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Public Radio's Environmental News Magazine (follow us on Google News)

Extreme Weather Events and Climate Science

Air Date: Week of

Years of insufficient rainfall across the Horn of Africa have caused the worst drought in 40 years. In the picture above two boys walk to their settlements in Hadhwe sub-district, which has been particularly hard hit by the drought. (Photo: Mulugeta Ayene, Flickr, CC BY-NC-ND 2.0)

Scientists have understood for decades how global warming would increase moisture in the atmosphere promoting climate disruption and extremes such as the floods, wildfires, and record-breaking heat waves that 2022 has brought to many regions. But there may be more impacts to come as climate models haven’t captured all the complex interactions of a warming world. Michael Mann, Professor of Atmospheric Science at the University of Pennsylvania, joins Host Steve Curwood to discuss.


CURWOOD: From PRX and the Jennifer and Ted Stanley Studios at the University of Massachusetts Boston, this is Living on Earth. I’m Steve Curwood.

Extreme weather, it seems, is now almost the norm, despite the horrendous toll it’s taking on humans and countless other species. Science started warning us decades ago that global warming would increase atmospheric moisture and lead to climate disruption, and now we are living with the predictions of those climate models. For some insights into extreme weather and what the models did and did not predict we turn now to Michael Mann, a professor of Atmospheric Science at the University of Pennsylvania, and he joins us now from Philadelphia. Welcome back to Living on Earth Michael!

MANN: Thanks, Steve, always great to be with you.

CURWOOD: So, in these last few weeks, we've seen just crazy intense weather, a third of Pakistan flooded now, after they had record heat earlier this summer, cities all over the United States and places from Death Valley to St. Louis, to Dallas and most recently, we're looking at the problem in Jackson, Mississippi, where flooding has taken out the water system. What’s going on? What's happening in terms of climate disruption?

MANN: Yeah, well, you know, it's not rocket science, you warm up the planet, as we're doing with carbon pollution, you're going to get more of these extreme heat waves, more frequent heat waves, so that's a no brainer. You also warm up the atmosphere, so it holds more moisture. So when it does rain, you get more rainfall, you get more precipitation, you get more of those flooding events. And the the heat dries out the soils in the summer so you get worst drought, more widespread drought. You combine the heat and the drought, you get the sorts of catastrophic wildfires that we're seeing out in the western US that we're seeing in Europe that we've seen down in Australia. So that part is all pretty straightforward, it's all basic physics. But there's something else on top of that, which is a little more subtle, and which isn't all that well captured in the climate models. It's the way that the pattern of warming is changing the behavior of the Jet stream, its causing it to get stuck in more of a wiggly pattern, where you get those big high and low pressure systems associated alternatively with extreme heat, drought and wildfire or extreme flooding, and they remain sort of locked in place. So you get those extreme heat conditions day after day in the same location or rainfall day after day in the same location. That's when you see the most profound extreme weather impacts when you get these very persistent extreme weather events. And climate change appears to be leading to an increase in those persistent weather extremes in a way that isn't well captured by the climate models. If anything, we've under predicted that the impact of climate change on these extreme weather events that we're seeing. And what's happened is those events have now, the signal has now risen above the noise. We're noticing the impacts were feeling the consequences. Because the signal the impact of climate change on the frequency and intensity of these events, has now risen above the noise of natural variability. It's plain to see. And we can see it now playing out in real time.

CURWOOD: So this is not a fair question but what else do you think that climate modeling has not captured all that well, that could be in our in our future? In an uncomfortable way?

MANN: Yeah. So these extreme weather events are one example of where the physics is pretty subtle. The physics behind the Jet stream behavior that I was talking about is subtle enough that it's not well captured in the climate models. So it comes down to some of the physics that isn't really represented well enough in the models. That there's other physics that isn't, or at least traditionally hasn't been well represented related, for example, to ice physics and the behavior of ice sheets. And one of the other things that we've seen is that the ice sheets are losing ice faster, earlier than we expected earlier than the models predicted. And we can see why there are processes that we're seeing play out, again, in nature, that haven't been well represented in the models, for example, the cracks that formed the fissures that form in the ice sheets that allow the melting surface water to penetrate to the bottom of the ice sheet and lubricate the base, which allows it to slide out to the ocean more quickly. Or the destabilization of ice shelves, like we see off the West and Antarctic coast. These ice shelves help prop up the inland ice. Now when the ice shelf collapses or melts, it doesn't contribute to sea level rise, because it's already floating on the water. It's like an ice cube in a glass of water. But when those ice shelves do collapse, that removes the buttressing effect that holds back the inland ice and that inland ice can start to surge up to sea. And so we're seeing these processes lead to earlier loss of ice from the Greenland and West Antarctic ice sheet and that means the sea level rise from ice melt is happening earlier than we expected. So it's another example of how uncertainty isn't our friend. Look, the climate models have been really good about predicting the overall warming of the planet. More than a half century ago, the predictions that were made of how much warming we would see if we continue to burn fossil fuels at historic rates have come to pass. The predicted warming is what we've actually seen. What's been under predicted are some of the consequences of that warming.

CURWOOD: Among the sort of unusual weather things this year has been the lateness of the hurricane season. What if anything, do you think might be going on there? Is it just a random thing, because you know, occasionally these things happen or might we be looking at perhaps some sort of a trend change here?

