Wednesday, March 14, 2012

Get away from the coast while you can?

An academic study published today by the Institute of Physics (*see my footnote below) called "Modelling sea-level rise impacts on storm surges along US coasts" suggests that rising ocean waters due to global warming is going to be a serious threat to most Americans who live near the sea.

This comes from the paper's abstract:

We find that substantial changes in the frequency of what are now considered extreme water levels may occur even at locations with relatively slow local sea-level rise, when the difference in height between presently common and rare water levels is small. We estimate that, by mid-century, some locations may experience high water levels annually that would qualify today as 'century' (i.e., having a chance of occurrence of 1% annually) extremes. Today's century levels become 'decade' (having a chance of 10% annually) or more frequent events at about a third of the study gauges, and the majority of locations see substantially higher frequency of previously rare storm-driven water heights in the future. These results add support to the need for policy approaches that consider the non-stationarity of extreme events when evaluating risks of adverse climate impacts.

Here are some excerpts from the conclusion of this research:

Through this study we are able to offer a picture of likely changes in the return levels and periods of coastal storm surges in the next decades that, depending on the location, may significantly alter risk assessment related to high water levels and should be considered a relevant result for stakeholders and policy makers involved in coastal infrastructure or environmental protection decisions. Pacific coast locations are most in danger of seeing their historical extremes frequently surpassed in the coming few decades, followed by the Atlantic. Gulf locations appear in least danger of a rapid shift, despite rapid relative sea-level rise, due to the high amplitudes of historical storm extremes, which render the relative effect of sea-level rise small.

This conclusion quotes research which suggests more and worse hurricanes will hit the Gulf coast:

The greater near term risk in the Gulf (as in a large portion of the Atlantic coast) is however the possibility of increasing cyclone intensity (Knutson et al 2010), concerns we do not address here. Our work provides further evidence that conducting risk assessments of coastal flood hazards must account for non-stationary behaviour, driven mainly by rising mean sea-level.

I once spoke with a climate scientist from UC Davis about sea-level rise due to global warming. I was curious how melting polar ice would have that much of an effect on the vast oceans. He explained that melting ice is only a small fraction of the problem. The real issue is due to the fact that warm water takes up more physical space than cold water. This quote is from "A warmer world will have a higher sea=level because as the land and lower atmosphere of the world warm, heat is transferred into the oceans. When materials are heated they expand (thermal expansion). So the heat that is transferred causes sea water to expand, which then results in a rise in sea-level.:
*Here is what the IOP says about itself: "The Institute of Physics is a leading scientific society promoting physics and bringing physicists together for the benefit of all.

"It has a worldwide membership of around 40 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications."

Here is what Wikipedia says about the IOP: "The present day Institute of Physics was formed in 1960 from the merger of the Physical Society of London, founded in 1874, and the Institute of Physics, founded in 1920.

"It is the main professional body for physicists in the United Kingdom and the Republic of Ireland, and grants the professional qualification of Chartered Physicist (CPhys), as well as Chartered Engineer (CEng) as a nominated body of the Engineering Council.

"In addition to this, the IOP provides services to its members including careers advice and professional development. As a part of its mission, the IOP works to engage the public with physics and runs the website, an online guide to physics, and a blog.

"The IOP is prominent in its work in policy and advocacy, lobbying for stronger support for physics in education, research and industry in the UK.

"The IOP's publishing company, IOP Publishing, publishes more than 60 academic titles."

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