The greenhouse effect happens when certain gases, which are known as greenhouse gases, accumulate in Earth’s atmosphere. Greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), and fluorinated gases.

 

Greenhouse gases allow the sun’s light to shine onto Earth’s surface, and then the gases, such as ozone, trap the heat that reflects back from the surface inside Earth’s atmosphere. The gases act like the glass walls of a greenhouse—thus the name, greenhouse gas.

 

According to scientists, the average temperature of Earth would drop from 14˚C (57˚F) to as low as –18˚C (–0.4˚F), without the greenhouse effect.

 

Some greenhouse gases come from natural sources, for example, evaporation adds water vapor to the atmosphere. Animals and plants release carbon dioxide when they respire, or breathe. Methane is released naturally from decomposition. There is evidence that suggests methane is released in low-oxygen environments, such as swamps or landfills. Volcanoes—both on land and under the ocean—release greenhouse gases, so periods of high volcanic activity tend to be warmer.

 

Since the Industrial Revolution of the late 1700s and early 1800s, people have been releasing larger quantities of greenhouse gases into the atmosphere. That amount has skyrocketed in the past century. Greenhouse gas emissions increased 70 percent between 1970 and 2004. Emissions of CO2, rose by about 80 percent during that time.

 

The amount of CO2 in the atmosphere far exceeds the naturally occurring range seen during the last 650,000 years.

 

Most of the CO2 that people put into the atmosphere comes from burning fossil fuels. Cars, trucks, trains, and planes all burn fossil fuels. Many electric power plants do as well. Another way humans release CO2 into the atmosphere is by cutting down forests, because trees contain large amounts of carbon.


People add methane to the atmosphere through livestock farming, landfills, and fossil fuel production such as coal mining and natural gas processing. Nitrous oxide comes from agriculture and fossil fuel burning. Fluorinated gases include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). They are produced during the manufacturing of refrigeration and cooling products and through aerosols.


All of these human activities add greenhouse gases to the atmosphere. As the level of these gases rises, so does the temperature of Earth. The rise in Earth’s average temperature contributed to by human activity is known as global warming.


The Greenhouse Effect and Climate Change

Even slight increases in average global temperatures can have huge effects.

 

Perhaps the biggest, most obvious effect is that glaciers and ice caps melt faster than usual. The meltwater drains into the oceans, causing sea levels to rise.

 

Glaciers and ice caps cover about 10 percent of the world’s landmasses. They hold between 70 and 75 percent of the world’s freshwater. If all of this ice melted, sea levels would rise by about 70 meters (230 feet).

 

The Intergovernmental Panel on Climate Change states that the global sea level rose about 1.8 millimeters (0.07 inches) per year from 1961 to 1993, and about 3.1 millimeters (0.12 inches) per year since 1993.

 

Rising sea levels cause flooding in coastal cities, which could displace millions of people in low-lying areas such as Bangladesh, the U.S. state of Florida, and the Netherlands.

 

Millions more people in countries like Bolivia, Peru, and India depend on glacial meltwater for drinking, irrigation, and hydroelectric power. Rapid loss of these glaciers would devastate those countries.

 

Greenhouse gas emissions affect more than just temperature. Another effect involves changes in precipitation, such as rain and snow.

 

Over the course of the 20th century, precipitation increased in eastern parts of North and South America, northern Europe, and northern and central Asia. However, it has decreased in parts of Africa, the Mediterranean, and southern Asia.

 

As climates change, so do the habitats for living things. Animals that are adapted to a certain climate may become threatened. Many human societies depend on predictable rain patterns in order to grow specific crops for food, clothing, and trade. If the climate of an area changes, the people who live there may no longer be able to grow the crops they depend on for survival. Some scientists also worry that tropical diseases will expand their ranges into what are now more temperate regions if the temperatures of those areas increase.

 

Most climate scientists agree that we must reduce the amount of greenhouse gases released into the atmosphere. Ways to do this, include:

  • driving less, using public transportation, carpooling, walking, or riding a bike.
  • flying less—airplanes produce huge amounts of greenhouse gas emissions.
  • reducing, reusing, and recycling.
  • planting a tree—trees absorb carbon dioxide, keeping it out of the atmosphere.
  • using less electricity.
  • eating less meat—cows are one of the biggest methane producers.
  • supporting alternative energy sources that don’t burn fossil fuels.

