PCE calls for action on sea level rise – expert reaction

New Zealand needs to do more to prepare for the consequences of rising sea levels, warns the Parliamentary Commissioner for the Environment in a new report.

Coastal flooding in March 2014. Credit NASA
Coastal flooding in March 2014. Credit NASA

In the report, titled, Preparing New Zealand for rising seas: Certainty and Uncertainty, Commissioner Dr Jan Wright outlines the risks posed by rising sea levels, including flooding and erosion.

The report concludes by putting forward eight recommendations including: developing a National Policy Statement on addressing sea level rise; building consistency in the projections of sea level rise, mapping data and community engagement guidelines provided to local councils; and establishing a working group to assess and prepare for the economic and fiscal implications of sea level rise.

“We must plan for sea level rise, but there is time to do it carefully”, Dr Wright said in media release. “There are a few cases where action is required soon, but in most cases it is more important to do it well than to rush.”

The new report follows an earlier report from the commissioner laying out the science underpinning the projected sea level rise for the future.

Sir Peter Gluckman, the Prime Minister’s Chief Science Advisor, released a statement welcoming the new report, noting that the document “makes the science on sea level rise accessible and highly relevant to New Zealanders.”

You can listen to audio from the Commissioner’s launch of the report below. Detailed land elevation maps of areas vulnerable to sea level rise are available here.

The Science Media Centre collected the following expert commentary.

Dr Richard Levy, Programme Leader – Past Antarctic Climate, Paleontology and Environmental Change, GNS Science, comments: 

“The Commissioner’s report does a great job of highlighting the issue of sea level rise and there is lots of information for us to think about.

“It is a really good summary of the general impacts of sea level rise, and the maps combining projected sea level rise with LiDAR data are useful.  However this is just scratching the surface of the in terms of the actual regional effect.

“Sea level rise won’t be uniform across the surface of the Earth or even around New Zealand – it actually varies quite dramatically depending on where you are. New Zealand is a very tectonically active region; parts of New Zealand are going up and parts are going down. The east coast of the North Island is in particular moving downwards. When you are living on a costal region that is subsiding – moving downwards –  that will cause local sea level rise to greater than if you were living on land that was moving up.

“We need work on this to get better idea of how vertical land movement will affect sea level rise at the local and regional level – so that policy makers will have that information at hand to help in their planning.

“We are also working on reducing the uncertainty in the global sea level rise projections by improving our understanding around how the Antarctic ice sheet will respond to warming.

“Now we need to get on with this more detailed work to reduce uncertainty and answer some of the questions that I am sure local councils and people who have houses in vulnerable areas are asking.”

Dr Paul Denys, Lecturer in Sea Level Studies, School of Surveying, University of Otago, comments:

“I would agree and endorse the commissioner’s recommendations.  They are written in an easily understood way but unfortunately I don’t think they will necessarily have the impact on central government that they should.  The time scales outlined are too long for politicians to take seriously and I fear these exceedingly important issues will be put in the too hard basket.  Possibly one way to gather traction would be to have a better idea of the fiscal implications i.e. Recommendation 8 should be carried out before rather than in conjunction with the other Recommendations.

“As stated in the document, we do have time to implement good planning, it is not necessary to rush.  But this in itself will make it too easy for central government to ignore forward planning.  Central government needs a clear message from the whole of New Zealand.

“Should the public be concerned?  Certainly, but there is probably little people can do to resolve the problem as individuals.  It is therefore essential to have a nationally coordinated response with uniform standards across the country, but tailored to individual regional problems.

“There is one technical area that I don’t think has been adequately addressed and that is robust uncertainties need to be applied to the DEM.  (The Recommendation regarding SLR projections states that the uncertainties need to be estimated, and this should also be applied to the DEM).  It is incorrect to state that the LIDAR techniques measures elevations (with respect to MSL).  LIDAR measures heights (with respect to an ellipsoid) and must be converted to elevations using a geoid model. This is not mentioned in the PCE report (and does not need to be) but I can find no mention of how this was done (if at all) in the NIWA (2015b) report.  The change from heights to elevations may have been done in the individual data sets, but I do not have access to this information.  For some of the LIDAR data sets I have some knowledge of, it was not carried out adequately.

“Why is this important?  Having this done correctly and transparently can make a significant difference to low lying land.  It is possible to have water running uphill!  To do this a geoid model needs to be applied and the current model developed by LINZ has a (national) precision of ±6-8 cm.  Combine this with the precision of LIDAR ±10-15cm and the precision of your elevations is in the order of ±12-17cm.  The three sigma (99% CI) is now approaching the 50cm elevation contours of the maps produced in the report. (Note that LINZ are now computing a new more accurate model due for release in 2016)”

Dr Stephen Flood, Postdoctoral Fellow, Climate Change Research Institute, Victoria University Wellington, comments:

“The Commissioner’s recommendations are considered and based on a thorough analysis of relevant science and policy.

“As outlined in the scientific literature and this PCE report, the public should be concerned about climate change induced sea level rise and the associated impacts on coastal flooding, erosion, and groundwater.

“The Commissioner’s final recommendation to appoint a working group to prepare for the economic and fiscal implications of sea level rise is crucial. It is also critical that the funding be made available for local councils to generate the information necessary at a local scale to bolster planning and management decisions that consider the impacts of sea level rise.

“The report highlights that hasty decisions in relation to coastal adaptation actions are unwise. However, it is vital that this call for appropriate information gathering and community consultation is not construed as an excuse for inaction in the area of coastal management.

“Natural heritage in New Zealand’s coastal communities is a valuable asset. Although natural heritage is not explicitly considered in this report it is important that the impacts of sea level rise on natural coastal heritage be considered and accounted for in any planning or management decisions.

“The recommendations to engage in standardised processes for council engagement with coastal communities as well as ensuring scientific data is standardised and engaged with consistently and transparently is welcomed.”

Prof Martin Manning, Climate Change Research Institute, Victoria University of Wellington, comments:

“The Parliamentary Commissioner for the Environment’s report, on how sea level rise will affect New Zealand, now sets out a framework for responses that clearly go beyond just saying that a problem is coming. One of the key aspects of this is that central government needs to provide a much clearer sense of direction and guidance to local government. Until that is done, local governments are just faced with continual dispute and litigation and so are inclined to defer dealing with the problem.

“In particular, the report makes a very clear statement that the Minister of Finance now needs to address the economic and fiscal risks that can be caused by sea level rise.”