It's basic physics man. This has been understood for over 100 years. Welcome to the 19th century.
As another reply above points out, this is about making predictions about specific behaviors and trends in a super-massively-chaotic system. The number of variables able to substantially change outcomes is staggering in a system as massively-chaotic as the Earth.
When we have the computing power to model and predict the precise orbits of every bit of rock in the asteroid belt bigger than a basketball, you *might* have sufficient computational muscle to be able to create a model accurate enough to make life-and-death decisions for billions of people. Until then all you have is hand-waving, and that's with a 'gimme' assumption that the proper data is able to be acquired to construct such a model and that the algorithms work properly.
Sorry, but humanity does not yet possess sufficient understanding of global climate nor the computing power necessary to create models with sufficiently-small margins of error to justify many of the extreme actions/measures that are being called for by alarmists.