+64 27 462 4872 editor@mahurangi.org.nz

The Mahurangi Magazine

Select Page

Avoid ‘dredging’ with access code

by 15 Feb 2010Action plan planning, Dredging, Sea-level rise0 comments

Science as a Contact Sport cover

Schneider on Salinger: ‘Managers are a dime a dozen, world-class scientists very rare. Maybe the wrong guy at NIWA got sacked.’ image National Geographic

Dredging, by definition, is a dirty business. Which is why the draft working paper addressing the issue uses the code access. While many will see this as inexcusable political correctness, it is actually entirely sound to define the objective, rather than just one means of achieving that object.

And while dredging may occur in the Mahurangi River, there are environmental and economic limitations. It is important to quantify the current access and to forecast changes that are occurring.

The focus, understandably given the science on it, has been squarely on the elevated sediment accumulation rate. But the science is also telling us that the rate of sea level rise globally has recently doubled, to an estimated 3.32 mm per year.

NASA Goddard Institute for Space Studies director James Hansen, who has been subjected to clumsy gagging attempts—reminiscent of those suffered by Dr Jim Salinger before his sacking—suggests that sea level rise will double at periods, possibly as short as 10 years. If Hansen’s contention that sea level rise is unlikely to be linear is correct, concern for access could swiftly be drowned by concern about inundation.

With the measuring of sea level rise now a matter of extreme urgency, as is measuring anthropogenic global warming generally, river access studies are set to be much better informed. But this is not to suggest that some strategic dredging is unwarranted. Best that it be well-informed.

This is where ‘weaving science and community’ in the Mahurangi gets seriously challenging.

Time to set dogma aside, settle down and read the science.


Hot Topic: Global Warming and the Future of New Zealand, Gareth Renowden, AUT Media, 2007

The Discovery of Global Warming, Spencer Weart, Harvard University Press 2008, Online December 2009

The Weather Makers: The History and Future Impact of Climate Change, Tim Flannery, 2006

Poles Apart: Beyond the Shouting, Who’s Right About Climate Change, Gareth Morgan and John McCrystal, Random House, 2009

Science as a Contact Sport: Inside the Battle to Save Earth’s Climate, Stephen H Schneider, National Geographic, 2009