Even ardent supporters acknowledge that the Paris treaty by itself will do little to rein in global warming. The United Nations estimates that if every country were to make every single promised carbon cut between 2016 and 2030 to the fullest extent and there was no cheating, carbon dioxide emissions would still only be cut by one-hundredth of what is needed to keep temperature rises below 3.6 degrees Fahrenheit (2 degrees Celsius). The Paris treaty’s 2016-2030 pledges would reduce temperature rises around 0.09 degrees Fahrenheit by the end of the century. If maintained throughout the rest of the century, temperature rises would be cut by 0.31 degrees Fahrenheit.
Lomborg calculations using the best peer-reviewed economic models show the cost of the Paris promises – through slower gross domestic product growth from higher energy costs — would reach $1 trillion to $2 trillion every year from 2030. U.S. vows alone — to cut greenhouse-gas emissions 26 percent to 28 percent below 2005 levels by 2025 — would reduce GDP by more than $150 billion annually.
So Lomborg's thinks Trump’s promise to dump Paris will matter very little to temperature rises, and it will stop the pursuit of an expensive dead end.
Keohane of the Environmental Defense Fund has a critique of Lomborg in Forbes
1. The effectiveness of U.S. climate policies.
Keohane argues that the US Clean Power Plant legislation that puts the first-ever limits on climate pollution from electric power plants. Impacting overall temperature which will take more than one country and many years. The government’s analysis of the Clean Power Plan finds that benefits (largely from reduced climate pollution, but also from cleaner air) will outweigh costs by $25 to $45 billion dollars by 2030.
2. The duration of the Paris Agreement.
Lomborg mischaracterizes the Paris Agreement as lasting only through 2030 in order to ignore policies after that year. While the specific pledges countries made in advance of Paris run through 2030, the Agreement itself was purposely written to be open-ended and long-lasting. Indeed, one of the most important parts of the agreement is the “ratchet provision” requiring countries to submit new targets every five years and to increase ambition in each submission.
Nextbigfuture translates as yes if all current Paris promises are kept it will have the minimal impact that Lomborg calculates but Koehane wants to put weight on future promises that are yet to be made.
3. The lasting effect of policies.
Keohane expects the Paris promises to be kept after the agreement.
4. China’s peaking commitment.
Lomborg simply ignores China’s Paris commitment to peak its carbon dioxide emissions by 2030. Instead, he assumes that China’s emissions rise rapidly through the end of the century.
Keohane says Lomborg mischaracterizes the results of an MIT analysis that he claims agrees with his own. But he overlooks an important difference: In estimating the impact of the Paris pledges, the MIT study separates out the effect of the Paris commitments from previous pledges made in 2009 and 2010. Lomborg effectively lumps them all together, by comparing the Paris outcomes to a no-policy scenario. Moreover, the MIT study (unlike Lomborg) is careful to take China’s peaking commitment into account.
Nextbigfuture notes that China has promised to peak its carbon dioxide emissions before. Those promises were outside of a climate agreement. Keohane thinks the promises matter more when made in the non-binding Paris agreement.
5. Are the costs worth the benefits?
Keohane does not want to count the costs after 2030 when the Paris agreement ends. He wants to talk about new promises afterwards and the potential benefits of racheted promises but he does not want to discuss ramping costs.
Lomborg’s claim that the Paris Agreement will cost $100 trillion is a case study in obfuscation and error. He takes a figure for the cost in 2030 that he evidently came up with himself (with zero transparency), applies it to every year of the policy (despite the fact that costs are generally lower in the early years of a policy), extends it to the end of the century (despite only considering policies through 2030), and ignores standard accounting practices (e.g., discounting). Lomborg does not provide details on his methodology, but it is likely that he overstates the cost: his estimate of the costs of meeting the U.S. target, for example, are twenty to thirty times higher than the estimated cost of meeting the Clean Power Plan.
For the sake of analysis, however, suppose we assume the validity of Lomborg’s own annual cost estimate in 2030. Taking into account his 2030 time horizon, and discounting back to the present, a better estimate of the present value of the mitigation cost would be $5 trillion — one-twentieth of Lomborg’s $100 trillion figure.
Nextbigfuture believes there are lower cost and more effective actions that can be taken on climate
There are about 1.3 billion cars on the roads and 70 million new cars and trucks being made. Older cars, motorcycles, small engine devices like lawnmowers are the most polluting. Note older cars would still be around but the 10 most polluting would have accelerated retirement. Other older cars would be given cheap retrofits like the $60 gas filters.
Have a policy of addressing particulates. Having GPF filters and other modifications retrofitted to the existing fleet of cars on the street.
Replace the coal burner at coal plants with cleaner technology. For the next 10-20 years natural gas or better a higher temperature nuclear reactors.
The turbine and grid connections remain. Just replace the coal burner or thermal source. Concentrated solar could be used to help reduce the amount of fuel that is burned.
Factory Mass produce nuclear reactors.
Uprate existing nuclear reactors with new metallic nuclear fuel with more surface area.
Increase battery and solar power by over 100 times.
Use more ride sharing and robotic cars