25 terms you should know to understand the climate change conversation

Written by:
October 22, 2020
Photomontage // Shutterstock

25 terms you should know to understand the climate change conversation

For the fifth year in a row, global leaders surveyed for the World Economic Forum’s Global Risks Report cited the impact and likelihood of environmental threats—including "extreme weather, climate action failure, and human-led environmental damage"—as the greatest perils facing the globe in the next decade. But one doesn’t have to wait 10 years to see that prediction shake out: Almost daily there’s more news about climate change exacerbating natural disasters like storms, floods, and wildfires, impacting tourism, threatening many species with extinction, or creating cultural shifts like refugee crises because farms become deserts or inhabited islands are abandoned as sea levels rise.

As more of a spotlight is focused on these pressing issues, so, too, appear a myriad of associated buzzwords—from fossil fuels and carbon to biofuels and ozone. And as the climate change conversation becomes increasingly ubiquitous and complicated, it’s helpful to have a grasp on some of its most significant terms—starting with the definition of “climate change” itself.

At its most fundamental, climate change refers to new weather patterns sustained over time (decades to thousands or even millions of years) because of fluctuations in the Earth’s climate system (atmosphere, biosphere, cryosphere, hydrosphere, and lithosphere). The planet has gone through many significant (and natural) climate changes over the past 4.5 billion years, including ice ages and global melts. Then, about 12,000 years ago, the climate reached stable temperatures hospitable to humans. The resulting farming and settling that occurred led to a need for fuel to power newly invented machines; people found it in coal. But as the coal burned, it released the carbon it held. Then came the oil industry in 1859, when Edwin L. Drake drilled the first oil well. All that burning of fossil fuels for industry and transportation—and methane from livestock and the burning of natural gas—has sent much higher levels of emissions into the air than ever before, fueling a period of global warming that is happening faster than at any time in the past 2,000 years. After thousands of years with average temperatures barely fluctuating by more than a degree Celsius, many experts agree the world is likely to experience three degrees of warming by the end of this century. That’s because for the first time, we’re seeing what civilization’s effect on the Earth’s climate system is—and how it affects all of us.

Stacker compiled 25 terms related to climate change, their meanings, and their significance in the context of today’s warming climate. This gallery is not inclusive (thousands of terms relate to the climate change discussion), but is meant as a starting point to better understand what is arguably shaping up to be the most pressing issue of the near—and distant—future.

You may also like: Notable events in the history of Earth Day

1 / 25
Cherries // Shutterstock


Weather is the specific state of the atmosphere at any given time and in any given place over a limited period (minute to minute, day to day, or week to week). Weather can fluctuate wildly over the course of a month or year, and anomalies in weather patterns, such as heat waves or extreme cold, are not evidence for or against global warming or climate change. July 2019 being the hottest month on record represents a weather pattern that could be construed as an anomaly. But when contextualized, scientists have found that the period between 2014 and 2020 contained the warmest seven years on record—a fact that illuminates a larger climate pattern taking shape.

2 / 25
Piyaset // Shutterstock


Climate refers to weather patterns over time based on statistical data. Weather trends are indicative of larger climate patterns when the trends can be charted over at least a 30-year span. The Navy in August 2019 shut down its climate change task force, an initiative established during the Obama presidency to ready naval leadership for changes in the ocean, including sea-level rise and ocean temperature, related to climate change.

3 / 25
Robert Szymanski // Shutterstock

Ice sheet

Ice sheets are continental glaciers exceeding 19,000 square miles. In one 24-hour period in August 2019, Greenland’s ice sheet lost 11 billion tons of ice. While it’s normal for the ice sheet to lose some ice every summer (and regain some in the winter), 2019’s melt season came almost a full month early and was exacerbated by record high temperatures.

4 / 25
FloridaStock // Shutterstock

Global warming

Global warming, an increase in average global temperature over an extended period, is one aspect or symptom of the much larger problem of human-caused climate change. Today’s global warming is attributed to high levels of emissions, including carbon dioxide, methane, and chlorofluorocarbons.

5 / 25
Ugis Riba // Shutterstock

Carbon dioxide

The chemical compound carbon dioxide (one part carbon and two parts oxygen) is a gas produced by respiration and the burning of carbon and other organic compounds. Plants absorb carbon dioxide during photosynthesis, making the gas a fundamental component of all life on earth. Carbon dioxide traps heat radiating off the Earth’s surface in its atmosphere, making the planet habitable for plant and animal life to thrive. Excessive carbon dioxide in the atmosphere creates a “greenhouse effect” attributed to today’s warming climate. By studying air bubbles trapped in ice, NASA scientists have confirmed that today’s carbon dioxide levels exceed CO2 levels of the past 400,000 years.

