wylesienie in English:

deforestation cutting down trees in a large area

And to get more land, they need to cut down trees – which is called deforestation. It's deforestation – cutting down forests – that causes greenhouse gases from wood and soil to be released.

There isn’t much fresh air anymore because of deforestation.

The group I was a part of were acting to stop deforestation by trying to educate people about the problem.