This is ‘Not Doomed Yet,’ The Atlantic’s weekly newsletter about global warming. It lives here in the science section; you can also get it in your inbox:

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Surely the biggest climate news this week: For the second year in a row, global GDP grew in 2015 while global carbon emissions stayed flat. This terminates a link that had persisted for 200 years, and it suggests that mitigating climate change won't be disastrous for the global economy. Since the Industrial Revolution, fossil fuels—coal for warmth and power; petroleum for asphalt and transport—have driven and even indicated economic growth. Given this history, and given the grave consequences of carbon emissions, it seems no exaggeration to call this the most important political-economy news this millennium. CO₂ emissions aren’t just another economic indicator.

Additionally, 21 countries have grown their economies while shrinking their carbon emissions since 2000, according to new research from the World Resources Institute. They are all developed, post-industrial economies in Europe or the Americas (except for Uzbekistan, where emissions have fallen only 2 percent). The United States is the largest country to have decoupled: Since 2010, its carbon emissions have fallen 6 percent.

But have American emissions actually fallen? In a lengthy feature at The Nation this month, the climate journalist and activist Bill McKibben argues that greenhouse-gas emissions (not just carbon emissions) have possibly increased during the Obama administration, thanks to lost methane from fracking operations. He cites a new a paper (readable in full online) that shows satellite-observed methane releases from the United States have spiked 30 percent since 2002. McKibben’s dire reading of this study tells him that America hasn’t actually decoupled at all; it’s just shifted from emitting carbon to leaking methane. But a more moderate expert whom he consults says the worst-case reading of the study is that “as much as three-fifths of the greenhouse-gas reductions that the United States has claimed” are non-existent, especially in the short term.

Bottom line: There’s evidence that carbon emissions can be reduced without disastrous economic consequences, but without a concerted policy shift to renewable energy, the change won’t even come close to what’s needed.

Finally, this week, in her traditional slot in this newsletter: It’s Elizabeth Kolbert! This week she visits scientists trying to re-engineer two creatures to withstand the climate’s ravages : a chestnut tree resistant to plague, and a coral hardy to bleaching. (Especially relevant given this year’s mass bleaching event.)

Kolbert thinks through how to deploy such projects, implying that assisted evolution’s obstacles are less GMO alarmism than common sense; but this story really belongs in this newsletter because her two main characters tell her, variously:

• “I’m a realist. I cannot continue to hope that our planet is not going to change radically. It already is changed.”

• “Really, what I am is a futurist. [...] Our project is acknowledging that a future is coming where nature is no longer fully natural.”

The Macro-Trends

The atmosphere is filling with greenhouse gases. For the week beginning on April 3, 2016, the Mauna Loa Observatory measured 406.57 carbon-dioxide molecules per million in the atmosphere (ppm).

Last year at this time, the Observatory observed 402.93 ppm in the air. Ten years ago, it measured 384.62 ppm.

These are the most recent final reports on atmospheric carbon, but preliminary reports continue to the present. They indicate that atmospheric CO2 spiked this weekend. On Sunday, April 10, 2016, the Mauna Loa Observatory measured 409.29 ppm of carbon in the air, far and away the highest measurement ever taken at the observatory. Typically, atmospheric carbon will not peak for about another three weeks.

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

1,500 coal plants are currently planned or under construction worldwide. Brad Plumer of Vox writes that stopping the plants—which will happen, in part, by making renewable energy ever cheaper—will be the great environmental story of the next 15 years: “If even one-third of these plants get built and operate for their full lifetime, we’ll likely bust through the 2 degrees Celsius global warming threshold.”

California is beginning to connect its renewable-heavy electrical grid to grids nearby. Dave Roberts examines the local political problems that will arise.

A barrel of oil closed above $40 on Monday evening, one of the few times it has done so this year. But the price of oil won’t significantly shift until April 17, when major oil-producing states meet in Doha to discuss further limits on drilling.

The Obama administration is trying to implement its first major greenhouse-gas-limiting regulations.

Little news on this front this week, other than various regional utility execs in red states admitting that “carbon reduction plans” would come regardless of the Clean Power Plan’s fate. With most amicus briefs filed, there’s unlikely to be much more news here before June 2, when oral arguments in the case will be heard.

However: In Oregon, a magistrate judge has ruled that 21 children have standing to sue the federal government for inaction on climate change under the Fifth Amendment. Magistrate Judge Thomas Coffin ruled on the legal grounds alone that plaintiffs had credibly asserted “a novel theory [that falls] somewhere between” a civil rights/Fifth Amendment action and a Clean Air Act suit. The case now moves to the district court.

China is planning a cap-and-trade program to limit carbon emissions.

Edward Wong looks into whether China’s carbon emissions have actually peaked, as one recent study claimed. Wong is the reporter I most trust on this question.

After Paris

It’s been 16 weeks since the Paris Agreement was reached. Representatives from China, the United States, and other countries will sign it on Friday, April 22, in New York.

The Washington Post, with high confidence and pointed quotes from former Obama administration officials, knowingly speculates that the White House is rushing to activate the treaty before the next administration enters office, effectively locking them into it. The White House can do that because the Paris Agreement takes effect one month after 55 nations, responsible for 55 percent of global emissions, ratify the treaty—and once the U.S. and China sign on, that will be 38 percent of global emissions right there. Once Paris takes effect, the United States could not lawfully withdraw from participation (though it could very easily fail to comply) before 2019 or 2020.

In the next few years, World Bank will spend more than a quarter of its investments on climate-change adaption and mitigation projects.

This week in the Earth system

All the creatures we’re familiar with—the animals, plants, and fungi—are crowded on one thin branch. The rest are largely filled with bacteria. […] And around half of these bacterial branches belong to a supergroup, which was discovered very recently and still lacks a formal name. Informally, it’s known as the Candidate Phyla Radiation. Within its lineages, evolution has gone to town, producing countless species that we’re almost completely ignorant about. With a single exception, they’ve never been isolated or grown in a lab. In fact, this supergroup and “other lineages that lack isolated representatives clearly comprise the majority of life’s current diversity,” wrote Hug and Banfield.

  • I did not know that the current tree of life—featuring eukaryotes, archaea, and bacteria dated only from the 1970s; I also did not know that Darwin (in typically evocative prose) was the first to propose that evolution resembled “a branching tree.”

  • It’s not for another six months, but this drone footage of an Alaskan salmon run is really beautiful.