6 / 25
nEwyyy // Shutterstock


Parts per million, or ppm, is the mass ratio between a pollutant and the air, soil, water, bodily fluid, or other solution. The latest carbon dioxide measurement by NASA in February 2021, for example, showed levels at 416 ppm. For reference, carbon dioxide levels in various ice ages were roughly 200 ppm and 280 ppm during periods of a milder climate. Carbon dioxide levels in 2013 exceeded 400 ppm for the first time ever recorded; left unchecked, that ratio is expected to exceed 1,500 ppm and signal an uncharted climate never before inhabited by human life.

7 / 25
Syda Productions // Shutterstock


Methane is a natural gas comprising one carbon and four hydrogen atoms. It releases less carbon dioxide than other fossil fuels when burned, but is roughly 30 times as strong as CO2 in trapping heat in the atmosphere, making it an even greater climate change threat. The amount of methane being released into the atmosphere has more than doubled in the past 250 years because of forest fires, natural gas fracking, and mass-produced cattle for meat, and accounts for 20% of global warming, according to Yale Environment 360.

8 / 25
Ody_Stocker // Shutterstock


Emissions refer to the expulsion of something (most commonly gases or radiation). When it comes to climate change, emissions might refer to smog over high-density cities like Los Angeles or greenhouse gases released by vehicles. President Joe Biden is seeking to switch American drivers from gas guzzlers to cars that run on electricity, combating climate change through the creation of cheaper electric vehicles, in addition to tax credits and rebates to incentivize the transition.

9 / 25
Lukas Schulze // Getty Images


Conference of the Parties (COP) is the decision-making entity of the United Nations Framework Convention on Climate Change (UNFCCC), an environmental treaty that took effect in May 1992. Annual meetings of the COP (begun in March 1995) negotiate the Kyoto Protocol, review the state of climate change and how countries are dealing with it, and decide to implement aspects of the convention. Today, every country in the world is part of the UNFCCC with the goal of drafting and meeting climate goals. A UNFCCC report in August 2019 outlined how various countries are reacting to its mandates and looked at the status of support for countries in achieving different climate goals, while a 2021 virtual meeting emphasized the need for swift action on the part of the world's governments.

10 / 25
Photoagriculture // Shutterstock


Tillage refers to a variety of methods for preparing to plant crops, whether by turning over soil, raking it, or digging into topsoil. Because tillage disturbs the top layers of soil, tilling large swaths of land can decrease water absorption, subject topsoil to being blown or washed away by wind and rain, and disrupt a soil’s ability to hold nutrients and microbes. Tillage and the use of fertilizers have been blamed for the loss of as much as a third of all arable land in the past 40 years, making past calamities like the Dust Bowl more inevitable in the future.

11 / 25
Jeff Zehnder // Shutterstock

Fossil fuels

Fossil fuels are any natural fuels, such as coal, petroleum, and natural gas, made up of organisms that lived millions of years ago. Humans grew dependent on fossil fuels during the Industrial Revolution; fossil fuels today are found in 96% of everyday items, from plastics to heating fuel. Mining and drilling for fossil fuels—not to mention the act of burning them for fuel—send high levels of carbon dioxide into the atmosphere, exacerbating global warming. Meanwhile, coal-fired power plants are responsible for up to 42% of mercury emissions in the United States and 66% of sulfur dioxide emissions.

12 / 25
Richard Whitcombe // Shutterstock

Ocean acidification

Ocean acidification is the lowering of pH levels in oceans, caused by ocean water absorbing carbon dioxide from the atmosphere. Because seawater exists naturally at a slightly acidic pH level of over 7 (neutral pH is 7), acidification drops water levels to below 7. Changes in pH levels like this can dissolve the shells or skeletons of marine life and make fish less capable of spotting predators. Scientists also believe ocean acidification will negatively affect popular seafood, hurting ecosystems and economies around the world.

13 / 25
thanis // Shutterstock

Particulate matter

Particulate matter (PM-10) includes airborne aerosols that are 10 millimeters or less in diameter such as soot, tiny particles from garbage or fertilizers, or other small pieces of solids that move around in the air causing respiratory irritation. PM-10 causes the biggest risk to humans, as it can be inhaled but can also enter the bloodstream. One August 2019 study by the Multi-City Multi-Country Collaborative Research Network found that these airborne pollutants affect people in more than 650 cities around the world. Many of these pollutants come from sources that exacerbate climate change and, specifically, global warming.

14 / 25
Sean Gallup // Getty Images


Intended nationally determined contributions, or INDCs, are an agreed-to lessening of greenhouse gas emissions under the United Nations Framework Convention on Climate Change (UNFCCC). Countries around the world adopted such agreements at the UNFCCC Conference of the Parties in December 2015 in Paris, specifically looking at actionable climate goals under the Intended Nationally Determined Contributions. These goals dovetail with already-arrived-at goals of the Paris Agreement, including reaching net-zero emissions before 2100 and keeping the global average temperature from rising 2 degrees Celsius.

