Through both sunny days and torrential storms, sailors cutting through the waters around New Zealand and Antarctica faithfully recorded the weather they encountered, building up a treasure trove of data. Over a century later, scientists are digging through these maritime records for insights about the past and future of the region’s climate — and they need the public’s help.

Knowing what the weather was up to in the past can help scientists calibrate climate models like the ones they use to predict how weather conditions are likely to change as global temperatures continue to rise. Sailors traveling around New Zealand from the late 1800s to the mid-1900s to trade goods, hunt whales, or explore Antarctica kept logs about the water and air temperatures, air pressure, sea ice, and wind. “Those logbooks are an absolutely massive source of weather data that we can use to improve our historical record of what we know about New Zealand’s climate and the climate of the surrounding oceans,” says Petra Pearce, a climate scientist with New Zealand’s National Institute of Water and Atmospheric Research (NIWA).

“Those logbooks are an absolutely massive source of weather data.”

The trouble is that these logbooks are handwritten, which means they’re hard for humans to read and even harder for a computer make out. So Pearce and a team of researchers turned to the public for help transcribing these logbooks. The project is called Southern Weather Discovery, and it launched in October 2018. Since then, volunteers have transcribed more than 200 logbooks from early 20th century merchant ships, Pearce says. “People do really want to be involved in science.”

The website says they’re around 89 percent of the way through the transcriptions, but Pearce says not to be fooled by that stat. This is a long-term project, and there are many more logbooks to photograph, process, and upload for people to analyze. Next on the list are logs from whaling vessels, which Pearce is particularly excited about because those ships went right down to Antarctica. “We don’t have really any data for Antarctica because, obviously, there was no one there 100 years ago, apart from the odd exploration,” she says.

The Verge spoke with Pearce about bad handwriting, the aurora, and expeditions that never made it back from Antarctica.

This interview has been lightly edited for clarity and brevity.

What’s your favorite thing that you’ve learned during this process?

One of the most interesting things was reading the logbooks from Robert Falcon Scott’s 1911 to 1912 expedition to the South Pole. Scott was part of the British Antarctic expedition, and they sailed down there in a race for the South Pole. They got beaten by the Norwegians, and on their way back from the South Pole, tragically, Scott and the few of his men that were with him at the time died from exposure. But they were taking measurements of temperature and barometric pressure and things like that right up until they died on the ice. You could see their observations getting more and more sporadic over the last days of their journey before they died, and it was very humbling to think they kept going, even in the face of horrible circumstances. They kept going and kept taking these observations. They didn’t know what would happen with them. And to think that over 100 years later, we’re now using these observations for research to understand what was going on and what may happen in the future — that’s huge.

Why are you asking people to transcribe weather data in logbook entries?

All of these logbooks that we have are handwritten, so they are very difficult to have read by a computer. Technology’s not at a point yet where that can be automated, although the research is underway into how we can automate reading that handwriting. You can have the computer give you what it thinks these handwritten numbers are. But you need to trust that, you need to know that that’s right. And we haven’t gotten to the point where we trust that completely yet, so it’s an ongoing process.

“It’s a really big human effort.”

At the moment, it’s a really big human effort, and that’s why we started Southern Weather Discovery — to get people from around the world involved. They can basically help us to transcribe this weather data that we really need to undertake our research. We have this big database of all of our climate data from these logbooks — and other sources as well — that we can basically put into climate models to refine the image of that weather map going back in time.

How does the transcription process work?

We have this logbook page, and it’s got a lot of information on it, different columns and rows. That’s quite a lot for someone to look at. They’ll say, “Oh, I can’t transcribe that. That’s way too much.” So we crop little sections of these logbook pages out, put them onto the website, and someone can come onto the website and type in the numbers they see. Sometimes the numbers are a little bit difficult to decipher. It’s really old-style, curly handwriting. So we have some help guides to say, “Does your number look like this? It might be a 7, or it might be a 4.”

We also have 10 different people transcribe the same image for quality control. That way, if someone types in a wrong number, that wrong number doesn’t get propagated through to the global database. People can undertake as little or as much as they want. We’ve got people who have come in, and they’ve done just a little bit, and they’re like, “Okay cool, that’s not for me.” But there are other people who, even six months later, are regularly taking part, and that’s really cool to see.

What do you do with that data once people transcribe it?

We download a huge amount of data from the website and go through a quality control process to weed out the incorrect data that people may have keyed. Then we put it all back together, and we eventually upload those now-typed logbook data into global databases. They will directly go into improving the data coverage for this part of the world and helping us to understand what was going on in terms of climate back in the day.

We’re still sifting through a lot of the data that’s been keyed so far. There have been some pretty interesting things we’ve seen looking at some of the notes in there — like observations of icebergs quite far north in the warmer waters where you wouldn’t normally experience them. Observations of wildlife and whales, the aurora (the southern lights), and absolutely horrible storms that these ships were traveling through. You can imagine a lot of them were steamships, but a lot of them were also sailing ships that were fighting through some horrendous conditions and still taking their observations religiously multiple times a day.

How close are you to being finished?

It’s a moving target. We’ve had a lot of data transcribed already on the website. But behind the scenes, we are still processing the logbooks, and we upload new sets of data every so often. It’s a long-term project. It’s not just something that’s going to end when we finish the data that we’ve got on there at the moment. We would love people to come and help. If people have these old logbooks in their houses, that’s also something that’s really valuable. If they wanted to let us know they have that and we can do something with that data, that’s amazing as well. We’ve had a couple of people actually call us up and say, “Hey! I have all this data from 100 years ago — do you want it?” And we’re like, “Yes, thank you! That’d be great!” It’s really cool some of the things that come out of the woodwork. And it’s really cool to engage with the public in this process rather than just publish a scientific article about it. We’re actually engaging people and helping them to understand why we do what we do.