Pakistan experienced the worst floods in a century affecting more than 33 million people and causing more than 1,343 deaths. (Photo: Ali Hyder Junejo, Flickr, CC BY 2.0)

MANN: Yeah, no, I would say stay tuned. I think we would be wrong to dismiss this season at this point. We haven't reached the peak of the season, we’re close to it. But we haven't reached the seasonal peak. And one thing we know about La Niña years, this is a La Niña year. The tropical Pacific is cooler than usual, that affects weather patterns around the world. And it actually often leads to more active hurricane seasons in the Atlantic, but late in the season. When it kicks in is the fall. So stay tuned. I think when all is said and done, we will look back at this season as having been an average season, not a record inactive season, but a relatively at least by historical standards, an average season. And here's the thing, we've gotten used to this sort of increase, which is connected to climate change in hurricane behavior in the Atlantic, that what in the end, I think will simply be an average season historically feels like an incredibly inactive season. So stay tuned, you know, I think we're going to see a ramp up in activity in the weeks ahead.

CURWOOD: So recently, we saw the inflation Reduction Act get passed with on the order of 370 billion, maybe as much as 400 billion dollars to be devoted to dealing with climate, both in terms of reducing emissions and also adapting to the trouble that climate disruption is giving us. I wonder to what extent do you think that finally happened, because we've seen such horrible events over the last few years? I mean, the wildfires are like routine news now in the western part of the United States, amazing flooding. This summer's heat waves are really extra intense in the northern hemisphere but we've been in this situation for a while. To what extent do you think that as a society as a population, we've passed a tipping point on climate?

MANN: Yeah, you know, I think that obviously, the Biden administration was supportive of climate action contrasting with the previous administration, with the Trump administration, and was, you know, using the bully pulpit really to encourage and to push Congress into passing climate legislation. But it came down in the end to whether one or two Democrats would be willing to support some sort of climate legislation, and Joe Manchin, a coal state Democrat who had in general had opposed any aggressive climate action has been friendly to the fossil fuel industry, was sort of the gatekeeper in what legislation could pass this 50-50 Senate. And I actually do think that the fact that his own people back in West Virginia are feeling the extreme consequences, the flooding events that they've seen in that state devastating floods, in recent years. I think he was feeling the pressure of all of this climate disruption that was playing out in real time as this bill was being discussed and considered. And I think in the end, it did play a role. And that's really critical, because now Joe Biden can go to COP 27, the next international climate conference and say- look, the United States is meeting or at least coming really close, we need to do more and we need to arguably elect an even larger majority in Congress to pass more aggressive climate legislation. But the inflation Reduction Act comes really close about 40% reductions in carbon emissions by 2030, what we really need is 50%. But it puts us in the ballgame. And Joe Biden can say- look, we're now acting, we're making meaningful progress here in the United States, I think that will lead other countries like China and India, to make more aggressive commitments to ratchet up their own commitments as well. And so the most important impact of the inflation Reduction Act might be its impact on international climate policy and the stature that it now gives Joe Biden were the US the world's largest historical polluter, we now can say the rest of the world we're trying to do our part, please do your part as well.

CURWOOD: We have to take on the responsibility for their loss and damage it sounds like.

MANN: Absolutely, you know, some of this should be thought of as reparations. We reaped the economic you know, rewards of two centuries of dirty energy burning of fossil fuel energy, we grew our economy, but at the expense of the quality of life for the rest of the world. So there is an obligation on our part to help those who have suffered some of the worst consequences and yet played the least, you know, the least role in creating the problem in the first place.

CURWOOD: So, Michael, you study this of course so much of your career. It seems that when we look at these extreme weather events and the impact of climate disruption, that if one is poor or brown, or in the Global South, that it's it's much worse. And yet, of course, the less affluent part of the world did not create these emissions as you point out. To what extent is there still a gap in US policy to helping the rest of the world deal with the ravages of climate? I mean, look, a third of Pakistan is underwater, it's a pretty poor place.

MANN: Yeah, you know, it is really ultimately, it's an issue of ethics, right? We often frame climate change as a problem of science or policy or politics but it's a problem of ethics. Intergenerational ethics, the notion that we could leave behind a degraded planet for our children and grandchildren, but also the ethics of inequality, inequity, wealth disparity, the fact that the Global South, that low income communities, frontline communities are feeling some of the worst consequences of climate change, and yet have the least resources to deal with those consequences. And that, you know, catastrophic flooding in Jackson, Mississippi really captures that quandary, I think, quite profoundly. It's a travesty that hundreds of thousands of people are either without drinking water or drinking polluted water because of neglect. You know, because frankly, the Republican politicians in that state really have provided no commitment, no infrastructure to help the people there deal with these sorts of natural disasters. And this isn't a natural disaster anymore, it's an unnatural disaster. It's been made worse by human caused warming. So, you know, what it really shows us is that we need to provide resources to those frontline communities to low income communities to help them deal with the the impacts that can't be avoided. We've got to prevent whatever warming we can and that requires more aggressive climate policy that requires people voting in these midterm elections coming out to vote for climate, you know, champions and voting out those who have acted as apologists for the fossil fuel industry. So we can get even more aggressive climate action and meet that 50% target that we really need to meet. That's important but at the same time, we've got to provide resources to people to cope with those impacts that are now unavoidable, that are now baked in. And in particular, that applies to those frontline communities, those low income communities. And it's not just the United States, we need to make sure that the US and the you know, industrial world provides support in the form of loans and outright grants of money to developing countries to help them cope with the devastating consequences they're already feeling. And to help them leapfrog past the fossil fuel stage. Make sure that they don't make the same mistake that we made.

CURWOOD: Michael Mann is a senior scientist, senior atmospheric scientist at the University of Pennsylvania. Thanks so much for taking the time with us today.

MANN: Thanks, Steve. Always great to be with you.



Michael Mann at the University of Pennsylvania

The Third Pole | “Floods After Drought Devastate Sindh’s Agriculture”

The Conversation | “America’s Summer of Floods: What Cities Can Learn from Today’s Climate Crises to Prepare for Tomorrow’s”

The Washington Post | “Living in A City with No Water: ‘This Is Unbearable’”


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