Royal Society of New Zealand paper highlights new research around sea level rise

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Emerging Issues – Sea Level Rise

New research on the melting of ice sheets is helping coastal managers understand how to plan for future sea level rise, says a paper released by the Royal Society of New Zealand.

In its paper the Royal Society says warmer climates have always resulted in rising oceans, but how much rise and how rapid that rise will be are critical questions for an island nation like New Zealand.

Professor Keith Hunter, the Society’s Vice President of Physical Sciences who contributed to the paper, says researchers are starting to be able to estimate the amount of rise that we should expect to see over this century and beyond. But he says these projections of future sea level rise depend upon the future melting of ice sheets, which is poorly known.

“The uncertain knowledge about ice sheet behaviour is the key reason why IPCC projections in 2007 did not state upper bounds for sea level rise. Similarly, Ministry for the Environment guidance in 2008 wisely left open the question of any upper limit on sea level rise.”

The paper states that some early scientific work into the effect of a warming climate on ice sheets in Greenland and Antarctica suggested that many metres of sea level rise could occur within a century. However, it says few scientists now consider that such rates are possible.

In contrast, recent estimates of sea level rise are greater than those given by the IPCC in their last report. Between those two bounds, researchers are not yet able to make precise estimates of the probability of a given ocean rise within a given timescale.

Professor Hunter says the majority of New Zealand’s large towns and cities are on our coasts.

“Sea level rise will compound the hazards from erosion, flooding, storms, and waves to a degree that is currently hard to quantify.”

The paper, called ‘Sea Level Rise’, has been produced by the Royal Society of New Zealand as one of a series that seeks to inform the public on emerging and sometimes contentious issues around science and technology.