How much will global sea levels rise by 2100? Here are some estimates (all accessed online on June 23,2018):
"Sea levels are rising faster now than in the previous century, and could rise between 50cm to 1.5 metres [20 inches to 4.9 feet] by 2100 ." Skeptical Science, How much will sea levels rise in the 21st Century?
"Recent projections range from 0.2 meters to 2.0 meters (0.66 to 6.6 feet)." NASA, Understanding Sea Level Projections
"If we stay on our current trajectory of fossil-fuel use, median global average sea-level rise could be 4 feet 9 inches (about 1.5 meters) by 2100..." Quartz, Land where 153 million people live may be underwater by 2100*
"Under high greenhouse gas emissions, [rise in global sea level] increases from 79 to 146 cm [2.6 feet to 4.8 feet]. Without protective measures, revised median RSL projections would by 2100 submerge land currently home to 153 million people, an increase of 44 million." Kopp et al, 2017, Evolving Understanding of Antarctic Ice‐Sheet Physics and Ambiguity in Probabilistic Sea‐Level Projections
The high end of the above estimates assume minimal progress in reducing GHG emissions this century, which seems unlikely given current trends**. But smaller increases in global sea levels would still be a problem for coast-dwelling flora and fauna (including humans). So what can we do about it?
Landscape architect Kristina Hill has some ideas. In an interview with Yale 360, Hill notes that in most cases the best response to sea level rise is not the extreme one of building walls or abandoning the coast, but of creating “hybrid edges" that blend natural ecosystems and human-made infrastructure to help cities and towns adjust to rising tides. More specifically:
- Use more wetlands, sand dunes, horizontal levies and beaches to protect against sea encroachment.
- Build more resilient sewage treatment plants and roadways
- Re-grade muddy river landscape so people wouldn’t be exposed to sewage stranded on the banks at high tide
- In some places build houses on piled foundations and design the houses so that they can accept damage and be rebuilt so long as the pilings are designed to last a hundred years.
- Use wet ponds, rain gardens,and wetlands around housing to absorb extra storm water when needed.
Orrin Pilkey, professor emeritus of earth and ocean sciences at Duke University, agrees with Hill that in most cases rising sea levels do not have to entail a retreat from the coast. Pilkey suggests governments adopt a “menu of resiliency” to help coast-dwellers adapt to rising sea levels, through creative civil engineering, landscape architecture, landscape design, structure design, and neighborhood outreach. For instance, structures could be designed to accommodate storm surges by putting all mechanical and safety systems on the roof.
It's a start.
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* The Quartz quote is actually based on the Kopp et al study. It was included to illustrate how science news often misrepresents research findings - I suspect to ramp up the fear factor. In this case, Kopp et al's projected sea level rise was based on a "high emissions" scenario, not "our current trajectory", and the submerged coast estimate was based on the assumption of no "protective measures".
**These trends include: dematerialization of production, sustainable intensification of agriculture (allowing more land to revert to forest), reforestation, dematerialization of consumption (“peak stuff”), spread of renewables, declining carbon intensity, ongoing energy efficiency improvements, growing market for electric cars, decoupling between economic growth and emissions, declining car ownership in cities, and slowing global population growth – to name a few.
References and Links:
https://www.enr.com/articles/42487-special-report-how-engineers-are-preparing-for-sea-level-rise
Kopp, R. E., DeConto, R. M., Bader, D. A., Hay, C. C., Horton, R. M., Kulp, S. , Oppenheimer, M. , Pollard, D. and Strauss, B. H. (2017), Evolving Understanding of Antarctic Ice‐Sheet Physics and Ambiguity in Probabilistic Sea‐Level Projections. Earth's Future, 5: 1217-1233. doi:10.1002/2017EF000663