Until the early 20th century, natural factors caused atmospheric carbon dioxide concentrations to vary within a range of about 180 to 300 parts per million by volume (ppmv). Since that time, human activities have increased carbon dioxide emission and have risen the Earth’s CO2 concentration to an unprecedented level.
Greenhouse gases cause climate change by trapping heat and stopping it from escaping into space. They are responsible for warming the world and affecting many other climate changes, including sea level rise and the loss of ice sheets.
Our planet’s climate is regulated by the balance between the amount of incoming energy from the sun, and the amount of outgoing energy as it leaves Earth’s surface. Any factor that alters the balance can cause climate change.
The most important contributors to climate change are emissions from burning fossil fuels, such as coal, oil and gas. The carbon dioxide, methane and nitrous oxide produced by these fuels are greenhouse gases.
Other greenhouse gases, such as chlorofluorocarbons and others, are also produced by human activity in smaller quantities. They affect climate by interacting with infrared radiation, which is what our bodies use to regulate our temperature.
There is a lot of uncertainty about how much warming will occur in the future, because there are many feedback processes that can affect global climate. These include changes in water vapor, ice, clouds and ocean circulation.
It is important to remember that while some benefits of climate change are already occurring, such as longer growing seasons for agriculture and a shorter ice-free season for shipping on the Great Lakes, it is likely that these will be reversed if we do not take action now to reduce the emissions of heat-trapping greenhouse gases.
People, animals, plants, ecosystems and economies are changing as a result of climate change. This is causing major impacts on communities across the United States and around the world.
Some of these impacts have already been seen, and are having a direct impact on our health, economy, and quality of life. For example, higher temperatures and rising levels of carbon dioxide are causing more frequent and intense heat waves. This can make it difficult for people to control their temperature and may increase the risk of heart disease, strokes, skin cancer, kidney and liver diseases.
These impacts will likely continue to grow and become more serious in the coming years, especially as our climate continues to warm and more extreme weather events occur. These effects will disproportionately impact poorer communities, which are often not equipped to adapt.
Our solutions to climate change must include a combination of both short- and long-term strategies. These include adaptation, which helps people prepare for the changes that are already happening, and mitigation, which aims to slow down or stop the rate of emissions.