Climate Change Is Drying Up Islands
That honeymoon hike through tropical forests of Maui or Tahiti may become a memory of the past.
That romantic hike through a lush tropical island may be an experience for today's couples instead of their kids or grandkids. Climate researchers say that small islands in the Caribbean, Pacific and Atlantic will be drying out as the world's temperatures rise and rainfall patterns shift toward the middle and end of this century.
Some small islands will become wetter, but the majority -- 73 percent -- will become drier. That means less freshwater for local residents, agricultural products that sustain the islands' economies, and vegetation and wildlife that depend on the island's unique ecosystems.
"It's going to be harder to grow stuff because there's not going to be enough water," said Kristopher Karnauskas, assistant professor of atmospheric and oceanic sciences at the University of Colorado Boulder.
"The small island doesn't have a large catchment area," he said. "Unless they are really well developed, they are relying on rainfall."
Karnasuskas and colleagues at the Woods Hole Oceanographic Institution and University of Arizona published their findings today in the journal Nature Climate Change. Their study is a projection of what might happen if current trends in global temperature and rainfall continue.
In the 2013 report by the International Panel on Climate Change (IPCC), scientists used global climate models to predict shifts in rainfall and temperature over the world's continents. But the land mass of many small islands is too small for these models to come up with an accurate prediction.
Karnauskas substituted the known evaporation rates over land to fill in the blanks in in the climate equation for these islands, which have a total population of 18 million people.
"If you could magically transport your self into a climate model to where you ought to find an island in French Polynesia, there's only open ocean," he said. "We pretend that there is a land surface and use principles of how evaporation works and calculate aridity."
By 2090, the calculations show that islands with a population of about 9 million people will become 20 percent dryer, while another 6 million will experience 40 to 60 percent less fresh water.
Karnauskas predicts the hardest hit will be the islands of the Lesser Antilles (from the U.S. Virgin Islands south and west to Aruba), the Azores and Canary Islands off Spain and several remote islands in the South Pacific (French Polynesia, Easter Island and Robinson Crusoe Island) and the Marshall Islands.
The Hawaiian Islands are a mixed bag, according to the report's calculations, which call for a slight increase in arid conditions by 2050, followed by slightly wetter conditions from 2050 to 2090.
"Tropical rainfall might just expand northward enough to bring moisture to Hawaii," he said.
However some experts say the rainfall patterns across the world's oceans will be difficult to predict as the world warms.
"The elephant in the room here is the change in precipitation, specifically, the uncertainty in the direction of change," said Alessandra Giannini, a climate researcher at Columbia University in an e-mail to Discovery News.
"The authors correctly point out that there is some coherence in the large-scale pattern, with deep tropical islands trending towards wet, and sub-tropical islands such as Easter Island trending towards dry. But the largest uncertainty in projections remains model disagreement in how physical processes responsible for precipitation are represented, and how they may be changing as the planet warms."
Giannini studies climate change and drought in the Caribbean basin. Previous climate studies predicted that the entire region, including Cuba, Jamaica, Hispaniola (Haiti/Dominican Republic) and Puerto Rico, will become drier.
The region's poverty will make it harder for island residents to adapt by finding new sources of water, according to Marisa Escobar, a senior scientist at the Stockholm Environment Institute.
"It will be more difficult for islands," Escobar told Discovery News. "On continental settings, you could create infrastructure that transports water from one place to another. But some small island have very little in terms of watersheds and reservoirs."
A drone captured this view of Mili Atoll, in the Republic of the Marshall Islands.
You've heard a lot about how human-driven climate change will lead to hotter temperatures, cause sea levels to rise and make storms more intense. But it's projected to have plenty of other unpleasant and even disastrous effects as well. Here are 10 of them. Scientists believe that rising temperatures will lead to increased evaporation of the Great Lakes' water, and precipitation won't make up the difference. That means we're likely to see declines in water levels over the next century, and one study predicts they may drop as much as 8 feet.
Thanks to climate change, jumbo-sized ragweed plants will spew out more pollen for a longer, more miserable allergy season.
By altering the wild environment, climate change makes it easier for newly mutated microbes to jump between species, and it's likely that as a result, diseases will emerge and spread across the globe even more rapidly.
A recent Nature article reported that male Australian central bearded dragons have been growing female genitalia because of rising temperatures, a phenomenon that had not previously been observed in that species.
Rising sea levels are wiping out beaches all over the world already. Importing fresh sand and building them up again is only a temporary solution. To make matters worse, there's currently a sand shortage, due to demand from fracking, glass and cement making.
Bark beetles are eating old growth forests, because the winters aren't cold enough to kill them off. So more trees like this American Elm will die.
Warmer temperatures mean there will be more water vapor trapped in the atmosphere, leading to more lightning. A University of California-Berkeley study predicts that lightning strikes will increase by about 12 percent for every degree Celsius gained.
Wine grape harvests are being hurt. Regions that have historically supplied the world’s best wine will no longer be hospitable climates to grow wine grapes, according to research by the Environmental Defense Fund and others.
Coffee flavor depends upon really narrow conditions of temperature and moisture, and climate change is going to wreak havoc with that. Worse yet, as coffee growing regions become warmer, pests that couldn't survive in the past will ravage the crops. This is already being seen in Costa Rica, India and Ethiopia, which have experienced sharp declines in crop yields.
Scientists say that as ice sheets and glaciers melt, the weight that's removed from the Earth's crust changes the stresses upon volcanoes. That unloading effect can trigger eruptions.