In 1992, more than 150 countries agreed in Rio de Janeiro to stabilize emissions of carbon dioxide and other greenhouse gases at a level that would “prevent dangerous anthropogenic interference with the climate system” — United Nations-speak for global warming.
Many follow-up meetings have been held, long on aspiration but short on action. Emissions have gone up, as have atmospheric temperatures, while the consequences of climate change — droughts, floods, explosive wildfires in both familiar and unexpected places, melting glaciers and ice caps, dying corals, slow but inexorable sea level rise — have become ever more pronounced.
Beginning on Oct. 31, in Glasgow, the now 197 signatories to the Rio treaty will try once again to fashion an international agreement that might actually slow and then reliably (and, it is hoped, quickly) reduce emissions and thus prevent the world from tipping into full-scale catastrophe late in this century. As with other climate meetings — notably those in Kyoto in 1997, Copenhagen in 2009 and Paris in 2015 — Glasgow is being advertised as a watershed event. John Kerry, the former secretary of state who led the American negotiating team in Paris and will lead this one, called Glasgow the world’s “last best chance” to avoid ecological calamity. President Biden said he will “be there with bells on,” and 100 other world leaders are set to attend, including, of course, the host, Prime Minister Boris Johnson, but not, at least so far, President Xi Jinping of China, which is by far the world’s largest emitter of greenhouse gases.
Of all the earlier meetings, Paris was the most successful, in part because negotiators agreed to abandon years of fruitless efforts to achieve legally enforceable targets, instead eliciting modest voluntary pledges, known as nationally determined contributions, from nations large and small to do the best they could as part of a collective effort to keep the average global temperature from rising 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above preindustrial levels — just a few tenths of a degree hotter than the world is today. The 1.5 number was believed then, as it is now, to be a threshold beyond which lie warming’s most serious consequences.