John Kerry kisses his two-year-old granddaughter after signing the Paris AgreementMike Segar / Reuters

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This morning, I traveled to the United Nations Headquarters in New York, where representatives from about 170 nations are signing the Paris Agreement. Just now, U.S. Secretary of State John Kerry added his signature with his two-year-old granddaughter on his knee.

What is there to say about such an event? First, there’s the prognostication—the savvy political hazarding of what comes next. One-hundred-sixty nations will be enough to grant the agreement legitimacy; next, 55 nations representing 55 percent of global emissions have to ratify it through national processes. The United States and China, who collectively represent 38 percent, will be able to do so by executive decree.

In other words, it is looking likelier and likelier that the Paris Agreement could activate by the end of 2016. As the French minister of environment and energy said Monday night at the UN, the agreement might be “signed and ratified by the time anybody is elected” president.

But in the longer term, the Paris Agreement will dictate a new global calendar—of new stocktakings and emissions-reduction  goals. From a diplomatic perspective, 2015-2016 will be the year zero for the climate, the place where the world’s plan for dealing with it changed. If we’re lucky, the five-month gap between when the treaty was completed and when everyone signed it will confuse undergraduates for decades to come; if we’re enormously lucky, the scene today will be replayed in every climate-change documentary montage made in the late 2090s.

Lucky because now we have a calendar, and even rudimentary plans for reducing warming, but they are filled with gaps and grossly inadequate. “Outside experts say the countries’ bare-bones plans are still far from enough to keep global warming to tolerable levels” is how The New York Times puts it. The Paris Agreement even assumes that atmospheric carbon-scrubbing technology will become viable in the next several decades.

But other than trees, carbon scrubbers don’t exist yet. We’re still waiting for the miracle to happen.

The atmosphere is filling with greenhouse gases.

For the week beginning April 10, 2016, the Mauna Loa Observatory measured atmosphere carbon dioxide levels of 408.69 parts per million. This week last year, it measured 404.10 ppm. The second week of April in 2006, levels stood at 384.93 ppm.

Renewable energy costs are falling quickly, as oil remains historically cheap.

Despite unsuccessful talks at Doha, oil prices continue to hover at $40.

Inside Climate News was a 2016 Pulitzer finalist for its work in revealing that Exxon knew about the dangerous potential for climate change as early as the 1960s.

I’ll revisit more trends next week.

This week in the Earth system

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