Earlier this week, two wildfires started ripping through southern New Mexico within just 24 hours. They had scorched thousands of acres. 1400 structures had been damaged. More than 8000 residents had to evacuate. At least two people were killed.

He was trying to to get away from the fire as fast as he could, you know, but with a with a broken leg and a brace, using a walker, trying to carry what you could. It's heartbreaking to know that he didn't make it again.

'This all happened in just 24 hours and not long after. Severe thunderstorms dumped buckets of rain on the charred area, triggering flash flooding. Talk about whiplash. Elsewhere in the U.S., many cities in the northeast saw days of extreme heat wave earlier than usual. A tropical storm off the Gulf of Mexico churned up storm surge on the south Texas coast. Scientists continue to sound the alarm here. Human caused climate change is making these kind of extreme events more likely. We're already feeling those impacts on the personal level. But what happens when climate chaos starts pitting world governments against each other? My guest today is CNN senior climate writer Laura Patterson. She has the story of how a war over water is already playing out along the US-Mexico border. From CNN. This is one thing. I'm David, right? So Laura, it is absurdly hot in the US this week, and I realize, like warm weather in mid-June is not exactly breaking news. So can you just explain why this heat wave is so noteworthy to people like yourself who follow this stuff so closely?

Sure. Well, it's prolonged, it's expansive, and it's early. So there's this massive heat dome parked over eastern US. Temperatures are pushing upwards of 90 degrees, and these are temperatures that you might expect more in the hottest days of July. So in kind of peak of summer.

Summer is still days away but a big chunk of the U.S. is already hot, is an oven.

But they're happening now much earlier, and the heat is likely to intensify. We're seeing parts of the Midwest to the northeast that could see the longest heatwave they've experienced in decades.

According to the National Weather Service. It has not been this hot for this long. And Pittsburgh in 30 years.

Look at that. And it's also going to be affecting places that don't have AC and where a lot of people don't have AC. So that means they're much more exposed to this heat, which is a really sort of scary thing. And obviously this is not just a US phenomenon. It's happening in lots of parts of the Northern Hemisphere.

At least 41 Jordanians perished as they made their pilgrimage to Mecca, where yesterday they set a new all time high at over 125 degrees.

Hundreds of pilgrims have died in Mecca, where temperatures reached well over 120°F. China, India. Parts of southern Europe, like Greece, have also faced these brutal early heat waves.

And in Greece, at least three tourists lost their lives simply by hiking without enough water or shade.

So it's just a really alarming sign, but not a surprising one, because the science is really clear that as humans keep warming the world, as we keep pushing up temperatures, keep burning planet heating, fossil fuels, heatwaves are only going to get more severe, more prolonged, more frequent. And one of the things that I've been looking at in my reporting is how heat and drought are affecting the relationship between Mexico in the US in an interesting way.

And so what did you find?

So Mexico and the US obviously share a border, and a large part of that border is made up of the Rio Grand. And there is a treaty between the two countries under which they agree to share water resources. So under the terms of this eight year old treaty, the US shares water from the Colorado River and Mexico shares water from the Rio Grand. But Mexico has fallen a really long way behind in its deliveries. So it's supposed to be delivering on these five year cycles, and we're more than four years into the current one, which ends in October 2025, and Mexico's delivered just over a year's worth of water in that time. So obviously it's it's a long way behind, only.

Way behind.

Way behind. And it's causing some serious issue and rhetoric is is getting quite heated.

Okay. So they're well behind on these deliveries. And is it as simple as the planet is hotter, there are more droughts. That means less rain and therefore less water for Mexico to give. Or are there other factors at play here?

Well, it's always complicated when it comes to water. There's always a sort of tangle of complicated factors, and here development has a lot to do with it. So a lot of towns, farms, industry have have popped up either side of the border and that's increasing demands on water. But then you add the climate crisis on top of that, and it just makes everything that much worse. We know that climate change is fueling sort of longer, hotter droughts, longer, more severe heat waves, and that's leading to diminishing water resources. And it's causing a lot of pain in Mexico. So farmers are struggling. Mexico City looks like, you know, potentially could run out of water, have a day zero, potentially even this month according to some. So it is a really kind of fraught, difficult issue. But the pain is on the other side of the border as well.

Obviously, as it stands right now, we're in the fourth year of the treaty, and they have just delivered a little over one year's worth of water. One year's worth of water is 350,000 acre feet to the U.S, which is one third of the flow that comes down the Rio Grande from the Rio Concho.

Is that what destroyed the business here?

That's what destroyed the business here. Because without water we can't grow sugarcane. So?

So Mexico's water deliveries go to Texas and farmers in South Texas are saying, we are really concerned about our future. We don't have enough water. The citrus industry is struggling. The state's sugar industry has been particularly hard hit.

