Greenhouse gases in the atmosphere have increased sharply since 1958 and primarily due to Industrial Revolution. Since industrial revolution, human activities have led to an increase contribution of unnatural sources of greenhouse gases into the system, causing the system to become unbalanced.Life on Earth depends on solar energy. Light reaching Earth's atmosphere from the sun passes through the air and clouds to the surface, and on the surface, it is absorbed and then radiated back in the form of infrared heat. Close to 90 percent of this heat is then absorbed by the greenhouse gases and radiated back toward the surface, which is warmed to a life-supporting average 15 degrees Celsius.
Greenhouse gases are naturally occurring gases that pose no danger when they are in balance but when they are in high quantity, the system becomes unbalanced. Most climate scientists agree the main cause of the current global warming is human expansion of the greenhouse effect that results when the atmosphere traps heat radiating from Earth toward space. The Earth maintains a habitable temperature due to the Greenhouse Effect, which allows heat from the sun to penetrate the atmosphere, where it is absorbed by the Earth’s surface or radiated out and reflected back to Earth by greenhouse gases in the atmosphere. Without this, the Earth would be a cold and hostile planet, and would most likely be uninhabitable.Both natural and human factors contribute to global warming, evidence has shown that the warming we are currently witnessing is largely as a result of human activities. Several indications provide evidence that humans are the cause of global warming rather than it being due to natural variability includes: warming oceans, atmosphere boundary shifts and rising surface temperatures. The most important greenhouse gases in the atmosphere are carbon dioxide, methane, nitrous oxide and water vapor. All these gases occur naturally in the atmosphere, emissions from human sources has caused their levels to increase to a point that is no longer sustainable.
Atmospheric carbon dioxide concentrations have risen by more than 40% from 280 parts per million (ppm) in 1958 to over 400ppm today since scientists first started recording these levels. The human source of Carbon dioxide is from burning fossil fuel such as coal to generate electricity, burning oil to power vehicles and aircraft, or burning wood in fires used for cooking or for home heating, cement manufacture etc. These causes the change of state of stored organic carbon from a liquid (i.e., oil) or solid (i.e., coal/wood) into a gas (carbon dioxide) which is released into the atmosphere.These effects have added CO2 to the atmosphere faster than it can be taken up by the land biosphere and the oceans.Deforestation also contributes to carbon dioxide in the atmosphere. Vegetation absorbs CO2 from the atmosphere during the process of photosynthesis, converting this to carbon which is stored in plants (carbon sink). When vegetation is burned, this organic carbon is released into the atmosphere in the form of carbon dioxide, and this way it becomes a carbon source rather than a carbon sink.
Although methane has a shorter lifespan, it is not as abundant in the atmosphere as carbon dioxide, in terms of it effect as a greenhouse gas, it is much more strong. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide. Methane is produced when organic matter breaks down and also it can be produced when ruminants digest their food. Human contribution of methane in the atmosphere by decomposition of organic matter in landfills, animal waste, sewerage, agriculture (i.e., rice cultivation) and dams. In the decomposition process, bacteria produce methane which slowly escapes to the surface and therefore released into the atmosphere. Methane also escape during oil and gas extraction operations and then released to the atmosphere.
Nitrous Oxide is a powerful greenhouse gas produced by soil cultivation practices, mainly the use of commercial and organic fertilizers, fossil fuel combustion, biomass burning and nitric acid production. Atmospheric nitrous oxide levels have risen by roughly 18% since the Industrial Revolution, and this rapid increase occurred towards the end of the 1900’s.
Water vapor is the most abundant greenhouse gas; it is important because it acts as a feedback to the climate.Water is essential for life, and as it is constantly cycling from one state to another. However, water vapor not only acts as a greenhouse gas, it also increases as the atmosphere gets warmer and provides climate feedbacks. Humans do not play a direct role in producing water vapor, but human emissions promote atmospheric warming, which in then promote evaporation that results in more water vapor released in the atmosphere.
These are synthetic compounds entirely of industrial origin used in a number of applications such as aerosols, foaming agents, refrigerants. They are long lasting greenhouse gases that destroys the ozone layer.
To understand how humans cause global warming as we have seen, it is important that we are aware of the link between our daily activities and the greenhouse effect. Once we understand this, it is easy to see that you have the power to help stop global warming from getting worse. The effects of global warming have the potential to be devastating to humanity and to the whole planet, which is why you must act now. For example, you can reduce your impact on the climate by greening your transport, eating vegetarian or vegan.