2011-04-07 09:12:29Impacts of Sea Level Rise


I am collecting here some of the most plausible and likely impacts of sea level rise.

I am quite happy for anyone else to write the article - I am busy with a backlog of articles due to my recent illness, so time is a problem.  I will of course contribute as much as I can.


In response to a comment by John, I wrote this:

Impacts of Sea Level Rise

In regions formerly covered by perennial ice, waves, swell and surges will be more energetic.

As sea levels rise, islands and coastal regions made of loose or granular materials and / or permafrost will likely be eroded away.

Materials eroded into the sea will contribute their own volume to total sea level rise.

Land undermined by rising seas may collapse suddenly, causing tsunamis.

Land subtly undermined by rising seas may cause sea defences to collapse suddenly, causing rapid inundation.

Saline intrusion into aquifers will reduce potable water supplies.

Much coastal agricultural land will be submerged or turned to salt-marsh.

The housing needs of populations moving inland will conflict with the need to bring lands under cultivation to feed them.

Areas currently inland will switch rapidly to a maritime climate, most especially if formerly contiguous lands separate into archipelagos.


Sea level rise can lead to increased loss of, not just land-based ice, but land as a material.  These effects are positive feedbacks to further sea level rise.


A study by Mikhail Anisimov and Vladimir Tumskoy of the New Siberian Islands shows how past variations in sea level have altered both the regional climate and the geography.

"During the warming periods of the end of the Late Pleistocene (Raunis, Bolling and Allerod climatic stages) the area of the New Siberian Islands still presented one continental land, which is indicated by dating of the mammoth tusk from Bennetta Island (12.5 kyr BP).

The decrease of climate continentality and increased humidity in the end of the Late Pleistocene resulted in a sharp intensification of thermokarst processes. The accumulation of deposits with high ice content on land was replaced by their melting. On Novaya Sibir Island, a horizontally bedding organic interlayer with an age of 11050±60 (GIN-11246à) overlaps a cast along the ice wedges. On Novaya Sibir Island, there is also a date of 10750±100 years BP (GIN-11247à) obtained from an interlayer of allchthonous peat filling a thermokarst basin. Intensification of solifluction and thermal erosion belongs approximately to this time. There are similar datings from Bol. Lyakhovskii Island.

"The available data on the Novosibirskie Islands indicate synchronous climatic changes in the territory of the eastern Arctic shelf. These changes were of a complicated rhythmic character determined not only by temperature fluctuations, but also by climate changing from continental to marine due to sea transgression."

Anisimov, Mikhail A.. Arctic and Antarctic Research Institute.
Tumskoy, Vladimir E.. Moscow State University, Faculty of Geology.
32nd Annual Arctic Workshop Abstracts
March 14-16, 2002
INSTAAR, University of Colorado at Boulder



Arctic communities are already being impacted by permafrost melt.  Sea level rise exacerbates the problem.  There is a wealth of data on this impact:

"COPENHAGEN, Dec 13 , 2009 (IPS) - The Inuit people who live in and around the Arctic are among the worst victims of global warming, and scientists are now turning to their experience and indigenous knowledge to understand the staggering effects of climate change."



"A decrease in sea ice had increased the fetch of wind and wave size, making travel in small boats more dangerous, affecting the hunting of other marine mammals.

Kivalina's sand and gravel island is held together by beach grass, and at one time, permanently frozen ground. Sea ice used to form sooner and protect against winter storms but a longer ice-free season has meant acres lost to erosion."


"Thawing permafrost in the Arctic has damaged houses, roads, airports and pipelines, and caused landscape erosion, slope instability, and landslides. Local coastal losses to erosion of up to 100 feet per year have been observed in some locations in the Siberian, Alaskan and Canadian Arctic.
In Shishmaref, Alaska, a small Inuit village in the Chukchi Sea, seven houses have had to be relocated, three have fallen into the sea, and engineers predict that the entire village of 600 houses could disappear into the sea within the next few decades. Shishmaref's airport runway has almost been met by rising seawater, and its fuel tank farm, which seven years ago was 300 feet from the edge of a seaside bluff, is now only 35 feet from the bluff. The town dump, which has seawater within 8 feet of it, could pollute the nearby marine environment for years if inundated. Advancing seawater has contaminated Shishmaref's drinking water supply."



"There is evidence for a series of adverse impacts on polar coasts, although warmer conditions in high latitudes can have positive effects, such as longer tourist seasons and improved navigability (see Chapter 15, Section Traditional knowledge also points to widespread coastal change across the North American Arctic from the Northwest Territories, Yukon and Alaska in the west to Nunavut in the east (Fox, 2003). Reduced sea-ice cover means a greater potential for wave generation where the coast is exposed (Johannessen et al., 2002; Forbes, 2005; Kont et al., 2007). Moreover, relative sea-level rise on low-relief, easily eroded, shores leads to rapid retreat, accentuated by melting of permafrost that binds coastal sediments, warmer ground temperatures, enhanced thaw, and subsidence associated with the melting of massive ground ice, as recorded at sites in Arctic Canada (Forbes et al., 2004b; Manson et al., 2006), northern USA (Smith, 2002b; Lestak et al., 2004) and northern Russia (Koreysha et al., 2002; Nikiforov et al., 2003; Ogorodov, 2003). Mid-latitude coasts with seasonal sea ice may also respond to reduced ice cover; ice extent has diminished over recent decades in the Bering and Baltic Seas (ARAG, 1999; Jevrejeva et al., 2004) and possibly in the Gulf of St. Lawrence (Forbes et al., 2002)."

IPCC AR4 WGII Chapter 6: 6.2.5 Observed effects of climate change on coastal systems




"NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100
Study underestimates impacts with conservative assumptions"



Most of my research in this area has been Arctic-focused.  I will try to find data of wider applicability.

Please discuss.