Greenhouses Gases in Earth’s Atmosphere
The following gases in the Earth’s atmosphere are
known as the greenhouse gases (water vapor, carbon dioxide, methane, nitrous
oxide, chlorofluorocarbons or CFCs and ozone). These gases are naturally
present in the Earth’s atmosphere. Human activities, such as the burning of
fossil fuels (coal, oil and gas) to generate energy have contributed to the
rise in the atmospheric CO2 in the last 200 years.
Carbon Dioxide in the Earth’s Atmosphere
The sources of the atmospheric CO2 include volcanic
eruptions, combustion and decay of organic matter (dead plants and animals),
cellular respiration, burning of fossil fuels, deforestation, and production of
cement by humans.
What
causes Climate Change?
The Greenhouse Effect is known by scientists to be
causing global warming leading to climate change. The greenhouse effect is a
process that occurs when greenhouse gases (water vapor, carbon dioxide,
methane, nitrous oxide, CFCs) in Earth's atmosphere trap the Sun's heat from
escaping into the space. This process makes Earth much warmer than it would be
without an atmosphere.
Scientific
Evidence of Climate Change
Increase in the atmospheric CO2 leads to global
warming of the Earth and causes climate change. The following are the
scientific evidence of climate change: Global Temperature Rise, Warming Oceans,
Shrinking Ice Sheets, Glacial Retreat, Decreased Snow Cover, Sea Level Rise,
Declining Arctic Sea Ice, Extreme Events, and Ocean Acidification.
Global
Temperature Rise
The planet's average surface temperature has risen
about 1.62 degrees Fahrenheit (0.9 degrees Celsius) since the late 19th
century, a change driven largely by increased carbon dioxide and other
human-made emissions into the atmosphere.
Warming
Oceans
The oceans have absorbed much of this increased
heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of
more than 0.4 degrees Fahrenheit since 1969.
Shrinking
Ice Sheets
The Greenland and Antarctic ice sheets have
decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment
show Greenland lost an average of 286 billion tons of ice per year between 1993
and 2016, while Antarctica lost about 127 billion tons of ice per year during
the same time period. The rate of Antarctica ice mass loss has tripled in the
last decade.
Glacial
Retreat
Glaciers are retreating almost everywhere around the
world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa.
Decreased
Snow Cover
Satellite observations reveal that the amount of
spring snow cover in the Northern Hemisphere has decreased over the past five
decades and that the snow is melting earlier.
Sea
Level Rise
Global sea level rose about 8 inches in the last
century. The rate in the last two decades, however, is nearly double that of
the last century and is accelerating slightly every year.
Declining
Arctic Sea Ice
Both the extent and thickness of Arctic sea ice has
declined rapidly over the last several decades.
Extreme
Events
The number of record high temperature events in the
United States has been increasing, while the number of record low temperature
events has been decreasing, since 1950. The U.S. has also witnessed increasing
numbers of intense rainfall events, leading to flooding.
Ocean
Acidification
Since the beginning
of the Industrial Revolution, the acidity of surface ocean waters has increased
by about 30 percent. This increase is the result of humans emitting more carbon
dioxide into the atmosphere and hence more being absorbed into the oceans to
form carbonic acid. The amount of carbon dioxide absorbed by the upper layer of
the oceans is increasing by about 2 billion tons per year. Author:Dr. Sunday Iwalaiye, CPhys, CSciTeach, with contribution from NASA.
