Consider the Paris agreement’s preamble, which states that signatories will work to keep the rise in average global temperature “well below” 2 degrees Celsius and even suggests that the increase could be kept to 1.5 degrees. This is empty political rhetoric. Based on current carbon dioxide emissions, achieving the target of 1.5 degrees would require the entire planet to abandon fossil fuels in four years.
But the treaty has deeper problems. The United Nations organization in charge of the accord counted up the national carbon-cut pledges for 2016 to 2030 and estimated that, if every country met them, carbon dioxide emissions would be cut by 56 gigatons. It is widely accepted that restricting temperature rises to 2 degrees Celsius would require a cut of some 6,000 gigatons, that is, about a hundredfold more.
The Paris treaty is not, then, just slightly imperfect. Even in an implausibly optimistic, best-case scenario, the Paris accord leaves the problem virtually unchanged. Those who claim otherwise are forced to look beyond the period covered by the treaty and to hope for a huge effort thereafter.
. . . Acknowledging the Paris treaty’s flaws does not mean endorsing the Trump administration’s apparent intention to ignore climate change. Real progress in reducing carbon emissions and global temperatures will require far-reaching advances in green energy, and that will mean massive investment in research and development—an annual global commitment of some $100 billion, according to analysis by the Copenhagen Consensus. When green energy is economically competitive, the whole world will rush to use it.