As Fairfax County moves forward with plans to address climate change and its impacts it is important to understand the basic scientific and social concepts behind climate conversations. This page is designed to offer you information and resources so that you can actively and confidently participate in the climate planning process in your community.
Here are some of the most commonly used terms in conversations about climate change and their definitions. These definitions are based on information provided by leading agencies such as the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration and the Environmental Protection Agency.
Adaptation: In contrast to mitigation, adaptation involves a change of behavior or strategy to minimize risk and make use of opportunities presented by an evolving climate.
Anthropogenic: In relation to climate change, anthropogenic refers to the notion that the changes being observed are the result of human activity.
Cap and Trade: Largely an economic concept, cap and trade refers to a type of market regulation intended to reduce greenhouse gas emissions over time. A cap and trade system involves the establishment of an overall cap on the amount of greenhouse gas emissions permissible in a market, accompanied by the sale of permits to and among businesses allowing them to emit a certain amount of greenhouse gases.
Carbon Capture: Similar to sequestration, carbon capture is a mechanical process by which carbon dioxide gas is trapped at its source and isolated or stored.
Carbon Dioxide: Perhaps the most well-known of the greenhouse gases, carbon dioxide, or CO2 is a molecule comprised of one carbon atom and two oxygen atoms. It is naturally occurring and is also produced as the result of human activities.
Carbon Footprint: This term refers to the amount of carbon dioxide emissions attributable to one person, organization, or region’s activities. It is sometimes generalized to include all greenhouse gas emissions, not just carbon dioxide.
Carbon Neutral: To be carbon neutral, a person or organization needs to remove as much carbon dioxide from the atmosphere as they emit over a specific period of time.
Carbon Sink: Any natural entity that absorbs or retains more carbon than it emits is a carbon sink. The two most prominent examples include plants or trees and the oceans.
Climate: Simply put, climate is the type of weather that is expected in a particular region within a certain period of time. For example, we expect August in northern Virginia to be hot and humid. The weather from day to day in August may be blazing hot, or cool with a breeze, but our general expectations for the weather are defined by our understanding of the climate and trends in prior years.
Ecosystem Services: This term describes the benefits the natural world imparts to humans such as clean air, crop pollination, and waste decomposition. These services are not always fully represented in economic models but they are an important part of any conversation about climate change.
Emissions: A large portion of any conversation about climate change is likely to touch on greenhouse gas emissions. Technically speaking, emissions are gases that enter the air either through a natural or mechanical process.
Fossil Fuels: A fossil fuel is a naturally occurring substance such as oil, coal, or natural gas that formed from the remains of living beings. Fossil fuels are non-renewable, once they are burned or otherwise converted into energy, they are consumed and cannot be regenerated. When fossil fuels are burned or consumed in an internal combustion engine, they emit greenhouse gases that contribute to climate change.
Greenhouse Gas: Every gas with molecules composed of three or more atoms is considered a greenhouse gas. Greenhouse gases come in many shapes and sizes, but they share some common characteristics. Chief among them, the ability to trap heat. These gases allow the sun’s light to pass through but make it harder for the radiant heat from the Earth to escape our atmosphere. For more info, read our Greenhouse Gases Explained article.
Global Warming Potential: There are numerous greenhouse gases in the atmosphere, and some are more potent than others, meaning they cause changes to the climate more readily. The global warming potential of any greenhouse gas is measured by how much heat it traps in the atmosphere over a certain period of time as compared to carbon dioxide.
Mitigation: Generally speaking, mitigation is an effort to slow or stop something from happening. In the context of climate change, mitigation refers to actions intended to reduce greenhouse gas emissions to slow the rate of climate change.
Ozone: Chemically speaking, ozone is O3, or a molecule composed of three atoms of oxygen. In the upper atmosphere, ozone is naturally occurring and is critically important as it helps reduce the amount of ultraviolet radiation that reaches the Earth’s surface. In the lower atmosphere, ozone is a major contributor to smog and is generally the result of human activities. Ozone in the air we breathe can cause respiratory issues for children and adults.
Renewable Energy: The simple definition of renewable energy is energy from a source that is not depleted as it is used. Examples include wind and solar energy.
