Sea Level Rise is Far Worse Than Previously Thought

Rising levels of greenhouse gasses are increasing global temperatures and this is causing sea levels to rise. Global warming causes sea levels to rise by melting ice sheets, glaciers, and sea ice; it also causes water to warm and expand. Sea-level rise and resultant flooding may be the greatest challenge facing humanity. Scientists agree that sea levels will rise and much of the most recent research suggests that this rise will be larger and faster than originally thought.

Rising seas are expected to inundate many of the world’s greatest cities, including Manhattan, London, Shanghai, Hamburg, Bangkok, Jakarta, Mumbai, Manila, and Buenos Aires. Tidal floods interfere with transportation, inundate roads, destroy homes, damage cars, kill forests, and poison wells with salt. Moreover, the high seas interfere with stormwater drainage.

The seas are, on average, around 9 inches higher than they were before the Industrial Revolution. We now have 408 parts per million of CO2 in the atmosphere, and it is growing. Our current trajectory translates to 120-190 feet of sea level rise over the long term.

Sea Level Rise: More and Faster

The world is getting warmer and this heat is causing more thermal expansion. Sea level rise is also caused by the melting of the world’s two largest ice sheets, on Greenland and West Antarctica, as well as mountain glaciers worldwide. Most studies suggest that sea levels will rise by about three feet, but these studies have not adequately measured the contribution of melting ice from Greenland and the Antarctic ice sheet. Greenland alone is losing 215 gigatons of ice per year; that is equivalent in weight to 100 times all the cars on the planet.

As reported by Angela Fritz in the Washington Post, a new study published in the Journal Nature shows that on its own, the melting of the Antarctic ice sheet could double sea level rise.

Using the IPCC’s “Business as Usual” scenario, oceans could rise by almost 2 meters or more than six feet by the end of the century. By 2500, we could see the sea level rise by more than 13 meters (42 feet). Such an increase in sea levels will have civilization changing impacts all around the world including the US. By 2100, Miami and New Orleans will be under water. By 2500, states like Delaware would be almost entirely submerged as would the southern coast of Florida, California’s Central Valley, Sacramento, San Francisco Bay, Boston, Washington DC and much of Manhattan and Brooklyn.

An ABC News article corroborates this view, citing research from renowned climate scientist James Hansen which indicates a doubling of the speed at which sea level rise is occurring.

A study from the U.S. Geological Survey found that half of the U.S. coastline is at high or very high risk of impacts due to sea level rise.  Around the world, the majority of human habitation is concentrated along coastlines. This means that billions of people could potentially be displaced.

“Accelerated sea level rise is real, and it’s ongoing, and it’s not something we should doubt,” said John Fasullo, a climate scientist at the National Center for Atmospheric Research in Boulder, Colorado.

A study led by Rutgers University shows that sea levels are rising faster than at any time in the past 2,800 years. The study examines historical sea level rise and shows that our oceans are rising at an ever increasing rate. To illustrate what this means in practical terms, look at the rate of flooding in Annapolis, Maryland. The tide gauge at Annapolis recorded 32 days of flooding from 1955 to 1964, while that number spiked to 394 days in the decade from 2005 to 2014.

As reported by Don Jergler in the Insurance Journal at the annual RIMS conference last spring, an official with the National Oceanic and Atmospheric Administration (NOAA) indicated that sea levels could rise by much more than originally anticipated and much faster. The most recent data translates to sea level rises that are far worse than IPCC predictions. This new data suggests that sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and far sooner than current projections.

By 2050, a total of 26 major US cities may find themselves struggling to manage rising seas.

Present Day Reality

Sea level rise is not just some abstract future possibility; it is already happening. As explored in a study published in Environmental Research Letters, there are at least five reef islands in the Pacific that are already inundated, and they serve as a warning for the world. Five Solomon Islands are gone, washing away the homes of the people who lived there. At least six more islands are severely eroded. While the global average annual sea level rise is about 3 mm per year, in the Solomon Islands, the rate of increase is around 7-10 mm per year since 1993.

By 2100, 13 million people will be displaced in the U.S. alone. As reported in the Green Market Oracle, flooding is also a modern-day problem in the US. Residents of Chesapeake Bay’s Tangier Island are expected to become climate refugees in a few decades. The village of Kivalina, in northwestern Alaska, will be underwater by the year 2025. A total of more than 180 villages are already feeling the impacts of rising seas. The Yupik community of Newtok is expected to be completely underwater by 2017. Rising seas are already forcing people out of their homes in the bayous of Louisiana, about 80 miles southwest of New Orleans. The Isle de Jean Charles is disappearing into the rising waters of the Gulf of Mexico, forcing many of its residents to flee.

As explored by Justin Gillis in a New York Times article, sea level rise is already impacting U.S. coastal areas. He lists dozens of places where we are already seeing the impact of rising sea levels; this includes Fort Lauderdale and the only road to Tybee Island, GA.

“Once impacts become noticeable, they’re going to be upon you quickly,” said William V. Sweet, a NOAA scientist. “The [flooding] trends are all very clear. They’re going up, and they’re going up in many of these areas in an accelerating fashion.”

“It’s not a hundred years off — it’s now.” Andrea Dutton, a climate scientist at the University of Florida and one of the world’s leading experts on rising seas said, “It’s a slow, gradual attack, but it threatens the safety and security of the United States…We’re Living It”

The West Coast of Oregon and California can expect to suffer the worst impacts of rising seas. Along the East Coast, NOAA scientists say that many communities have already, or will soon, pass a threshold where flooding starts to happen much more often. In southern Louisiana and the entire Chesapeake Bay region, including Norfolk, flooding is expected to be severe.

Seas Will Keep Rising

Even if we engage in serious global emissions reduction efforts, sea level rise is baked into the system. As reviewed in a study of past sea level changes published in Science, coastal communities may face rises of at least six meters even if we limit global warming to 2C.

A rise of at least 15 or 20 feet has already become inevitable. This data pours cold water on the hope that mitigation efforts alone could stop the seas from rising. It is clear that we will also need to invest in adaptation to manage inevitable sea level rises.

The economic costs of sea level rise are already staggering, and these costs will continue to accrue. The only sane response to scientific predictions about sea level rise to aggressively engage in both mitigation and adaption efforts.

Sea-level rise could be far worse than the dire scientific predictions cited above, as these studies do not take into account the massive amount of GHGs that could be unleashed by melting permafrost.

Together, the data convincingly shows that we need to do what we can to advance both mitigation and adaptation efforts. This means we need to curb fossil fuel usage and other man-made GHGs. We also need to invest massively in adaptation efforts to prepare for inevitable sea level rise.


Image credit: NASA

Richard Matthews
Richard Matthews
Richard Matthews is a consultant, eco-entrepreneur, sustainable investor, and writer. He is the owner of THE GREEN MARKET, one of the Web’s most comprehensive resources on the business of the environment. He is also the author of numerous articles on sustainable positioning, green investing, enviro-politics, and eco-economics.

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