Last month, a Foreign Policy column focused on security issues turned its attention to the cryosphere.
The writer, Sharon Burke, a senior advisor at the New America foundation and former Obama administration official, began by pointing out the “aesthetic pleasure” of the term “cryosphere”:
The word sounds like some kind of secret realm, possibly involving dead people, but it’s really ice, snow, glaciers, and permafrost. The cryosphere is all the frozen places on Earth, or more specifically, all the frozen water on Earth.
There’s just one problem with the magical ice kingdom: It’s melting.
Burke then focused on a new study (the New York Times covered it in late March) about the Antarctic ice sheet, and the implications that could have for the billions who live in places where the waters will rise.
According to the study, published in the journal Nature in March 2016 and called “Contribution of Antarctica to past and future sea-level rise,” the Antarctic ice sheet is melting at a much faster rate than previously thought. This melting ice ends up in the Earth’s oceans, contributing to sea level rise.
The study uses updated modeling, which includes details about rocks and glaciers, to establish projections of future Antarctic ice sheet loss. The authors say that if greenhouse gas emissions continue to grow, the West Antarctic ice sheet will start to break apart by the year 2050. The model includes melting from both below and above the ice sheets, by including the impact from warmer ocean currents underneath ice sheets and warmer temperatures in the atmosphere. The improved model reproduced ancient historical sea levels more accurately than previous models, focusing on a period 125,000 years ago, when the oceans were 20 to 30 feet higher. This success supports the model’s ability to accurately predict future sea levels.
But the Antarctic ice sheet is not the only factor influencing sea level. Sea ice, land glaciers, and permafrost are also melting at a rate that contributes to the disappearance of the cryosphere and contributing to rising oceans.
Sea level rise is a very large problem for the human populations located in the vulnerable coastal zones. The Times article points out that New York, a city founded roughly 400 years ago, is unlikely to remain intact for the next 400 years. Cities like Miami, London, Hong Kong, and Sydney are also likely to feel the rising tides. But the populations in the most danger are those outside in the developing world. Dhaka, the capital of Bangladesh, provides an example. It is one of the most populated cities in the world, with 15 million people, and is located at sea level.
According to the study, the collapse of the Antarctic ice sheet could mean more than three feet of sea level rise, leaving limited alternatives for populations at risk. Costly solutions like sea walls and augmented infrastructure are out of the reach of the poorest cities. This leaves them in the greatest danger, with few options.