If even one of these assumptions is invalid, the requirement for emission reduction policy disappears. Let's look at them again in a little more detail. The first assumption concerns the scientific theory. Within limits I believe this to be well founded, despite the criticisms of sceptics who say it overestimates, and of alarmists who say it underestimates consequential climate change. Assertions that climate models indicate increasing extreme weather are not at all well based.
Scientific uncertainties are still too great for any prediction of such trends to have validity.
A critical analysis of the background evidence from the 1995 scientific update from the Intergovernmental Panel on Climate Change gives no sound grounds to differ from this opinion. As to the second assumption, there is little evidence to support the notion of net deleterious climate change despite recent Cassandra-like trepidation in the Australian Medical Association and exaggerations from Greenpeace. The answer is complicated. In my opinion, it is due partly to the use and abuse of science to foment fear by those seeking to support ideological positions, and partly to the negative and fearful perspective that seems to characterise some environmental prejudices. A gloomy view is enhanced by a tendency among those studying the impact of change to focus on potential damage to systems based on the present climatic state.