AP Fact Checks DEM's Climate Science

CNN town hall with Democratic presidential candidates Wednesday 9/4/19

ELIZABETH WARREN: “We’ve got, what, 11 years, maybe, to reach a point where we’ve cut our emissions in half. ... We’d better be willing to put the resources into it because the alternative is unthinkable.” .

AP FACTS: These statements are out of step with science. Climate scientists don’t agree on an approximate time frame, let alone an exact number of years, for how much time we have left to stave off the deadliest extremes of climate change.

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PETE BUTTIGIEG : "For me and everybody I know, for the children that we hope to have, for the people who will be alive at the turn of the century, when if we don't change what we're doing, we could lose half the world's oxygen because of what's going on in the oceans. That is unthinkable." 

AP FACTS: This is not sound science.  Climate scientists told The Associated Press that Buttigieg's claim that half of Earth's oxygen is at risk is false. You and your descendants can breathe easy about the planet's oxygen levels. There are other things to worry about from climate change, fossil fuel combustion and Amazon fires."

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BETO O'ROURKE, proposing U.S. leadership on climate change: "Convene those other top wealthy economies to make sure that this is our focus, to save the lungs of the planet that produce 6 percent of the oxygen that we breathe and to ensure that we do not trigger a crisis in the Amazon. Once it is set, we will never be able to roll back. " 

AP FACTS: Lands of the Amazon are not "the lungs of the planet." That's a familiar phrase but not an accurate one. Oxygen production comes primarily from ocean sediments, not forests, which indeed generate oxygen but also consume it.

https://apnews.com/9d6adce79a774aa195e9e33b745d9fa0 
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A report by the U.N. Intergovernmental Panel on Climate Change, drawn from the work of hundreds of scientists, uses 2030 as a prominent benchmark because signatories to the Paris climate change agreement have pledged emission cuts by then. But it’s not a last-chance, hard deadline for action as Warren and other Democratic candidates have cast it.

“The hotter it gets, the worse it gets, but there is no cliff edge,” James Skea, co-chairman of the report, told The Associated Press.

Climate scientists certainly see the necessity for broad and immediate action to address global warming, but they do not agree that 2030 is a point of no return.

Cornell University climate scientist Natalie M. Mahowald told the AP that a 12-year time frame is a “robust number for trying to cut emissions” and to keep the increase in warming under current levels.

But she said sketching out unduly dire consequences is not “helpful to solving the problem.”

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—"That one is indeed a howler," said Michael E. Mann, director of the Earth System Science Center at Pennsylvania State. Global oxygen concentrations "are maintained by long-term geological cycles and nothing here is going to alter that in any significant way."

—"If climate change is left unchecked, the atmosphere could lose about a tenth of one percent of its oxygen content by the end of the century," said Jonathan Overpeck, professor at the University of Michigan's School for Environment and Sustainability. "There is no science behind the idea that we could lose half the world's oxygen. Instead, it's only a tiny amount. ... One thing we don't have to worry about is oxygen levels in the atmosphere."

—While burning fossil fuels does use up oxygen, it's a far smaller amount than Buttigieg suggests, said Texas A&M University climate scientist Andrew Dessler. He calculated the figures and came up with at most a reduction of oxygen of about 2%, adding "this is an absolute upper limit. More reasonable estimates would be much, much smaller, probably less than a few tenths a percent. And this is if we burn everything."

—Atmospheric scientist Scott Denning of Colorado State University has estimated that if oxygen production were to stop now, Earth would have 1 million years of oxygen left.

Such scientists see an urgent need to do more to address the emissions that are warming the climate and bringing profound change to life as billions know it. Depletion of atmospheric oxygen is not one of those changes.

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"Even if all plants in the Amazon stopped doing photosynthesis, we would not notice," Jonathan Foley, executive director of Project Drawdown, a global climate solutions, told the AP. "It would take millions of years for the atmosphere to run out of oxygen."

The Amazon is key in draining heat-trapping carbon dioxide from the atmosphere. Scientists also see grave consequences to nature and communities from fires in the rainforest. But Earth is not losing its lungs.