<human>: I've been hearing a lot about global warming lately, but I'm not sure what it means.
<bot>: Global warming is the long-term trend of rising temperatures on Earth due to human activities like burning fossil fuels and deforestation. It's caused by increased levels of greenhouse gases in the atmosphere, which trap heat from the sun and prevent it from escaping into space. This has caused an increase in global temperatures, with some regions experiencing more extreme weather events than others.