THE'greenhouse effect It is a process that occurs when gases in the Earth's atmosphere trap heat from the sun, making the Earth much hotter than it would be without an atmosphere.
The greenhouse effect is one of the elements that make the Earth a comfortable place to live.
How does the greenhouse effect work?
As the name suggests, the greenhouse effect works… like a greenhouse! A greenhouse is a building with glass walls and a roof.
Greenhouses are used to grow plants, such as tomatoes and tropical flowers.
A greenhouse stays warm inside, even during the winter. During the day, sunlight enters the greenhouse and warms the plants and the air inside. At night, it gets colder outside, but the greenhouse stays quite warm inside. This is because the glass walls of the greenhouse trap the heat from the sun.
The greenhouse effect works much the same way on Earth: gases in the atmosphere, such as carbon dioxide, trap heat in a similar way to the glass roof of a greenhouse.
These heat-trapping gases are called greenhouse gases.
During the day, the sun shines through the atmosphere and the Earth's surface heats up in the sunlight.
At night, the Earth's surface cools, releasing heat into the air, but some of the heat is trapped by greenhouse gases in the atmosphere.
This is what keeps our Earth warm and cozy at an average of 14°C.
What impact do humans have on the greenhouse effect?
Human activities are altering the Earth's natural greenhouse effect.
Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere.
NASA observed a increase in the amount of carbon dioxide and other greenhouse gases in our atmosphere.4
Too much of these greenhouse gases can cause the Earth's atmosphere to trap more and more heat, causing the Earth to warm.
Which gases cause the greenhouse effect?
The contribution a greenhouse gas makes to the greenhouse effect depends on how much heat it absorbs, how much it reradiates, and how much of it is in the atmosphere.
In descending order, the gases that contribute most to the Earth's greenhouse effect are:
- water vapor (H2O)
- carbon dioxide (CO2)
- nitrous oxide (N2O)
- methane (CH4)
- ozone (O3)
In terms of the amount of heat these gases can absorb and re-radiate (known as their global warming potential or GWP), CH4 is 23 times more effective and N2O is 296 times more effective than CO2. However, there is much more CO2 in the Earth's atmosphere than CH4 or N2O.
Not all of the greenhouse gases we emit into the atmosphere stay there indefinitely.
For example, the amount of CO2 in the atmosphere and the amount of dissolved CO2 in the surface waters of the oceans remain in equilibrium, because air and water mix well at the sea surface.
When we add more CO2 to the atmosphere, some of it dissolves into the oceans.
Anthropogenic Greenhouse Gases
Since the beginning of the Industrial Revolution in the mid-18th century, human activities have significantly increased greenhouse gas concentrations in the atmosphere.
As a result, measured atmospheric CO2 concentrations are many times higher than pre-industrial levels.
Major sources of man-made greenhouse gases
Burning fossil fuels
THE carbon dioxide levels are substantially higher now than at any time in the last 750,000 years.
Burning fossil fuels has raised CO2 levels from an atmospheric concentration of about 280 parts per million (ppm) in pre-industrial times to over 400 ppm in 2018. This is an increase of 40% since the start of the industrial revolution.
The CO2 concentrations are increasing at a rate of about 2-3 ppm/year and are projected to exceed 900 ppm by the end of the 21st century.
If this continues, combined with rising emissions of CH4 and other greenhouse gases, by 2100 the global average surface temperature could rise by up to 4.8°C above pre-industrial levels.
Consequently, some scientists suggest limiting concentrations to keep the temperature change below +2°C.
This would include substantial cuts in anthropogenic greenhouse gas emissions by the mid-21st century through large-scale changes in energy systems and in land use.
Agriculture, forestry and other land uses
Agriculture, deforestation and other land-use changes account for a quarter of net anthropogenic greenhouse gas emissions.
According to a United Nations report, livestock are responsible for approximately 14.5%.
The main sources of emissions are:
- Feed production and processing (45%)
- Greenhouse gas emissions during cow digestion (39%)
- manure decomposition (10%)
- the remainder is attributable to the processing and transportation of animal products.
Higher concentrations of atmospheric CH4 are also caused by changes in land use and wetlands, pipeline leaks, and landfill emissions. Fertilizer use can also lead to higher concentrations of N2O.
Cement production
Cement production releases CO2 into the atmosphere when calcium carbonate is heated, producing lime and CO2.
Estimates vary, but it is widely accepted that the cement industry produces between 5 and 8% of global anthropogenic CO2 emissions, of which 50% is produced by the chemical process itself and 40% by burning the fuel to power that process. The amount of CO2 emitted by the cement industry is more than 900 kg of CO2 for every 1000 kg of cement produced.
Aerosol
Aerosols are small particles suspended in the atmosphere that can be produced when we burn fossil fuels. Other anthropogenic sources of aerosols include pollution from cars and factories, chlorofluorocarbons (CFCs) used in refrigeration systems, and CFCs and halons used in fire-fighting systems and manufacturing processes. Aerosols can also be produced naturally by a range of natural processes, e.g. forest fires, volcanic eruptions and isoprene emitted by plants.
We know that greenhouse gases provide a warming effect on the Earth's surface, but the'aerosol pollution in the atmosphere can counteract this warming effect. For example, sulfate aerosols from fossil fuel combustion exert a cooling influence by reducing the amount of sunlight reaching the Earth.
Aerosols also have a detrimental impact on human health and influence other aspects of the climate system, such as precipitation.
What reduces the greenhouse effect on Earth?
- Just like a glass greenhouse, Earth's greenhouse is also filled with plants.
The plants can help balance the greenhouse effect on Earth. All plants, from giant trees to tiny phytoplankton in the ocean, absorb carbon dioxide and give off oxygen.
- The ocean It also absorbs a lot of excess carbon dioxide from the air. Unfortunately, the increase in carbon dioxide in the ocean changes the water, making it more acidic (ocean acidification).
More acidic water can be harmful to many ocean creatures, such as some mollusks and corals. Warming oceans, due to too many greenhouse gases in the atmosphere, can also be harmful to these organisms: warmer waters are a major cause of coral bleaching.
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