Sea level rise
Sea level rise will be one of the most catastrophic impacts of climate change. Yet State and Federal governments are failing to seriously grapple with the problem, basing their policy on expected sea-level rises only half the height of those that scientists say we should take into account for planning purposes. We are working to educate the public on threat of sea level rise and campaigning for governments to take the full range of scientific pinion into account.
Download the Climate Centre primer on sea level rise here
Read "Coastal studies experts: “For coastal management purposes, a [sea level] rise of 7 feet (2 meters) should be utilized for planning major infrastructure” here.
Check the Ozcoast website
Find out about the Port Philip Rising walk
The Facts
Around the world, sea levels rise and fall with the planet's average temperature. As temperature rises, the oceans expand and the polar glaciers melt.
During the last ice age 20,000 years ago temperatures were 5 degrees cooler and sea levels 120 metres lower. If human emissions continue along their current path, global temperatures will be 5 degrees warmer, enough to eventually melt all the polar ice caps and push sea levels 70 metres higher than today.
Even the common target of limiting the temperature increase to 2 degrees will likely increase the sea level by 15–30 metres, but these processes can take hundreds of years. Little is known about the total amount of possible sea-level rise in equilibrium (in the long run when all the imbalances are worked through the climate system) with a given amount of global warming. This is because the melting of ice sheets is slow, even when temperature rises rapidly. As a consequence, current predictions of sea-level rise for the next century consider only the amount of ice sheet melt that will occur until that time, not the total amount of ice sheet melting that will occur over millennia.
However a new paleoclimate record reveals a systematic equilibrium relationship between global temperature and CO2 concentrations and sea-level changes over the last five glacial cycles. Projection of this relationship to today's CO2 concentrations results in a sea-level at 25 (+/-5) metres above the present. This is in close agreement with independent sea-level data from the Middle Pliocene epoch, 3-3.5 million years ago, when atmospheric CO2 concentrations were similar to the present-day value. (http://www.sciencecentric.com/news/article.php?q=09062103-study-document...)
The immediate question is how much is the sea level likely to rise this century. The view of the 2007 IPCC report of about a half-metre rise by 2100 is now too conservative. The general scientific view is now for a rise of 1–2 metres this century, but higher levels of 4-5 metres cannot be excluded, because it it is difficult to predict accurately how fast the huge polar ice sheets will respond to global warming.
For example, some recent research said 2 metres of SLR was upper bound of how much ice could physically be lost from Greenland and Antarctica this century, but this was based on assumption that all ice shelves would remain intact, but some are very vulnerable and already on the edge of being lost.
Earth scientists Mark Siddall and Michael Kaplan say Greenland's glacial slab is entering into a temperature range at which it is becoming "particularly vulnerable" to fast-track melting.
Recent research examining the paleoclimate record shows sea level rises of 3 metres in 50 years due to the rapid melting of ice sheets 120,000 years ago.(http://news.nationalgeographic.com/news/2009/04/090415-sea-levels-catast...)
Will Steffen's (ANU) 2009 report published by Department of Climate Change says that:
• Sea-level rise now 3 mm per year 1993-2003
• Greenland over the past 15 years has changed from being approximately in balance to now losing ice at a rate of 200 billion tonnes per year or greater
• A recent analysis shows warming of about 0.1C per decade over the West Antarctica region over the last half century, attributed in part to changes in sea surface temperature
• Sea‑level rise larger than the 0.5–1.0 m range – perhaps towards 1.5 m (i.e. at the upper range of the statistical projection of Rahmstorf 2007) – cannot be ruled out. There is still considerable uncertainty surrounding estimates of future sea‑level rise. Nearly all of these uncertainties, however, operate in one direction, towards higher rather than lower estimates.
• One of the more dramatic consequences of modest increases in sea level is the disproportionately large increase in the frequency of extreme sea‑level events associated with high tides and storm surges. A 0.5 m rise in mean sea‑level could cause such extreme events to occur hundreds of times more frequently by the end of the century (ACE CRC 2008; Figure 9); an event that now happens once every hundred years would be likely to occur two or three times per year.
