“What can we do to stop global warming?”
I’ll rephrase it a little if you don’t mind, “What can we do to stop anthropogenic climate change?”
We have to reduce our emissions (via the burning of fossil fuels, forest destruction etc..) of greenhouse gases by at least 50%. Currently natural sinks appear to take approximately 50% of our annual emissions out of the atmosphere. As such, as long as we emit more than what can be dealt with by natural sinks, then the percentage of GHG’s will continue to increase in the atmosphere. Think of it as a bathtub with a drain hole that can expel a volume of water about half of that which is coming out of the tap.
As such, dropping our collective annual emissions by 20% will slow the rate of increase of atmospheric ghg (or water in the bathtub), but it will not stop climate change. The other thing to remember is that even if we stopped emitting today, there is a large amount of climate inertia, in other words, temperature in the pipeline. This has been estimated to be about 0.6 C of warming last time I checked.
And…there are natural carbon sinks which have potential tipping points and feedbacks. The more we increase global temperatures, the higher the probability that such feedbacks kick in, which are likely to escalate warming further.
So to stop anthropogenic climate change requires global action (hence the push for global climate treaties), and the need for public understanding of the scientific evidence for climate change with associated pressure on governments – to press for rapid reductions in GHG emissions.
Then comes the waiting game to see exactly where global climate stabilize before coming back to the general state of affairs modern civilization evolved with.
Two points: 1) The numbers for natural forcings (ie. solar output, volcanic eruptions, axial tilt, ENSOs) simply can’t account for recent warming, whereas GHGs do.
2) Several aspects including cooling in the stratosphere, increasing nighttime temperatures relative to daytime temperatures, the increase in downward longwave infrared radiation and a decrease in upward longwave infrared radiation with the spectral signatures of ghgs; are all direct supportive evidence for the dominate contribution anthropogenic ghgs are making to recent climate change.