plastic bags washed up on the beaches, as seen on TV, were from the Asian countries North of us,
Altrav,
Yes, I have observed that first hand in 'The Last Great Wildermess of Cape York'.
Another sobering experience was to travel over the trawling grounds after trawlers worked it all night. Some crews did not really appear to be too concerned what went over the side. Some recreational fishers too leave more than they take.
Another rather un-pretty sight from the helicopter was a famous replica sailing ship emptying its holding tank.
Human activity leaves its mark but to a basic, normal extent it's impact is absorbed by the environment. Where the environment is losing that ability is mass air travel, abuse of electricity, abuse of petroleum-based fuel, abuse of literally everyting humans are involved in. All that though is not the cause of any GW but it surely doesn't reduce it either. It also provides a great, apparent justifiable wasting of billions of Dollars going to people guessing about it all.