Climate change is unearthing archaeological discoveries, while also threatening them

NPR's Danielle Kurtzleben speaks with Jørgen Hollesen, a Senior Researcher at the National Museum of Denmark, about how climate change is impacting the study of archaeology.

DANIELLE KURTZLEBEN, HOST: Earlier this summer, Europeans stumbled across ancient mammoth skeletons and rotting Nazi warships nestled in the riverbeds of the Rhine and Danube rivers. The discovery sparked much excitement from archaeologists, but there is a twist here. They discovered these finds because of climate change. This phenomenon is something that Jan (ph) Hollesen pays close attention to. He's a senior researcher of climate change and archaeology at the National Museum of Denmark, and he joins me now. Welcome to ALL THINGS CONSIDERED. JORGEN HOLLESEN: Thank you. KURTZLEBEN: So this is a fascinating phenomenon. Help me understand it more deeply. In what ways is climate change affecting the study of archaeology? HOLLESEN: Climate change is affecting archaeology in many ways because the preservation of archaeological sites and remains are really dependent on stable environmental conditions, both above ground but also below ground. KURTZLEBEN: I'm really curious about this, though, 'cause you have something very harmful to the Earth, harmful to some of these sites, but it's also causing new discoveries to be made. So how do you square those two? HOLLESEN: Yeah. Basically, we can see, for example, this summer where we have these droughts in all of Europe, they create some conditions in which, like, threats become more severe. So yeah, we see things coming out of rivers, but at the same time, we lack water in most European soils. So all of the things, all the remains that are still buried are losing the water, which are actually the most important thing that preserves them. KURTZLEBEN: Yeah. And as that water dries and stops preserving things, is there a time pressure then to examine these sites? What's that like? HOLLESEN: It's quite difficult actually because you could say the possibility of finding well-preserved sites, finding new, fantastic things, that that possibility is slowly decreasing with every drought that we have, every dry summer. So it makes it more difficult to find things. KURTZLEBEN: To what degree are archaeologists figuring out new best practices and sharing them with each other, like, saying, OK, if you have a new site, here's how you document it quickly, here's how you protect it? HOLLESEN: For example, in Norway, where a lot of things are melting out of small snow patches, people are walking around in the mountains during the summer and looking for things. But in many other places, it's pure luck that you find something. In many mountain regions, no one is coming. So you need to set up with people looking. In Norway, they do it, some places in the U.S., but there's many mountain regions around the world where no one is really looking out. KURTZLEBEN: Do you have an example of a discovery where archaeologists have really had to work quickly to preserve it? HOLLESEN: Yeah. Just recently, I actually talked to journalists from Peru who told me the story about these mummies that were found up in the Andes, where it was pure luck that somebody went there, and then they saw this girl sticking out of the ice, partly frozen out. And they had to cut her out of the ice and bring her back to the nearest city. So that was pure luck that it was found. KURTZLEBEN: Right. You've also written about how climate change is directly destroying archaeological sites via things like wildfires. Can you tell me more about how that's happening? HOLLESEN: Yeah. Whenever there's a wildfire, the heat from the flames could destroy many different things like masonry. And below ground, the heat could also affect the remains that are buried. And at the same time, the damage from the machines that are putting out the fire - there's many possibilities of the remains being deteriorated by the fire and the way we are handling the fire. KURTZLEBEN: Do you have any specific examples of sites that you think are particularly endangered by climate change right now? HOLLESEN: Yeah. I worked a lot in the Arctic, for example, in Greenland, and here we see the permafrost is melting, and there's a lot of fantastic archaeological materials stored in that big freezer you have up there. A lot of really well-preserved artifacts are melting out of the permafrost and degrading. So it's like when you take out some meat from your freezer, it's - the bacteria starts to eat it, and then you have to eat it quite fast before it's degraded. So that's happening in all of the Arctic at the moment. KURTZLEBEN: Jan Hollesen is senior researcher at the National Museum of Denmark. Thank you so much for talking to us. HOLLESEN: You're welcome. 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