In a groundbreaking climate change study, scientists have found that by neglecting to include the melting of Antarctica, we have vastly underestimated the potential for sea level rise over the next 80 years — and beyond.
The most widely cited estimate of around three feet by 2100 includes sea level rise from thermal expansion (water expands when it warms) and the melting of smaller glaciers. It includes minimal contributions from Greenland and Antarctica.
Instead, this study published in the journal Nature suggests that we should actually double that forecast when we include melting in Antarctica: approximately six feet of sea level rise by 2100. Just as alarming is the projection that Antarctica by itself could add 50 feet of sea level rise by 2500.
What does that even look like?
The 50-foot estimate is hard to imagine. The study essentially concludes that we could alter the face of the Earth over the next 100 to 500 years.
In the study’s projection for 2500, almost the entire state of Delaware would disappear. Much of Manhattan and Brooklyn would be reduced to just slivers of their current selves. The southern coast of Florida would end north of Lake Okeechobee. California’s Central Valley would flood from Modesto to Colusa, and the state capital of Sacramento would be entirely under water. And this says nothing about the millions — billions? — of people who could be displaced around the globe.
It’s a little easier to picture the 2100 projection, which, if this study is correct, would significantly change coastlines in the United States.
Each of these maps was created by the research team at Climate Central. You can explore more coastlines in the interactive viewer. Climate Central used the highest resolution elevation maps available to create these projections. The researchers take into account the mitigating effects of levees, under the assumption that all levees will be able to withstand the pressure of rising seas (despite the fact that only 8 percent of the monitored levees in the United States are considered in “acceptable” condition).
The outcomes range from dire in places such as Miami and New Orleans to avoidable with mitigation strategies in Washington, D.C. Most important to remember when scanning these images is that they still do not include the potentially significant sea level rise from Greenland.
These sea level rise projections were created using the IPCC’s “business as usual” scenario, though there is certainly a caveat to this assumption. It seems unlikely we will be able to maintain everything that comes along with the business as usual scenario: high population growth, little improvement in energy efficiency, no policies to mitigate greenhouse gas emissions and a continued, heavy reliance on fossil fuels.
However, none of the scenarios — low or high emissions — take into account things that are not well-understood, such as the effect of melting permafrost, which in itself has the ability to inject large amounts of greenhouse gas into the atmosphere.
The portrait it paints is a worst-case scenario for how our planet could look if we continue today’s actions and policies unabated — or if we have simply underestimated how much greenhouse gas is entering the atmosphere. Either way, it’s an important potential outcome to examine, if only to serve as motivation to reduce fossil fuel emissions sooner rather than later.