How climate change has powered the heat wave blanketing much of the U.S.

[0:00] A massive heat dome has been spreading across much of the United States with temperatures [0:04] reaching historic highs. But it's not an isolated spike. In recent weeks, [0:09] the country has grappled with a series of extreme weather events. [0:13] Allie Rogin has more for our periodic series, Tipping Point. [0:18] John, this heat is not just notable for nearly unprecedented early spring temperatures, [0:22] but also for the amount of ground it's covering. Temperatures have been 20 to 40 degrees above [0:27] normal in the Great Plains, and it's been moving east. Some cities are already seeing [0:32] record-breaking streaks, and the heat is expected to last into early April. That's because a high [0:38] pressure system is acting like a lid, trapping hot air underneath and allowing temperatures to [0:43] rise day by day. The Southwest registered triple digits, with temperatures reaching 101 degrees [0:50] in New Mexico. Kansas also set a March record with 102 degrees twice in four days. For more [0:57] on what we can expect, [0:57] in the coming days, I'm joined by Bernadette Woods-Placky, Chief Meteorologist at Climate [1:02] Central. Bernadette, thank you so much for being here. How unusual is it for us to see this type [1:08] of heat in March? And has this ever happened before? This is wildly unusual. And no, it has [1:16] not happened to this level before. I do think people are used to seeing temperatures spike [1:21] 100 degrees in Phoenix and Las Vegas, but that's usually May, June, July. It's not in March. [1:29] And how far has this heat spread in the country so far, and what can we expect in the coming days? [1:35] Sure. So there's a lot of ways to put together these numbers. And any way you look at them, [1:41] they are breaking records like we've never seen before. One is we broke an all-time [1:46] temperature record for March for the country. We also have had multiple states break their [1:53] all-time March temperature record. We've seen hundreds of records a day happen, [2:00] over this past week. And when you break down the balance of record highs to record lows, [2:06] we took it back all the way to the beginning of the year, because remember, there were some [2:10] cold stretches. But since the beginning of the year, 85 percent of our records have been warm [2:16] or hot records, and only 15 percent have been cold records. So there's a lot of coverage in [2:22] that early-season cold. It's nothing compared to what we're experiencing right now. [2:26] So you mentioned we're seeing record heat, record cold. But why is it that we are seeing [2:31] more record hot weather than cold? [2:33] Well, that's because of climate change. Now, one is the weather pattern. It's extraordinary for this [2:38] time of year. It looks more like a weather pattern we'd see in July. But that weather pattern alone, [2:44] combined with the additional fossil fuel pollution we put into our atmosphere, is why we're breaking [2:50] records to this level. One way you can look at that is, we understand the greenhouse effect. [2:55] This is science that goes back to the 1800s that really isn't challenged. And we can measure those [3:01] in the atmosphere. And we know we're putting more of those into our atmosphere from the burning of [3:06] fossil fuels like oil, coal and gas. So when you thicken that blanket around our atmosphere, [3:12] it traps more heat. The most obvious and direct way that we experience that extra warming on our [3:19] planet is through extra hot days. And now we have been experiencing these heat domes for the last [3:25] 10 years they've been on the rise. What makes them different, though, from just other types of [3:30] early spring warm weather? Well, we've had heat domes before. We've had them this time of year [3:36] before. But what happens underneath those, when you add those extra greenhouse gases in the [3:42] atmosphere, it allows our temperatures to go to levels we've never experienced. So that's the big [3:47] difference right now, is that every time we're using the word unprecedented or record, and it [3:53] feels like it's getting a little old to some people, but it's happening that frequently right [3:57] now that we are pushing record highs to this level. [4:01] This hot weather. [4:01] Is also having implications for things like snowpack and water resources out west. How is [4:07] this going to affect communities, not just in the present, but in the months to come? [4:13] This is a really important part of this conversation because the west as a whole [4:17] has been really low on its amount of snow this year. And you've got to remember that's water. [4:22] That's water for the warmer months. That's how we water our plants and our crops. [4:27] That's also our water resources. So on April 1st, this is a really big day out west where [4:32] we take these measurements across many different areas in the mountains and get an assessment of [4:38] where that snowpack is for the year as we head into these warmer months. We are so low. We're [4:43] record lows. And it really varies from state to state. But it's not only that it's record low, [4:48] this March heat has forced melting earlier than usual. So we're not going to have that water [4:53] in the same ways at the times that we need it. And then that really ups our risk for wildfire. [4:58] The weather just seems to get worse and worse every year, but it's not, [5:02] just extreme heat. It's also things like flooding in Hawaii, rare snow in Alabama, [5:09] shifting temperatures in the northeast. What else can we expect in terms of extreme weather [5:14] for the rest of this year? Well, it's interesting to look at this as a full pattern. One thing we [5:20] do know is that we are shifting into what's called an El Nino year. And there have been [5:25] discussions of this in the past and people have followed along. But what happens during El Nino [5:29] years is we get this extra boost of heat in the water that [5:33] translates into our atmosphere and it usually pushes our temperatures overall for the planet [5:38] higher. So that is one thing. And then that shifts our weather patterns a little bit more. But what [5:43] we also know is that when you add more heat to this atmosphere, it's like a boiling pot of water, [5:48] right? And so things get more turbulent. And when we have more rain events, when they do actually [5:55] trigger, there's more precipitation for them to come down. And when we get these heat events, [6:00] it pushes to higher levels. And that's what we're experiencing right now. [6:03] And that will continue in the 40 seconds we have left. I want to ask you about these floods [6:08] in Hawaii that seem to be really unusual. What can you attribute that to? [6:12] Well, one way we've looked at that is the water temperatures. These are islands and the storms [6:19] are coming off of the water and the water around the islands right now is higher than usual. And [6:25] there is a climate change fingerprint in that also. And we can look at that through what we [6:29] call attribution science and we can tease out that role of climate change in those water temperatures. [6:34] So it's adding more fuel and more moisture for these storms. So it's adding an extra little boost [6:40] to the already wet pattern that was setting up. Bernadette Woods-Plackey with Climate Central, [6:45] thank you so much for joining us. Thanks for having me. [6:48] Support journalism you trust. Support PBS News. [7:01] Donate now or even better, start a monthly contribution today.