The Atlantic reports: The world’s highest-ranking diplomats are meeting in Paris this week to complete the final version of a new UN agreement on climate change.

They are working on a 48-page draft resolution, prepared during the first week of the talks by lower-ranking climate ministers. One of the questions they’ll take up during the week to come: Should the world’s nations attempt to limit climatic warming to 1.5 degrees Celsius, instead of the previously agreed-upon 2 degrees?

1.5 degrees has become one of the most surprising stories of Paris. Many observers expected the international community to drop the two-degree target at the Paris talks due to its scientific impracticability. Instead, thanks to climate activists and sustained diplomacy from the countries most vulnerable to sea-level rise, it might settle on an even more ambitious target. The United States and China have both signaled tentative support for 1.5, despite Saudi Arabian and Indian opposition.

Yet actually achieving 1.5 degrees will be extraordinarily difficult. Speaking to The Atlantic Monday morning from Paris, President Obama’s top science advisor said that it will be an near impossible target to meet. [Continue reading…]