Using fossil fuels removes carbon from the earth, and burning them releases CO2 into the atmosphere. When there is more CO2 in the atmosphere, it warms it up by trapping heat. Because people are releasing more CO2 into the atmosphere, this helps to explain why global temperatures are rising. However, this isn't the only reason behind the increasing temperatures; another cause is the albedo effect.
Fossil fuel emissions that contain carbon dioxide absorb solar radiation when clouds are present in the atmosphere and reflect it back to space when they are not. This means that if fossil fuel emissions increase, then less radiation reaches the surface of the planet to cause global warming. The amount of radiation that does reach the surface depends on the amount of cloud cover over the planet. If there is more aerosol pollution in the atmosphere, then there will be more reflection from those clouds and less radiation will get through to warm the planet further.
The main reason why the climate is changing is because of humans. During the last century, we have released more carbon dioxide into the atmosphere than all previous centuries combined. This has had a large impact on the environment because it has warmed up the planet. Changes to the environment due to human activity are called "anthropogenic factors". These include increased CO2 levels, ocean acidification, land use change, and global warming itself.
During the Industrial Revolution, individuals began to engage in a variety of activities that required the usage of fossil fuels. The amount of CO2 in the atmosphere has increased since the beginning of the Industrial Revolution, so it isn't just a recent phenomenon. Before the use of fossil fuels, less than 0.5% of the world's population lived in cities, now nearly half do. Most of the increase in city-dwellers comes after the revolution, when energy consumption increases due to advances in technology.
Fossil fuels include oil, natural gas, and coal. Oil and natural gas are used in cars, trucks, airplanes, and as fuel for home heating and electricity production. Coal is used to generate electricity online and for heating homes.
People have been using fossil fuels since the 1800s, but only recently have they become widespread. Before this time, people used firewood, animal fat, or renewable resources like bamboo or hydroelectric power. Renewable energy sources are considered clean energy because they don't emit any greenhouse gases or other pollutants during creation or use. The main advantage of fossil fuels is their wide availability and low cost. You can drive almost anywhere in the world and use oil instead of gasoline, which makes these fuels convenient for travelers.
The use of fossil fuels has an impact on the concentration of CO2 in the atmosphere. Both water vapor and CO2 are responsible for global warming, and when CO2 levels rise in the atmosphere, the seas warm, causing an increase in water vapor to follow. This positive-feedback mechanism is called the greenhouse effect.
Carbon dioxide emissions come from many sources other than fossil fuel combustion, such as landfills, trees, and agriculture. However, carbon dioxide emissions from human activities number in the tens of billions of tons per year, which accounts for about 85% of the total gas. The main source of carbon dioxide emissions is the burning of fossil fuels (oil and natural gas), followed by deforestation and soil degradation processes. Animal farming and products from their waste disposal also contribute to climate change, mainly through the emission of methane.
Airplanes too can be a source of CO2 emissions. The aviation industry has become a major emitter of this gas because most planes emit large amounts of CO2 while flying between cities. Passengers on long flights may be able to reduce their environmental impact by choosing direct flights or by switching off appliances such as computers, phones, and TVs. Traveling by train is more environmentally friendly than driving your car, but trains also produce CO2.
The fundamental driver of global warming is the accumulation of carbon dioxide in the atmosphere caused by the combustion of fossil fuels. The global biosphere has been assisting in offsetting some of the extra carbon dioxide that humans have been emitting into the atmosphere. But if this process is to continue, it will need to be done faster than it is currently.
The main way that the biosphere removes carbon dioxide from the atmosphere is through plants. They use the gas for photosynthesis, which creates new biomass that can then be consumed by bacteria or decomposed by fungi or animals. This process is known as "biomass production". Biomass production is one reason why there is less concern about how increasing CO2 will affect climate at the Earth's surface. It means that the planet will be able to absorb more of this gas from the atmosphere and there won't be as much danger of overheating.
But the biosphere also removes carbon dioxide from the atmosphere through physical processes such as erosion and decomposition. As well as removing carbon dioxide from the atmosphere, biomass production also produces oxygen. So even though the biosphere is capable of removing significant amounts of carbon dioxide from the atmosphere, it can't do so forever. Once all the available biomass has been consumed, any further removal would lead to increased levels of atmospheric CO2.
Increased levels of atmospheric gases trap solar heat, resulting in global warming and climate change. The average temperature of the Earth has risen during the previous 150 years. Greenhouse gases trap heat from the sun, warming the atmosphere. They may also reflect some of the sun's energy back to space, cooling the planet.
Greenhouse gases can come from natural sources such as volcanoes and ocean waters, but they also result from human activities such as burning fossil fuels and raising livestock. The main gas responsible for heating up the planet today is carbon dioxide, or CO2. Other gases include methane, nitrous oxide and ozone-depleting substances.
The first scientific study that showed a clear connection between increased carbon dioxide concentrations and global warming was published in 1975 by scientists working for the United States government. Since then, more than 100 other studies have been published by researchers around the world. All confirm that there is a link between rising carbon dioxide levels and increasing temperatures. Some have even estimated how much future warming might be expected if the amount of carbon dioxide in the atmosphere doubles or quadruples due to human activity.
In conclusion, an increase in atmospheric greenhouse gases results in greater absorption of sunlight across the board. This leads to higher average temperatures everywhere you look. We will see what impact this has on our oceans and forests in another lesson though!