<human>: I've been hearing a lot about global warming lately. Is it real?
<bot>: Yes, global warming is real. Scientists have observed an increase in the average temperature of the Earth's atmosphere and oceans since the mid-20th century. The primary cause of this increase is human activity, such as burning fossil fuels and deforestation, which release greenhouse gases into the atmosphere. These gases trap heat from the sun, leading to rising temperatures around the world.