The Witness King Tides project: the Problems Thereof

Dr John Hunter1

1Antarctic Climate & Ecosystems Cooperative Research Centre, Hobart, Australia


The “Witness King Tides” (“WKT”) project originated in New South Wales, Australia, and is now internationally active in a number of regions ( WKT is a citizen-science project which aims to illustrate the impact of future sea-level rise by photographing potentially vulnerable coastlines at the time of highest astronomical tide each year. There are benefits and disbenefits of such an approach, one of the disbenefits being that the results may be so contaminated by storm surges that they bear little relation to what is likely to happen under sea-level rise. The viability of WKT is investigated using the GESLA-2 global high-resolution (i.e. with one hour of shorter sampling) tide-gauge database ( which, provided suitable sea-level data at 586 locations (47 within Australia), which had at least 20 years of data. The results indicate regions of Australia and elsewhere in the world where WKT is an appropriate tool, and other regions where it quite definitely isn’t. Alternatives to WKT will be discussed.


John Hunter is an oceanographer working in an emeritus position at the Antarctic Climate & Ecosystems Cooperative Research Centre, which is based in the University of Tasmania. His current interests are the sea-level rise induced by climate change, and the response of Antarctic ice shelf cavities to global warming. His interest in sea-level rise was initially stimulated in the mid-1990s by his work (with others) on the historic sea-level mark at the Isle of the Dead, Port Arthur, which indicated where sea level was in 1841. This was one of the first such marks struck anywhere in the world for the scientific investigation of sea level. Recent work has involved investigations of sea-level rise in Australia, the U.S., and in the Indian Ocean and Pacific regions, and the way in which this rise increases the frequency and likelihood of flooding events. He was the original developer of the “Canute” sea-level rise decision-support tool (see In recent years he developed a method of deriving sea-level planning allowances based on projections of sea-level rise and present storm-tides; the techniques has been used in Tasmania, Victoria and more widely around Australia, New Zealand and Canada. He has a keen interest in seeing that the science of climate change is accurately communicated, not distorted by the so-called “climate skeptics” and is appropriately incorporated into public policy.