It uses the most robust method, of analysing the Earth’s heat budget over the past hundred years or so, to estimate a “transient climate response” — the amount of warming that, with rising emissions, the world is likely to experience by the time carbon dioxide levels have doubled since pre-industrial times.
The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too. That is to say, up until my teenage children reach retirement age, they will have experienced further warming at about the same rate as I have experienced since I was at school.
At this rate, it will be the last decades of this century before global warming does net harm.
Bottom line from Ridley: “There is little doubt that the damage being done by climate-change policies currently exceeds the damage being done by climate change, and will for several decades yet. Hunger, rainforest destruction, excess cold-weather deaths and reduced economic growth are all exacerbated by the rush to biomass and wind.”
None of this means do nothing. Certainly more energy science research, possibly to enable natural gas to be a bridge fuel to solar. And back in 2011, several AEI scholars illustrated one way a carbon tax might work to deregulate US energy:
Subsidies for ethanol and other alternative fuels would be abolished (basic research on renewable energy would be funded on the same stringent terms as other basic research). As discussed above, business and household energy tax credits would be abolished. Regulations designed to lower greenhouse gas emissions would be repealed. Instead, a tax on greenhouse gas emissions (“carbon tax”) would be imposed.