The issue is we should do more research but we should also act based on what is already known. My main research has been in biomedical areas such as cancer. When I started the five year survival for childhood ALL was about 40% now it is better than 80%.  We still do not know everything but a lot of people are alive because we acted before we know everything.
We know enough about many environmental problems to act to prevent rapid deterioration before we reach a point where we cannot effectively act. If you believe we should let everyone die because we do not completely understand cancer then I suppose you would believe that we should not act on our environmental knowledge.  I suspect there are many who question the ethics of such a position.