Sunday, July 1, 2012
Visited a missing Hawaiian beach lately?
Get used to it.
With the lack of aggressive action on climate change over the past decades, continued sea level rise is now essentially baked in, ocean and climate scientists are saying.
A study in the journal “Nature – Climate Change,”a new study argues that there’s little we can do now to prevent dramatic sea level rise.
Even with an aggressive program of controlling greenhouse gas emissions, sea levels will continue to rise based on our past misdeeds, write researchers Michiel Schaeffer, William Hare, Stefan Rahmstorf and Martin Vermeer. Schaeffer is from the Netherlands, much of which is below sea level, where accurate modeling of sea conditions is taken seriously. He works with the Environmental Systems Analysis Group of Wageningen University and Research Centre in Holland. His co-authors are climate researchers from Germany and Finland.
Their message: A 50% chance that sea levels will be a couple of feet (75-80 centimeters) higher than 2000 levels by 2100, if we can hold warming below 2 degrees Centigrade. And it will keep rising, they argue, to more than 8 feet by 2300.
We would not even recognize the coastlines of our great-great-grandkids . The islands would be significantly smaller as the ocean washes much higher on their shoulders.
“Halting (sea level rise) within a few centuries is likely to be achieved only with the large-scale deployment of CO2 removal efforts, for example, combining large-scale bioenergy systems with carbon capture and storage,” write Schaeffer and his team.
The globe needs to not only stop rising CO2 levels, but to drive CO2 production to negative levels, if sea level rise is to be slowed. Without that level of effort, imagine even larger rise.
The authors concede that the science of sea level change is still evolving and that there are many uncertainties—but they point out that current estimates are more likely to be low than high—thus, it could be worse than they now estimate.
“Physics-based models attempting to predict the combined contributions from thermal expansion, glaciers and ice sheets are not yet mature and underestimate the (sea level rise) observed in past decades,” they write.
There’s a fair amount of other alarming science out there. One piece is that sea level rise isn’t uniform across the oceans, and one group of researchers suggests that the northern Atlantic coast of the North America will see higher rise than other areas. It attributes this to salinity, currents, changing gravity and the Earth’s rotation.
“(Sea Level Rise) rate increases in this northeast hotspot were ~3-4 times higher than the global average,” write the authors of a paper, “Hotspotof accelerated sea-lkevel rise on the Atlantic Coast of North America.”
Add storm surge, and they predict serious vulnerability for harbors and coastal cities.
It doesn’t help that the popular media are screwing up the story. One big component of global sea level predictions is whether and how quickly the Greenland glaciers melt. Two recent pieces on the same day, May 3, 2012, had these contradictory headlines.
If you only read the headlines, you’d think those stories were contradictory. They’re not. The first one just says the glaciers are melting scary fast, but just not at breakneck speed. It says they’re not melting fast enough for 6 feet of sea level rise in the next 88 years—just 3 feet.
Well, three feet is enough to erase virtually every beach we now know in Hawai`i, to put much of coastal Honolulu underwater, to push Hilo and Hanalei Bays deep inland, to have significant impacts on coastal Kihei.
Have you visited a missing beach in Hawai`i?
If you visit the shore at all, you know the scenario. Where there used to be sand, there are rocks. Where there used to be palm trees and heliotropes, there’s water. Where kids used to build sand castles, there’s ancient sandstone washed by waves.
And that's just what's happening now.
Here is University of Hawai`i coastal geologist Chip Fletcher's famous progression of what happens to Waikiki under three feet of sea level rise--think street surfing.
© Jan TenBruggencate 2012
Posted by Jan T at 9:10 AM