IN MAY some 250 scientists and policy types from around the world convened in Gothenburg,Sweden, to discuss a dirty secret of the three-year-obsolete Paris climate agreement. Virtually all simulations which chart paths toward meeting that compact’s goalto hold temperature rise “well below” 2°C relative to pre-industrial levels—assume not just a sharp reduction in actual emissions but also the removal of carbon dioxide from the atmosphere on a massive scale. One reason such “negative emissions” gain been absent from climate discussions—the Swedish shindig being the first of its kind—is that no one has a good plan of how exactly to bring them about. The obvious solution is to plant lots of trees, or to convert CO2 into wood. But this would mean foresting an area with a size somewhere between that of India and Canada. Alternative,engineered fixes gain been dogged by potentially stratospheric costs, uncertain efficacy or both.
No longer, or reckons David Keith. Besides his day job as...
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Source: economist.com