15 / 25
Katharine Moore // Shutterstock

Antarctic sea ice

Antarctic sea ice fluctuates throughout the year, reaching its greatest depths in September and lowest measurements in February. The start of 2019 represented the lowest levels of sea ice on record for that time of year.

16 / 25
AFP // Getty Images


The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations, dedicated to providing the world with an objective, scientific view of climate change; its natural, political and economic impacts and risks; and possible response options.

17 / 25
Romaset // Shutterstock

Greenhouse gas

Greenhouses gases absorb CO2 and chlorofluorocarbons, and in effect, contribute to the greenhouse effect in the Earth’s lower atmosphere. A greenhouse gas absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

18 / 25
Egor Valeev // Shutterstock

Global average temperature

NASA’s Goddard Institute for Space Studies (GISS) data show that the Earth's global temperature has increased since 1880 by about 2 degrees Fahrenheit, or a little more than 1 degree Celsius. Global average temperatures in 2017 rose 1.62 degrees Fahrenheit (0.9 degrees Celsius) above the 1951 to 1980 mean. The global mean surface air temperature for that period was estimated at 57 F (14 C), according to GISS. That means the planet's average temperature has increased by about 0.8° Celsius (1.4° Fahrenheit) since 1880, according to the surface temperature in 2017 at 58.62 F (14.9 C) and according to GISS’s ongoing temperature analysis.

19 / 25
Chokniti Khongchum // Shutterstock


Biofuel is produced through contemporary processes from biomass, rather than by the slow geological processes involved in the formation of fossil fuels, such as oil. Liquid biofuels can help meet transportation fuel needs. In April 2021 the U.S. Department of Energy announced a $61.4 million initiative for technologies producing low cost and low carbon biofuels, which will help get America to a net-zero emissions economy by 2050.

20 / 25
Hulton Archive // Getty Images

Pre-industrial levels of carbon dioxide

Pre-industrial levels of carbon dioxide refer to the carbon dioxide concentration in the atmosphere before the Industrial Revolution. Scientists estimate these pre-industrial levels were about 280 PPM, well below where we are today. Today, atmospheric carbon dioxide levels are at their highest point in more than 800,000 years.

21 / 25
Jacob_09 // Shutterstock


Ozone in the Earth’s stratosphere keeps living things on the planet safe from radiation that has been associated with health problems like skin cancer. The use of products like aerosols have been shown to deplete this gaseous layer, which inspired the signing of the Montreal Protocol, a global agreement to gradually stop using products that negatively affect the ozone layer.

22 / 25
Matthew J Thomas // Shutterstock

Sea level rise

As the planet warms, glaciers melt and lead to sea-level rise. Global sea levels have risen by about 21 centimeters since the early 1900s. Close to 40% of the U.S. population lives in highly populated coastal areas, putting almost half of Americans and their homes at risk from erosion, flooding, and storms—all exacerbated by global warming. Cities like Miami already are bracing for an anticipated sea-level rise of more than six feet by 2100, which would put the south Florida counties of Monroe, Miami-Dade, and most of Broward underwater.

23 / 25
PJ photography // Shutterstock

Algal bloom

Harmful algal blooms (HABs) are spikes in algae in waterways that can be spotted by their discoloration and prevalence along shorelines. HABs are caused by high levels of nutrients, from sewage to pesticides, that wash off lawns in rainstorms. They are toxic to all animals and suck the oxygen out of the water, causing die-offs of fish and other marine life. In summer 2019, HABs throughout U.S. ponds and lakes caused illness and death in several dogs.

24 / 25
imacoconut // Shutterstock

Renewable energy

Just like it sounds like, renewable energy is energy generated from renewable resources, such as the sun, geothermal heat, rain, tides, or wind. Renewables are the fastest-growing source of energy in the U.S., increasing a full 100% from 2000 to 2018, and accounted for more than 17% of the net U.S. electricity generation in 2018. President Biden's infrastructure plan makes renewables a key component of America's energy economy.

25 / 25
maxbelchenko // Shutterstock


Mitigation is done to reduce the intensity of something; in the case of climate change, this could be anything from planting trees to decrease levels of carbon dioxide in the atmosphere to harnessing renewable energies to decrease humans’ reliance on fossil fuels. In August 2019, the cities of Austin, Texas, and Seattle, Washington, passed ordinances designed to mitigate climate change. Seattle established its own iteration of the Green New Deal and Austin declared a climate change emergency.

Trending Now