Uncorking East Antarctica yields unstoppable sea-level rise05/05/2014 – The melting of a rather small ice volume on East Antarctica’s shore could trigger a persistent ice discharge into the ocean, resulting in unstoppable sea-level rise for thousands of years to come. This is shown in a study now published in Nature Climate Change by scientists from the Potsdam Institute for Climate Impact Research (PIK). The findings are based on computer simulations of the Antarctic ice flow using improved data of the ground profile underneath the ice sheet. Photo: M. Martin/PIK“East Antarctica’s Wilkes Basin is like a bottle on a slant,” says lead-author Matthias Mengel, “once uncorked, it empties out.” The basin is the largest region of marine ice on rocky ground in East Antarctica. Currently a rim of ice at the coast holds the ice behind in place: like a cork holding back the content of a bottle. While the air over Antarctica remains cold, warming oceans can cause ice loss on the coast. Ice melting could make this relatively small cork disappear – once lost, this would trigger a long term sea-level rise of 300-400 centimeters. “The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork,” says co-author Anders Levermann. “Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk,” says Levermann, who is head of PIK’s research area Global Adaptation Strategies and a lead-author of the sea-level change chapter of the most recent scientific assessment report by the Intergovernmental Panel on Climate Change, IPCC. This report, published in late September, projects Antarctica’s total sea level contribution to be up to 16 centimeters within this century. “If half of that ice loss occurred in the ice-cork region, then the discharge would begin. We have probably overestimated the stability of East Antarctica so far,” says Levermann.Emitting greenhouse-gases could start uncontrollable ice-melt
Indeed it is. Blown.
If you’ve missed the other segments of our interview with Glaciologist Eric Rignot – do not, repeat, do not, miss this one.
Rignot was a co-author of the “holy shit moment” paper from last spring, showing that large areas of the West Antarctic Ice sheet are now in “irreversible decline”.
That news made for one of my most harrowing videos of the last year, which you can, and should view if you have not – below the fold.
I’m keeping these clips from our interviews minimally edited – I want the raw video to speak for itself to current readers, and to historians, who will undoubtedly understand all too well why we were peeling our jaws off the floor after this one.
SAN FRANCISCO –By 2050, a majority of U.S. coastal areas are likely to be threatened by 30 or more days of flooding each year due to dramatically accelerating impacts from sea level rise, according to a study published today in Earth’s Future, a journal of the American Geophysical Union.
Annapolis, Maryland, pictured here in 2012, is one of three major East Coast urban areas already being faced with nuisance flooding in excess of 30 days per year. Credit: Amy McGovern
The new study establishes a frequency-based benchmark for what the authors call “tipping points” for when so-called nuisance flooding—flooding between 0.3 to 0.6 meters (one to two feet) above local high tide—occurs 30 or more times a year. The study used a 0.5 to 1.2 meters (1.5 to four foot) set of recent projections for global sea level rise by year 2100 similar to the rise projections of the Intergovernmental Panel for Climate Change, but also accounting for local factors such as the settlement of land, known as subsidence.
Based on that standard, the team found that these tipping points will be met or exceeded by 2050 at most of the U.S. coastal areas studied, regardless of sea level rise likely to occur this century.According to the study authors,these regional tipping points will be surpassed in the coming decades in areas with more frequent storms, or areas where local sea levels rise more than the standard global projection of 0.5 to 1.2 meters (1.5 to four feet). This also includes coastal areas like Louisiana where subsidence is causing land to sink below sea level.
The new study, presented at a press conference today at the AGU Fall Meeting in San Francisco, used data from NOAA tide gauges to show the annual rate of daily nuisance floods has drastically increased, even accelerating in recent years. This type of flooding is now five to 10 times more likely today than 50 years ago.
“Coastal communities are beginning to experience sunny-day nuisance or urban flooding, much more so than in decades past,” said William Sweet, oceanographer at NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS) in Silver Spring, Maryland, and lead author on the study. “This is sea level rise. Unfortunately, once impacts are noticed, they will become commonplace rather quickly. We find that in 30-40 years even modest projections of global sea level rise – 1.5 feet by 2100 – will increase instances of daily high tide flooding to a point requiring an active, and potentially costly, response and by the end of this century, our projections show that there will be near-daily nuisance flooding in most of the locations that we reviewed.”
The scientists base the projections on NOAA tidal stations where there is a 50-year or greater continuous record. The study does not include the Miami area, as the NOAA tide stations in the area were destroyed by Hurricane Andrew in 1992 and a continuous 50-year data set for the area does not exist.
Based on that criteria, the NOAA team is projecting that Boston; New York City; Philadelphia; Baltimore; Washington, D.C.; Norfolk, Virginia; and Wilmington, North Carolina; all along the Mid-Atlantic coast, will soon make, or are already being forced to make, decisions on how to mitigate these nuisance floods earlier than planned. In the Gulf, NOAA forecasts earlier than anticipated floods for Galveston Bay and Port Isabel, Texas. Along the Pacific coast the earlier impacts will be most visible in the San Diego/La Jolla and San Francisco Bay areas.
Mitigation decisions could range from retreating further inland to coastal fortification or to a combination of “green” infrastructure using both natural resources such as dunes and wetland, along with “gray” man-made infrastructure such as sea walls and redesigned storm water systems.
“As communities across the country become increasingly vulnerable to water inundation and flooding, effective risk management is going to become more heavily reliant on environmental data and analysis,” noted Holly Bamford, NOAA acting assistant secretary for conservation and management. “Businesses, coastal managers, federal, state, and local governments, and non-governmental organizations can use research such as this as another tool as they develop plans to reduce vulnerabilities, adapt to change, and ensure they’re resilient against future events.”
“The importance of this research is that it draws attention to the largely neglected part of the frequency of these events. This frequency distribution includes a hazard level referred to as ‘nuisance’: occasionally costly to clean up, but never catastrophic or perhaps newsworthy,” said Earth’s Future editor Michael Ellis, Head of Climate Change Science at the British Geological Survey in Nottingham, United Kingdom, in accepting the paper for the online journal.
Ellis also observed that “the authors use observational data to drive home the important point that nuisance floods (from inundating seas) will cross a tipping point over the next several decades and significantly earlier than the 2100 date that is generally regarded as a target date for damaging levels of sea-level. The paper also raises the interesting question of what frequency of ‘nuisance’ corresponds to a perception of ‘this is no longer a nuisance but a serious hazard due to its rapidly growing and cumulative impacts’.”