.


The fracturing of a species’ habitat into smaller, disconnected areas. Fragmentation can fuel plant and animal extinctions by reducing the total amount of habitat, creating habitat “edges” that are vulnerable to fires and invasive species, and splitting species into smaller and less genetically healthy populations. Ongoing climate change and activities such as farming, logging and development are the main causes of fragmentation.

Greenhouse gas:

Gases in the Earth’s atmosphere that trap heat, including carbon dioxide, methane, nitrous oxide and others. Greenhouse gases are a natural part of the atmosphere, but human activities such as the burning of coal and oil have increased the concentration of these gases significantly. Burning of fossil fuels to create energy is the primary source of the greenhouse gases and the main cause of global warming.


Occurs when emissions avoided at a project site are displaced to another site. For example, if a forest preserved in one location causes trees to be cut down somewhere else.


Connections between entire ecosystems across a region over time; linkages allow species to move gradually between larger landscapes over a period of generations. Linkages may not always be geographical pathways, such as wildlife corridors. Instead, they could be links formed by an ecosystem’s food web—what eats what—and similar connections. Linkages are one of the best ways for plants and small animals affected by climate change to find new habitats.

Migration routes:

The routes followed by animals as they move between winter and summer feeding areas, or breeding and hatching areas. Climate change can shrink or sever migration corridors, shift the latitude of the routes, disrupt the timing of migrations, and in some cases crowd the routes as more species migrate away from habitats altered by warming.


The steps we must take to reduce the pace and size of climate change caused by greenhouse gas emissions. Mitigation policies and technology could either reduce emissions (by using energy alternatives to oil and gas, for example) or find new ways to store emissions so that they do not pollute our atmosphere (by planting new trees to act as emission “sinks,” for example); the World Bank calls mitigation “avoiding the unmanageable.”

Carbon offset:

A carbon offset is an investment in a project or activity that reduces greenhouse gas emissions to the atmosphere or sequesters carbon from the atmosphere in addition to what would have occurred without the project. Carbon offsets are used to compensate for greenhouse gas emissions from one’s own activities.

Range shifts:

Range is the geographical area in which a particular species can be found. Range shifts are one of the most dramatic effects of climate change. Changing temperatures force species to seek out new areas with more favorable temperatures, rainfall, food and shelter. About 40% of wild plants and animals being studied are relocating as a result of climate change, often bringing them closer to roads and towns.


The ability of an ecosystem or species to remain whole and functioning as it copes with stress. Species that adapt to climate change by shifting their ranges are resilient, but resiliency also describes nations and local communities that successfully use new technologies and policies to lessen the disruptive impacts of warming.

Sea level rise:

Melting glaciers, ice caps and polar ice sheets, along with expansion of ocean waters due to heating, have raised the global average sea level at an average rate of 0.12 inches (3.1 millimeters) per year since 2003. Rising sea levels are already threatening wetlands, eroding beaches, overwhelming freshwater fisheries, and endangering coastal lives and property in the United States.

Wildlife corridors:

Areas that provide connectivity of habitat or potential habitat and that facilitate the ability of fish, wildlife and plants to move within a landscape as needed, either seasonally or longer-term. Human activities, such as building a highway or a housing development or logging, may restrict or disrupt wildlife corridors. Climate change is also expected to affect corridors. Identifying and protecting these corridors can preserve a species as its habitat and range shift as a result of changing climate and expanding human development.


The area that is of higher elevation, such as the prairie that surrounds a wetland, the mountain headwater region of a river basin, or the land next to a coastline. Uplands are usually thought to be less vulnerable to climate change than coasts or wetlands. They provide critical wildlife corridors, breeding areas and services such as freshwater filtering to adjacent lowland areas.