“The picture that emerges is very concerning,” adds Ariadne Angulo, who co-chairs the amphibian specialist group at the International Union for Conservation of Nature. Humans inadvertently spread Bd around the world, and can easily do the same for other wildlife diseases. “In a complex and globalized world where disease is easily moved across different ecosystems, the potential to wreak havoc is considerable,” Angulo adds.

But the world is changing so quickly that scientists and conservationists are struggling to make sense of it. They’re having to rush species that once seemed stable into captive arks before they go extinct in the wild. They’re watching as years of work are undone by natural disasters, such as Australia’s recent bushfires, that are occurring on once-unimaginable scales. And more often than not, they have to deal with these problems using incomplete information. The natural world is in bad shape, but how bad? Which bits are most in need of help? The urgency of the world’s biodiversity crisis is growing, but the data about that crisis are as imperfect as ever.

Many disagreements have sprung from that tension between knowing that there’s a problem and not knowing its extent. Other researchers have chastised the authors of the recent study that estimated how many amphibian species have been affected by Bd for using weak evidence and poor data-handling practices that have made it hard to replicate the results. (The critique, and the authors’ response, is set to be published soon.) Another prominent study which claimed that 55 percent of the ocean is fished was slammed for looking at the seas at too low a resolution; a different team, using the same data, calculated a figure of just 4 percent. A third study which looked at changes in North American bird populations was criticized for overplaying a splashy stat—3 billion fewer birds since 1970—over subtler details, some positive and some negative. A much-hyped narrative about a looming insect apocalypse has been questioned because there’s only long-term data for a vanishingly small proportion of insect species.

Read: The alarming case of the missing insects

Scientists, on average, tend to be cautious types. They’re less likely to cry wolf, and more likely to say that the evidence suggests that a wolf is around but we’d ideally like to see more data before coming to firm conclusions. But in many cases, the problem is not that they haven’t done the work to get data. It’s that they have no option for collecting more.

Consider El Copé. Here was a team of experts who had funding for many years of surveys, and who knew that Bd might hit their region and so could start doing censuses before that event. And yet, they could barely collect enough information on the local snakes to analyze because, well, fieldwork is hard. It is difficult enough to assess obvious animals like elephants and giraffes, let alone smaller, rarer, well-camouflaged species, like snakes. Zipkin’s solution was to offer probabilities instead of hard, media-friendly numbers. “It’s hard for us to pinpoint how many species there were before and after, and there’s a wide range of possible numbers,” Zipkin says. Instead “we can talk about the probability of decline. That’s the best we’ll ever be doing, because there’s no scenario where we could just collect more data. We now have probably the strongest evidence that we’ll ever have that there are cascading effects.”

Is that enough? Will an 85 percent chance that snakes have been hit resonate as strongly as, say, the alleged disappearance of 3 billion birds? “This is a very common problem for conservation,” adds Lips. “You know that something is wrong and you have a gut feeling that things are much reduced, but to have the robust scientific data that you need to support your claim and get policy change … that can be very difficult.”

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