A change in GDP should change the cost of recycling and pollution costs for example.
This is true, but it should also depend on a lot of other factors as well. If GDP growth is driven by actual growth in output, then what you’ve pointed out is correct. On the other hand, if GDP growth is driven by rising prices/inflation (overheating) and not actual productive growth, then there would be no rise in pollution or the amount of goods to be recycled. There may even be a decrease, as everything would become more expensive.
I’m sure that it could be made conditional.
I expect it to fall when the GDP falls, or maybe fall depending on the values, that’s why I tried to put more neutral sounding language in.