On average, the coast line retreats 100 metres for every 1 metre of sea level rise. The Insurance Council says 425,000 Australian addresses less than 4 metres above sea level and within 3km of shoreline are “vulnerable” this century. Already houses and property in Australia are being abandoned.
Much of our infrastructure and many of the world's largest cities are on the coast and huge river deltas are densely-populated farming lands. Climate scientist prof. Konrad Steffen says "A one-meter sea-level rise by 2100... will affect up to 600 million people.” And Sir Nicholas Stern says rising sea-levels will result in forced migrations: “You'd see hundreds of millions people, probably billions of people who would have to move and (probably) cause conflict… around the world (for) decades or centuries.”
Background
'Sea-level Rise: a post-IPCC update' authored by John Church, John Hunter, Neil White and Kurt Lambeck.
www.acecrc.org.au/uploaded/117/797655_16br01_slr_080911.pdf
Notes by Prof. Will Steffen for "Coast to Coast" conference in darwin in August 2008 (attached)
http://www.radionz.co.nz/news/national/2008/08/19/12436e172785
Study documents close relationship between past warming and sea-level rise
http://www.sciencecentric.com/news/article.php?q=09062103-study-document...
Managing our coastal zone in a changing climate: the time to act is now - House Standing Committee on Climate Change, Water, Environment and the Arts report on the inquiry into climate change and environmental impacts on coastal communities.
http://www.aph.gov.au/house/committee/ccwea/coastalzone/report.htm
Coastal development all at sea over climate
http://business.theage.com.au/business/coastal-development-all-at-sea-ov...
Sea rise 'will exceed forecast'
http://www.theage.com.au/environment/sea-rise-will-exceed-forecast-20090...
Nile Delta: 'We are going underwater. The sea will conquer our lands'
http://www.guardian.co.uk/environment/2009/aug/21/climate-change-nile-fl...
Planning for a flood
http://www.theage.com.au/opinion/planning-for-a-flood-20080928-4pnm.html...
Premature climate change ruling creates planning uncertainty
http://www.abc.net.au/news/stories/2008/08/08/2328274.htm
Seaside landowners draw battle line in the sand
http://www.theage.com.au/national/seaside-landowners-draw-battle-line-in...
Victorian coastal strategy all at sea as fears rise over compo claims
http://www.theage.com.au/national/coastal-strategy-all-at-sea-as-fears-r...
Sea levels to swamp Melbourne
http://www.news.com.au/heraldsun/story/0,21985,24145473-2862,00.html
Sea surges could uproot millions in Nigeria megacity
http://www.reuters.com/article/environmentNews/idUSTRE4AI74G20081119
Canal estates banned as sea levels rise
http://www.theage.com.au/national/canal-estates-banned-as-sea-levels-ris...
Animation
http://www.youtube.com/watch?v=TRa_yq8238g&NR=1
The tipping of the iceberg
http://gristmill.grist.org/story/2008/9/5/81346/60150
Greenland icesheet could melt faster
http://www.theage.com.au/world/greenland-icesheet-could-melt-faster-2008...
Sea level rise limited to two metres
http://environment.newscientist.com/channel/earth/climate-change/dn14671...
Bangladesh is set to disappear under the waves by the end of the century
http://www.independent.co.uk/news/world/asia/bangladesh-is-set-to-disapp...
Greenland melt could see huge sea-level rises
http://environment.newscientist.com/channel/earth/climate-change/mg19926...
Massive Canadian Arctic ice shelf breaks away
http://environment.newscientist.com/channel/earth/climate-change/dn14656...
Sea level rises could far exceed IPCC estimates
http://environment.newscientist.com/channel/earth/climate-change/dn14634...
Greenland ice could fuel severe U.S. sea level rise
http://www.reuters.com/article/environmentNews/idUSTRE54Q4SY20090527
Fossil corals show catastrophic sea-level rise?
http://news.nationalgeographic.com/news/2009/04/090415-sea-levels-catast...
Scientists to issue stark warning over dramatic new sea level figures
http://www.guardian.co.uk/science/2009/mar/08/climate-change-flooding
