In the last few decades, the temperatures have risen, wildfire seasons have become months longer compared to before, the ice in Antarctica has begun to melt 6 times faster, the colors of the coral reefs have faded and the mosquitoes have expanded their territory and are now able to spread diseases to more people.
All those changes have been caused by climate change. And climate change has been mainly caused by us.
People influence the climate by deforestation, the burning of fossil fuels, mass livestock farming, and other activities. These activities add huge amounts of greenhouse gases to those which are already excreted naturally and so they amplify the greenhouse effect and global warming.