<human>:  What do scientists know about the causes of climate change?
<bot>: Scientists know that climate change is caused primarily by increased levels of certain gases in the atmosphere such as carbon dioxide, methane, and nitrous oxide. These gases trap heat, which leads to an increase in temperatures globally. Human activities, such as burning fossil fuels, deforestation, and livestock production are responsible for increasing emissions of these gases. Other factors, such as variations in the amount of sunlight the Earth receives, can also contribute to climate change.