Small Islands Face Evaporation Crisis

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When it comes to climate change, the largest quantifiable effects might soon show up in the tiniest places.

Though they may be hard to find on your average map, small island nations are scattered all over the globe, from tourist hotspots in the Caribbean to the seemingly unpronounceable archipelagos of the Maldives. But they’re not simply exotic travel destinations—millions of people populate these islands and call them home.

The global sea level has risen by eight inches over the last century, and scientists predict it will rise another one to four feet by the year 2100. More recent findings doubled those predictions to account for the dematerialization of Antarctica if carbon emissions aren’t significantly reduced. This presents a pretty obvious problem for any area proximal to the ocean, let alone tiny rocks surrounded by it entirely.

As it turns out, rising sea levels aren’t necessarily the only threat climate change poses to these nations. According to a study published in Nature Climate Change, 73 percent of small islands will become significantly drier in years to come in result from a number of factors, namely evaporation, that will reduce their supply of fresh water.

Due to the scope of global climate models, which reliably predict rainfall and evaporation on large continents, small islands were left out of the picture as they are simply too tiny for these models to take into account.

Dr. Kristopher Karnauskas, study author and assistant professor of atmospheric and oceanic sciences at the University of Colorado-Boulder, explains why these islands are so easily overlooked.

“What climate models do is take the whole world and cut it up into little boxes, which are kind of like pixels,” Karnauskas tells BTRtoday. “If the pixels are bigger than a small island, then climate models are not able to resolve a small island nation. They’re just a small dot within a larger pixel, so they have no idea what’s really going on.”

Tabulating rainfall is relatively easy to measure regardless of land size, but the limitations of global models can’t project evaporation on the islands, which is critical in measuring fresh water levels. Knowing only one of these is problematic in that it paints an incomplete picture.

“It’s sort of like knowing the score at the end of a baseball game, but only for one team,” Karnauskas says. “You don’t know who won.”

The study’s ability to calculate island evaporation revealed that nearly three-quarters of the 80 islands studied would experience increased aridity in coming years. Though the range of aridity between islands is fairly large, the study’s models project islands with larger populations to dry out more than others.

According to Karnauskas, that particular finding is coincidental, but nonetheless troubling.

“It would have been a happier story if we found the places that were going to dry had no humans living on them,” he says. “That would be fine. Unfortunately, it’s kind of the other way around.”

Another concern the study wasn’t able to address is the projected population growth on many of the islands. Even if the projections revealed no change in aridity or fresh water, the increase in population would in turn increase fresh water stress, given the same amount of water being shared by more people.

Fresh water is a big deal on small islands because it’s more or less all they have to use. It’s easy for someone living in a developed country such as the United States to take fresh water for granted given its abundant availability, even in times of drought or during other water issues.

“If you want a drink of water [in the U.S.], it’s not that hard to get,” Karnauskas says. “We have it for agriculture, in the Midwest and across the Great Plains. But these islands are places surrounded by a salty ocean. They can’t use that for agriculture, they can’t drink it, so really all they have to work with is the balance of what falls as rain and what gets sucked back up into the atmosphere by evaporation.”

Both sea level rise and increasing aridity pose serious threats to island nations, though the question of which problem bears more significance depends on a given island’s vulnerabilities. However, the subject of rising sea levels has long been on the radar of these nations and of the minds of people discussing climate change across the globe.

“I just try to understand what the implications of climate change are going to be so that we know, and so that people in positions to negotiate on behalf of nations can’t claim they didn’t know,” he explains.

Given the lack of information surrounding the nature of evaporation on these islands, Karnauskas hopes the findings of his study serve to empower those countries to understand how climate change can affect them in an unexpected way.

“The worst thing to me would be not knowing that this additional climate change-related threat is there, and not be able to plan for adaptation or how to manage your water supply differently,” he says. “As long as they know this is coming, there’s probably some conservation efforts that can be implemented in terms of how you store water, allow the use of it, where it goes, who it goes to, and how you capture it.”

Karnauskas doesn’t represent an advocacy group or proclaim himself an activist beyond his scientific work, but he admits to seeing the paradox of small island nations that have contributed so little to climate change bearing some of the largest and most immediate burdens of it. Still, the information now available is paramount to the adaptation and survival of these island nations, no matter how much cruel irony their developing problems present.

“If it were just a few decades ago, we could be talking about human populations that were completely out of contact with the rest of the world,” he says. “And here we would be, going about our business with the developed world pretty unequivocally causing climate change without even being aware of the effects.”