What Has Worked to Slow Global Warming

by Emil Morhardt

Last week, in anticipation of the United Nations climate conference in New York, The Economist concluded that the single most important action to slow global warming so far has been enactment of the Montreal protocol. Say what? This isn’t on most environmentalists’ radar as an important factor. The Montreal protocol is the 1987 international agreement to save the ozone layer by phasing out Freon and other chlorofluorocarbons used in refrigeration. But these substances are powerful greenhouse gases as well as destroyers of stratospheric ozone, and the protocol caused millions of tonnes of them not to be released into the atmosphere. The article concludes that this avoided release of the greenhouse gas equivalent of 5.6 billion tonnes (bt) of CO2. This is about twice as much avoided CO2 as the next two most effective actions, global use of nuclear power (2.8 bt) and hydroelectricity (2.2 bt), and four times that of the fourth most effective action, China’s one-child policy (1.3 bt). I’m guessing that most of the 300,000 demonstrators in New York last week are not proposing an expansion of these latter three items, but their past effectiveness does make one think. The most effective actions taken specifically to reduce energy usage and CO2 emissions have been worldwide adoption of renewables (0.6 bt), US vehicle emissions standards (0.5 bt), and Brazil forest preservation (0.4 bt). The remaining 11 items on The Economist’s list are small potatoes, totaling less than 1 bt collectively.

Looking ahead, the magazine anticipates that by far the largest future gains will be through a combination of Brazil forest preservation and China enterprise energy efficiency and the further implementation of renewable energy in China, with fairly large returns also possible from additional US vehicle codes, appliance standards, decisions about US refrigerant gases, and UN Clean Development Mechanisms (investments made by developed countries to offset greenhouse gas emissions in developing ones, so the developed countries won’t need to, more-or-less. It also seems likely to me that the effectiveness in producing natural gas from fracking, thus offsetting the need for burning coal (which produces much more CO2 per unit energy got out of it) ought to have a significant effect also, a sentiment apparently shared by Climate Action Tracker, the group on which The Economist relied for its prognostications (“A rapid phase out of coal as an electricity source by 2050 would reduce warming by half a degree, according to the Climate Action Tracker” (http://climateactiontracker.org/) (September 24, 2014)

Now this isn’t a technical paper of the sort we usually review here—indeed the anonymous author(s) referenced no published research other than citing “…figures from governments, the EU and UN agencies” for past results and Climate Action Tracker for looking into the future , but there is an active literature on all of these issues and we’ll be posting about various aspects of it going forward.


Anonymous. 2014. Briefing: Curbing Climate Change—The Deepest Cuts. The Economist, Sept 20th-26th, 2014: 21–23.

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