When the Intergovernmental Panel on Climate Change — the consortium of scientists responsible for summarizing the world's climate knowledge and releasing it in roughly decadal, 3,000-plus-page installments — published its latest report on Monday, the findings were just as grim as usual. The report warned that greenhouse gas emissions are now higher than at any point in human history and continue to grow, despite countries' weak efforts at diplomacy. Every year, nations spew 59 gigatons of greenhouse gases into the atmosphere. For the world to have even a sliver of a chance to meet its goals under the Paris Agreement, the scientists warned, emissions must peak no later than 2025 and then enter a precipitously steep decline.
But hidden on page 25 of the "Summary for Policymakers" was an even grimmer note: That even in the IPCC's most optimistic models, the chances of holding global warming to less than 1.5 degrees Celsius (2.7 degrees Fahrenheit) — compared to the pre-industrial average — is only around 38 percent. In short, even if countries were to defy their history of delay and act heroically quickly to boost clean energy, the odds are that it won't be enough. For all intents and purposes, the 1.5-degree threshold has already passed. We just don't know it yet.
