Understanding Greenhouse Gas Emissions and Climate Change: Key Indicators and Impacts
Greenhouse gases from human activities are the primary driver of observed climate change since the mid-20th century. These gases, such as carbon dioxide, methane, nitrous oxide, and fluorinated gases, are released into the atmosphere through various human activities like burning fossil fuels, agriculture, and industrial processes. As these gases accumulate in the atmosphere, they trap heat and lead to global warming, causing significant changes in the climate.
In the United States, greenhouse gas emissions have decreased by 2.3 percent from 1990 to 2021, with carbon dioxide being the main contributor to these emissions. Transportation and electricity generation are the largest sources of greenhouse gas emissions in the US. Globally, net emissions of greenhouse gases have increased by 43 percent from 1990 to 2015, with carbon dioxide accounting for three-fourths of total emissions.
The concentrations of greenhouse gases in the atmosphere have been steadily increasing since the industrial era, with carbon dioxide levels reaching unprecedented levels compared to the past 800,000 years. This increase in greenhouse gases leads to a positive climate forcing effect, causing the Earth’s energy balance to change and resulting in warming over time.
Major greenhouse gases associated with human activities have different characteristics, including their sources, average lifetimes in the atmosphere, and global warming potentials. Carbon dioxide, methane, nitrous oxide, and fluorinated gases all contribute to the greenhouse effect, with varying levels of impact based on their properties.
To track greenhouse gas emissions in the US, the Environmental Protection Agency (EPA) has two key programs: the Inventory of U.S. Greenhouse Gas Emissions and Sinks and the Greenhouse Gas Reporting Program. These programs provide data on emissions from various sources and industries, helping policymakers and the public understand the sources of greenhouse gas emissions and make informed decisions.
Overall, the increase in greenhouse gas emissions from human activities has significant implications for the climate, leading to changes that affect people, society, and the environment. It is crucial to continue monitoring and reducing greenhouse gas emissions to mitigate the impacts of climate change and protect the planet for future generations.