Green house effect
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in a planet’s atmosphere warm its lower atmosphere and surface. It was proposed by Joseph Fourier in 1824, discovered in 1860 by John Tyndall,was first investigated quantitatively by Svante Arrhenius.
On Earth, naturally occurring amounts of greenhouse gases have a mean warming effect of about 33 °C (59 °F).Without the Earth’s atmosphere, the Earth’s average temperature would be well below the freezing temperature of water.The major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone (O3), which causes 3–7%.]Clouds also affect the radiation balance through cloud forcings similar to greenhouse gases.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750.
Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. The rest of this increase is caused mostly by changes in land-use, particularly deforestation.Estimates of global CO2 emissions in last year from fossil fuel combustion, including cement production and gas flaring, was 34.8 billion tonnes (9.5 ± 0.5 PgC), an increase of 54% above emissions in 1990. Coal burning was responsible for 43% of the total emissions, oil 34%, gas 18%, cement 4.9% and gas flaring 0.7%.
In May 2013, it was reported that readings for CO2 taken at the world’s primary benchmark site in Mauna Loa surpassed 400 ppm, this is likely the first time CO2 levels have been this high for about 4.5 million years.Monthly global CO2 concentrations exceeded 400 ppm in March 2015, probably for the first time in several million years. gross domestic product per capita and population growth were the main drivers of increases in greenhouse gas emissions. CO2 emissions are continuing to rise due to the burning of fossil fuels and land-change.