When it comes to climate change, deforestation can cause a major effect on it. Trees absorb CO2 and convert it to O2, meaning that CO2 would linger in the atmosphere for much longer than normal, meaning that the earth would heat up much faster than it should.
This means that new trees must be planted, as well as not cut down as much, to reduce the amount of CO2 being emitted into the atmosphere, meaning that climate change would increase drastically. With sea levels rising causing mass flooding, and biodiversity being drastically reduced, this issue is something that needs to be resolved as soon as possible.