And so a lot of these people that work for us have worked here their entire working career, and it's super difficult to have to tell 500 people that their job won't be here anymore.

Farmer Tudor Allen told my colleague Rosa Flores that the state's only sugar mill closed last February. And the industry is basically dying in Texas. And he firmly blames the lack of Mexican water deliveries for that.

This has occurred under Republican administrations, and it's recurring right now under a Democratic administration. It's the State Department that interprets the treaties for the United States and is responsible for enforcing those treaties and the state.

And there's actually no enforcement mechanism under this treaty. But some Texas politicians are actually calling on the Biden administration to kind of implement punitive measures to basically withhold aid from Mexico until those deliveries are made. And Mexico, some politicians are saying, well, we cannot give you what we do not have.

It's like we just literally don't have any water. How are we going to deliver it?

Right, exactly. So, you know, things are really difficult for us. The Mexican government has said we will fulfill our obligations. We will provide water by the end of October 2025. But it's a huge amount of water to give. So there are real concerns about this.

Sugarcane is the canary in the coal mine. We're the first to go, but there are thousands and thousands of acres of citrus and vegetables cotton, corn, sorghum, sesame, all kinds of crops that are grown down here that require irrigation. And right now, we're out.

So what can be done? It does seem to me like part of the problem, right, is that this treaty is like 80 years old, and it was not written with climate change in mind. So could they just rewrite the thing to take drought into account? Like what do you do?

'You're absolutely right. So yes, this is a decades old treaty. It was based on data from the first half of the 20th century. So it did foresee drought. That's why Mexico is delivering on these five year cycles. The Rio Grande is unpredictable. We've known that for a long time. But what it didn't foresee is these kind of multi-year mega droughts, and that's a real problem. But in terms of like a wholesale renegotiation, it seems really unlikely it would be opening up a bag of worms. And people built reliance on these treaties. Right. So if you think you're going to get a certain amount of water, you set up a town or a farm or an industry, you depend on that. If that then gets taken away, that's that's real pain.

Like the long term planning, this kind of stuff is baked in.

Exactly. There are ways to amend the treaty. So there's a process called the minute process. And both countries agreed to amendments. And there were discussions at the moment about an amendment a minute, which would aim to get Mexico to deliver more regularly, more reliably. So those discussions are carrying on at the moment. And Mexico is actually just elected a climate scientist for president, and she has pledged to prioritize water issues. So there's hope that, you know, there could be kind of negotiations that help smooth relations, help try to make delivery of this water easier. And in the medium term, you know, they're talking about things like drought resilience measures, protecting preserve and conserving water resources. But in the short term, you know, there's not actually a huge amount that they can do is a kind of pray for rain approach. And the rain has actually come now to areas of South Texas and Mexico, which could help replenish these water resources, but it might end up being too much of a good thing with the risk of flooding as rain falls on really parched ground. But experts say anyway, waiting for rain is not a good long term strategy. We can't just keep praying for rain to help alleviate these problems. And I think it really does shine a light on this much bigger issue of how we share these shrinking water resources when the world is just getting hotter and drier.

Yeah. I mean, I was going to say, like even beyond North America, are world governments thinking about how to share water as it becomes more and more of a scarce resource?

I mean, I think it has to be top of mind for governments thinking about how we deal with this, because we do know that climate change is going to be affecting extreme weather like heat and drought.

As if the deadly wildfires in New Mexico weren't destructive enough, now thunderstorms are causing dangerous mudslides and flooding, making a hazardous situation even worse for first responders and, of course, residents at least.

So we're just going to be seeing this huge unpredictability where we might see, you know, massive flooding, rivers bursting their banks one month, the next month. We're seeing these really sort of severe droughts. So thinking about sharing water resources, thinking about how to kind of protect them, how to build in drought resiliency is just going to be so important going forward.

Yeah. And like we see with so much of the climate change discussion, it's how to address some of these problems while not exacerbating already existing inequalities. Laura, really great reporting. Thank you.

Thank you so much.

One thing is a production of CNN Audio. This episode was produced by Paola Ortiz and me, David Rind. Our senior producer is Faiz Jamil. Our supervising producer is Greg Peppers. Matt Dempsey is our production manager. Dan Dzula is our technical director. And Steve Lickteig is the executive producer of CNN Audio. We get support from Haley Thomas, Alex Manasseri, Robert Mathers, John Dianora, Leni Steinhart, Jamus Andrest, Nichole Pesaru, and Lisa Namerow. Special thanks to Katie Hinman. We'll be back on Wednesday and make sure you're following the show. It's a big week for us. CNN is hosting the first presidential debate down in Atlanta. I will be there to cover it all. So stay tuned for all that. I'll talk to you later.