They include communal waste sinks like rivers, lakes and oceans, and the global atmosphere. In all of these areas it looks likely that things will get quite a lot worse before they get better. These kinds of resources and sinks are not under the direct control of people affected by shortage or damage. People wishing to change the way a common resource or sink is used or managed have to pass through the legal or political system. They must organise, take out lawsuits against polluters, pressurise legislators and so on.
Political responses are typically slow.
Usually the majority of voters have to be convinced of the need for action before politicians will risk taking action. Even then powerful and rich vested interests will lobby hard for the status quo, and will often succeed in frustrating changes that are desired by a global majority. America's coal, oil, and car lobbies have stood in the way of any significant US commitment to reduce carbon dioxide output, and the US is the world's largest emitter of carbon dioxide. Usually there has to be very widespread and very visible environmental damage before action is taken. The thinning of the ozone layer fitted that category well and the response was swift.