I admit it. In my heart of hearts, I'm hoping for the best. Those scenarios of climate change we see splashed across the newspapers and magazines include a wide range of possibilities, and I keep my fingers crossed that we'll end up closer to the best case. But just three weeks ago the best case got a lot worse. A group of climate scientists meeting in Copenhagen announced that sea level very likely is going to rise almost twice as much as we thought. The old estimates were not so old—they were issued in 2007, when the Intergovernmental Panel on Climate Change (or IPCC) came out with their latest summary report, which suggested that sea level would likely rise somewhere between seven inches and two feet by the year 2100. Problem was, in 2007 the IPCC had a limitation they had to work around—basically, the models of the time couldn't crunch all the numbers necessary to interpret how the ice sheets would react to a warming climate. Ultimately, it's ice sheets grounded on land that melt and pour new water into the oceans, causing them to rise. Now the models of how glaciers will melt have gotten better, and we've actually watched glaciers melt more than we thought they would in the past two years. That's what makes the news about sea level worse. The new, better estimates say that the water will rise at least between one-and-a-half and three feet by the year 2100. Some say six feet is not out of the question. Three feet means around 600 million people concentrated in coastal cities and islands will be affected by flooding, and millions of those will become climate refugees heading for higher ground. This is not in the distant future, by the way—it would happen as children playing on earth today, mine and yours included, grow into middle and old age. The economic and societal implications are staggering. But there are also some equally staggering ecological costs that the world will suffer if we don't consciously think about how to head them off. Sea level rise of three feet would cause the disappearance of entire ecosystems from the face of the earth—many of which we have invested considerable energy and money in trying to keep alive. An obvious example is Everglades National Park. This is the third largest park in the lower 48 states. It protects the largest biologically intact area east of the Rocky Mountains, the largest freshwater sawgrass prairie in the United States, and the largest protected mangrove ecosystem in the Western Hemisphere. We as a society and a culture value these things, so much so that Everglades was actually established “not as a scenic showplace but as a biologic marvel,” for the American people, but it didn't stop there. The place is valued by the whole world: it is a World Heritage Site, an International Biosphere Reserve, and a Wetland of International Importance. The superintendent of Everglades explained all this to a congressional subcommittee back in 2007, as he was outlining what to expect from the IPCC estimates of sea level rising between seven inches and two feet. The current estimates of one-and-a-half to three feet, of course, would have even greater consequences for the park. What would a three-foot rise in sea level do to the Everglades?
- Submerge a large portion of it: 60% of the park is less than 3 feet above mean sea level. In fact, a sea level rise of three feet would lop off the southern fifth of Florida.
- Lead already endangered species like panthers, manatees, and alligators towards extinction. The park is home to 69 species that have been listed as threatened or endangered.
- Submerge one of the rarest ecosystems on Earth. The park's ecosystems are unique in the world, because they contain a mixture of South, Central, and North American species.
- Destroy ecosystem services that would affect drinking water for up to five million South Florida residents, and cost millions of dollars in lost local revenues. The park now fuels a large part of the South Florida economy, from the money spent by more than one million people who visit the Everglades each year.