Sea level is rising: get out of the way!

Sea level 1

Post by Dr. Claire Mellett

In April this year The Geological Society of America and American Geophysical Union joined together to hold the first Penrose/Chapman conference in Texas, USA, under the theme of; Coastal processes and environments under sea-level rise and changing climate: science to inform management. The meeting’s main objective was to raise awareness of the vulnerability of coastal environments to climate and sea-level change and to bridge the gap between science and policy to ensure informed management of the coastal environment. The meeting brought together 80 scientists (including myself) from around the world to discuss the impacts of sea-level rise, climate change, storms and human activity on the coast.

The meeting kicked off with a number of talks looking at records of past sea level. In the past sea-level rise was not linear and there was some degree of natural variability. However, recent rates of sea-level rise are higher than they have been during the last 2000 years. Whilst globally sea-level is currently rising (eustatic), the effect of this rise on the coast varies locally depending on whether the land is rising or falling (isostatic). In the Gulf of Mexico, lowering of the land (subsidence) due to the extraction of oil, gas and water, sediment loading and sediment compaction means that in this area the coast is experiencing even higher rates of sea-level rise making it more vulnerable to the impacts of storms. Here human activity is exasperating the impact of sea-level rise on the coast and billions of dollars are spent trying to protect or repair infrastructure in these low lying areas. The question facing policy makers now is will the economy be able to sustainably support such investment in coastal protection in the future?

Galveston, Texas

Whilst sea-level rise is a major threat to the future of coastal environments, a number of talks highlighted other environmental variables of equal importance. Of these, variations in sediment supply appeared the most significant. In areas where high amounts of sediment are being delivered to the coast, the coast may be able to keep up or even grow despite rising sea-levels. However, in many places humans are interfering with the sediment budget by damning rivers (e.g. Yangtze River, China) or nourishing beaches (e.g. The Netherlands). The meeting highlighted the delicate relationship between sea-level and sediment supply in determining how a coast will respond.

As the meeting drew to close, we were working towards a consensus based on the best available science to present to governments and policy makers outlining the biggest challenges for coastal environments in the future. My personal interpretation of this consensus is that sea-level rise and the impact of climate change at the coast are not something to worry about in the future but something that is happening now. I feel the perception that sea-level rise will slowly encroach the coast at a snail’s pace is misguided. A more realistic view when trying to visualise the impacts of sea-level rise is to think of episodic events such as storm surges and hurricanes which have instantaneous and devastating effects on the coast (and economy). It is therefore important to recognise that in order to secure a sustainable future at the coast, society must learn to adapt to (or get out the way of) rising sea levels.

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