A new U.S. Geological Survey study claims most low-lying Pacific atolls will become “uninhabitable by the mid-21st century” because of man-made global warming.
The taxpayer-funded study predicts wave-induced flooding made worse by sea level rise will overwhelm low-lying Pacific atolls, but researchers only get these alarming results by misinterpreting work done by the U.S. Defense Department.
The study claims that on the “basis of current greenhouse gas emission rates, the nonlinear interactions between sea-level rise and wave dynamics over reefs will lead to the annual wave-driven overwash of most atoll islands by the mid-21st century,” which is much earlier than most other estimates.
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“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century,” Curt Storlazzi, a USGS geologist and the study’s lead author, said in a statement.
Researchers specifically looked at Roi-Namur in the Republic of the Marshall Islands, and found the island’s potable water will become too inundated with sea water “within the lifespan of current residents and before 2030” based on the Intergovernmental Panel on Climate Change’s worst-case scenario.
The study found “most of Roi’s land would be flooded annually” by the “2055–2065 time frame” based on the IPCC’s worst-case that also includes a collapse of the Antarctic ice sheet — called “RCP8.5+icesheet collapse.”
But climate scientist Bob Kopp noticed the USGS study relied on sea level rise estimates put together by the Defense Department that don’t represent actual climate scenarios.
“Unfortunately, some of the headline numbers from the paper — how soon the 40 cm threshold will be crossed — are liable to misinterpretation because of the way the authors used some sea-level rise scenarios developed for the Department of Defense,” Kopp wrote in a blog post.
“These scenarios were intended as tools for risk management, not as forecasts of what would be likely under different emissions scenarios,” Kopp wrote, adding “study does not use the [DOD] scenarios as risk management tools; it uses them as though they were forecasts.”
In fact, the sea level rise scenario that results in Roi-Namur becoming “uninhabitable” before 2030 is more than twice what the IPCC predicted in the latest climate assessment.
The IPCC predicted RCP8.5 would yield 0.45 to 0.82 meters of sea level rise by 2100. The USGS study predicted 2 meters of sea level rise by 2100 based on misinterpreted DOD estimates.
“From a sea-level rise perspective, this conclusion is overly pessimistic,” Kopp wrote.
Also, experts are increasingly realizing RCP8.5 is unlikely to come to pass. RCP 8.5 is the IPCC’s “nightmare” scenario, but two University of British Columbia scientists published a study in 2017 that found “RCP8.5 and other ‘business-as-usual scenarios’ consistent with high CO2 forcing from vast future coal combustion are exceptionally unlikely.”
But even then, most of the damages from sea level rise come from wave-driven flooding, typically brought on by storms. Without modeled wave-driven flooding, the USGS’s worst case scenario doesn’t inundate Roi-Namur with seawater until the end of the 21st Century.
Modeling wave height and strength is an extremely difficult endeavor. Much of the wave damages to Roi-Namur, and by extension hundreds of other low-lying islands, comes from storms.
USGS expects global warming to lead to fewer, but stronger, storms in the Pacific. But that’s an assumption, and there’s still a lot of uncertainty about projects of cyclone activity over decades. Cyclones are a complex phenomenon and hard to predict based on just a few variables, like temperature.
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This report, by Michael Bastasch, was cross posted by arrangement with the Daily Caller News Foundation.