 

The Greenhouse Effect and our Planet
The greenhouse effect is a vital natural phenomenon, intensified by human activity.

Manmade Gas

Chlorofluorocarbons (CFCs) are the only greenhouse gases not created by nature. They are created through refrigeration and aerosol cans.

CFCs, used mostly as refrigerants, are chemicals that were developed in the late 19th century and came into wide use in the mid-20th century.

Other greenhouse gases, such as carbon dioxide, are emitted by human activity, at an unnatural and unsustainable level, but the molecules do occur naturally in the Earth's atmosphere.

aerosol can
Noun

container of liquid material under high pressure. When released through a small opening, the liquid becomes a spray or foam.

Noun

the art and science of cultivating land for growing crops (farming) or raising livestock (ranching).

Noun

layers of gases surrounding a planet or other celestial body.

carbon
Noun

chemical element with the symbol C, which forms the basis of all known life.

carbon dioxide
Noun

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

chlorofluorocarbon (CFC)
Noun

chemical compound mostly used in refrigerants and flame-retardants. Some CFCs have destructive effects on the ozone layer.

climate
Noun

all weather conditions for a given location over a period of time.

Noun

dark, solid fossil fuel mined from the earth.

Noun

edge of land along the sea or other large body of water.

Noun

agricultural produce.

electricity
Noun

set of physical phenomena associated with the presence and flow of electric charge.

environment
Noun

conditions that surround and influence an organism or community.

Noun

process by which liquid water becomes water vapor.

Noun

overflow of a body of water onto land.

fluorinate
Verb

to add or combine with the element fluorine (F).

forest
Noun

ecosystem filled with trees and underbrush.

fossil fuel
Noun

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

freshwater
Noun

water that is not salty.

gas
Noun

state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.

Noun

mass of ice that moves slowly over land.

Noun

increase in the average temperature of the Earth's air and oceans.

greenhouse
Noun

building, often made of glass or other clear material, used to help plants grow.

Noun

phenomenon where gases allow sunlight to enter Earth's atmosphere but make it difficult for heat to escape.

greenhouse gas
Noun

gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

hydrochlorofluorocarbon
Noun

greenhouse gas often used as an industrial cooling material.

hydroelectric power
Noun

usable energy generated by moving water converted to electricity.

hydrofluorocarbon
Noun

greenhouse gas often used as an industrial cooling material.

Noun

area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.

Industrial Revolution
Noun

change in economic and social activities, beginning in the 18th century, brought by the replacement of hand tools with machinery and mass production.

Noun

watering land, usually for agriculture, by artificial means.

landfill
Noun

site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.

livestock
noun, plural noun

animals raised for sale and profit.

meltwater
Noun

freshwater that comes from melting snow or ice.

methane
Noun

chemical compound that is the basic ingredient of natural gas.

microbial
Adjective

having to do with very small organisms.

Noun

process of extracting ore from the Earth.

molecule
Noun

smallest physical unit of a substance, consisting of two or more atoms linked together.

Noun

type of fossil fuel made up mostly of the gas methane.

nitrous oxide
Noun

greenhouse gas used in medicine and the manufacture of rockets. Also known as laughing gas or happy gas.

Noun

large body of salt water that covers most of the Earth.

ozone
Noun

form of oxygen that absorbs ultraviolet radiation.

power plant
Noun

industrial facility for the generation of electric energy.

Noun

all forms in which water falls to Earth from the atmosphere.

public transportation
Noun

methods of movement that are available to all community members for a fee, and which follow a fixed route and schedule: buses, subways, trains and ferries.

Noun

liquid precipitation.

recycle
Verb

to clean or process in order to make suitable for reuse.

reflect
Verb

to rebound or return light from a surface.

refrigerant
Noun

substance used to keep materials cool.

respiration
Noun

breathing.

Noun

base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

snow
Noun

precipitation made of ice crystals.

Noun

land permanently saturated with water and sometimes covered with it.

temperate
Adjective

moderate.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

tropical
Adjective

existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

vapor
Noun

visible liquid suspended in the air, such as fog.

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.