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Climate Report Co-Author: 'The Pile Of Evidence Is Now Enormous'

ARI SHAPIRO, HOST:

It's no longer a question. The U.N. says the human impact on the Earth's climate is unequivocal, and things will get far worse unless countries take dramatic action immediately. Professor Kim Cobb is one of the lead authors of the report. She's a climate scientist and director of the Global Change Program at the Georgia Institute of Technology. Welcome.

KIM COBB: Thanks for having me.

SHAPIRO: This report has been described as an alarm, a wake-up call. And so in the last day since it came out, what do you make of the reaction from the international community? Has it been as vigorous as you would have hoped?

COBB: Well, I think it's great to be having these conversations at the pace that we're having them because, frankly, this is long overdue. The pile of evidence is now enormous. Human activities are warming the planet. And this isn't news in 2021, but what is new is that we now have abundant, solid lines of evidence linking this warming to any number of impacts, including weather and climate extremes across land and the ocean.

SHAPIRO: You say it's good that we're having the conversations, but conversations are kind of the equivalent of thoughts and prayers unless they're backed up by actual commitments, right?

COBB: Right. Yes. The report makes it very clear that to keep warming to a minimum this century, which would be another half a degree Celsius on top of the one degrees where we are, we have to enact, collectively, deep and sustained reductions in greenhouse gas emissions to achieve that goal and, of course, limit the impacts mid-century and for the ensuing decades through the end of the century.

SHAPIRO: And meanwhile, China plans to continue increasing its use of coal. Many politicians here in the U.S. seem uninterested in taking dramatic action. So I have to ask, even though this report says the worst-case scenario can be avoided, when you as a scientist look at the evidence, do you think it will be avoided?

COBB: Well, it's not my job to weigh those kinds of odds as a scientist, but it is my job to communicate the core findings of this report so that policymakers who are weighing their actions can do so with the full information in their hands. And most importantly, this information is useful not just to weigh whether we're going to enact the kind of ambitious and sustained reductions that would limit the pace of warming going forward but also policies to protect communities from changes that are already - we're already grappling with today and changes that we know from this report will continue to occur over the next 20 years while we turn this around. That's my note of optimism.

SHAPIRO: You say this report clearly documents the impacts of climate change. And more than that, it documents the connection between human activity and the changing climate, and that is an innovation in the science since the last major U.N. report eight years ago. Can you explain how this works, how scientists can now definitively state that human activity is causing these climate changes in a way that maybe eight years ago scientists were not able to do as definitively?

COBB: Yeah, there are a couple of things to note here. No. 1 is that the records themselves have gotten longer, and it doesn't sound like very much - 10 years more information in the books - but it does make a big difference. The second thing that has improved in this assessment relative to the previous assessments is the improvement in the ability of climate models to capture more and more features of our climate system more accurately.

And the third big innovation - and specific to the identification of human-caused extremes in our climate system - is our ability to use those climate models in kind of a near-real-time digestion, a whodunit to assess critically and quantitatively, what is the role of greenhouse gases in driving that specific extreme and how it played out on our world several days ago - a huge innovation, a huge effort by the scientific community and one that has really advanced this particular area of science.

SHAPIRO: Does your research give you any reason to be optimistic, to be hopeful?

COBB: Yes, certainly. My research has brought me to the front lines of climate change. I've been an eyewitness to a coral bleaching and mortality event in the middle of the Pacific Ocean caused by a marine heat wave. But on the other end of that devastation, we see some of the resilience that nature can bring to even the worst classes of climate extremes that are raining down right now. And so it's important to remember that there is resilience baked into ecosystems. There is resilience baked into human systems. But the further we push this, the less resilient we are. That's one of the take-homes from this report. That's one of the core reasons to try to do all we can to limit warming to the bare minimum by mid-century and then reserve the right to cool for the remainder of this century. That's what we're working towards.

SHAPIRO: Kim Cobb is a climate scientist at the Georgia Institute of Technology and one of the authors of the new U.N. climate report. Thanks a lot.

COBB: Thanks for having me. Transcript provided by NPR, Copyright NPR.