Global warming is caused by increased levels of carbon dioxide and other greenhouse gases in the atmosphere from human activities like burning fossil fuels and deforestation. This traps heat and causes the planet to warm. Effects of global warming include climate change, rising sea levels, changes to water availability, and increased health risks from the spread of diseases. Scientists agree that human activities are the dominant cause of global warming since the mid-20th century based on extensive peer-reviewed research. Ways to prevent further global warming include reducing greenhouse gas emissions through policies, more sustainable energy sources, and changes to transportation and land use.