Resilience: In everyday conversation, resilience describes the ability to adapt to or bounce back from a difficult situation. In climate conversations, it means generally the same thing. Climate resilience refers to our ability to endure and recover from climate impacts like flooding, heat waves, droughts, or the spread of infectious disease.
Scope: In conversations about greenhouse gas emissions it is often useful to discuss sources in terms of proximity to an organization. Scope 1 emissions are the direct result of an organization’s activities or of activities under their control. Scope 2 emissions are the result of the generation of energy that is eventually used by the organization, they are indirect emissions. Scope 3 emissions include all other indirect emissions related to an organization’s operations.
Sea Level Rise: This one is fairly self-explanatory; it refers to the expansion of the oceans and seas as they warm over time. Sea level rise is connected to climate change insofar as the oceans warm in response to temperature increases in the atmosphere and the melting of sea ice. The consequences of sea level rise for coastal communities could be devastating over time.
Sequestration: Carbon sequestration refers to the process of capturing and storing atmospheric carbon dioxide. This process occurs naturally and also through human-driven actions. Carbon can be sequestered biologically in trees, oceans and deep soil. It can also be sequestered using chemical and physical processes such as the conversion of carbon dioxide to solid carbon flakes.
Weather: In contrast to climate, weather is a short-term phenomenon. When we talk about weather, we describe current conditions or expected conditions in the near term. We often include temperature, precipitation, pressure, humidity, wind, and cloud cover when we discuss weather, similar to conversations about climate.
Two degrees. It sounds minimal, no matter the context. But scientists, the media, politicians, and academics all talk about this figure with a sense of anxiety, at least when it comes to climate change. It is entirely reasonable to wonder, what’s the big deal?
Back in 2015, world leaders gathered in Paris for the 23rd Conference of the Parties and hammered out a landmark agreement to collectively keep the global average temperature from rising more than two degrees Celsius above pre-industrial levels. That is to say, above the global average temperature in 1860 or so. This wasn’t the first time two degrees Celsius had been referenced as an acceptable threshold for climate warming. In fact, it was first suggested by an economist from Yale in 1975 as a reasonable approximation of the amount of warming that might naturally take place on Earth over time. In the intervening decades, scientists posited that a one-degree temperature increase globally would be the safest target but that two degrees was a fair upper limit to bear in mind.
In 2018, the Intergovernmental Panel on Climate Change issued a report on the potential impacts of global warming in excess of 1.5 degrees Celsius and compared the magnitude of changes between 1.5 degrees of warming and two degrees of warming. This report illustrated significant differences between the two scenarios. For example, in a world that has warmed by 1.5 degrees Celsius, 14 percent of the global population would experience an extreme heat wave at least once every five years. In a world that has warmed by two degrees, 37 percent of the global population would be subjected to the same scenario – more than twice as many people.
On opposite sides of a very important coin, both water scarcity and sea level rise would be compounded by this incremental change in the global average temperature. With 1.5 degrees of warming, more than 350 million people would be affected by water scarcity. With two degrees, more than 411 million people would experience the consequences of severe drought, that’s a 17 percent increase. With 1.5 degrees of warming, up to 69 million people would be at risk of flooding from sea level rise. With two degrees of warming, that figure increases to as many as 80 million people, that’s nearly a 16 percent increase. These are not small numbers and the costs of this seemingly miniscule difference in global temperature don’t end there. From lower crop yields to serious reductions in plant, animal, and insect species, to the complete extinction of coral reefs, the list goes on and on.
These impacts will never be uniform -- a 1.5 or two degree rise in the global average temperature does not equate to a 1.5 or two degree increase in temperatures here in Fairfax County, necessarily. And people living in landlocked states or countries will not experience the consequences of sea level rise as coastal residents may. The trick is, in order to make a real difference in the upward trend of the global average temperature, everyone needs to play a part.
In late 2019, the UN Environment Programme issued their tenth Emissions Gap Report and said, “By 2030, [global greenhouse gas] emissions would need to be cut 25 percent and 55 percent lower than 2018 to put the world on the least-cost pathway to limiting global warming to below 2° C and 1.5° C respectively.” In other words, the longer we wait to make changes, the more expensive it will become to do so, both financially and in terms of human life and suffering.