Rising sea levels have major implications for coastal gardens. Yesterday’s king tide gave us the perfect opportunity to see what will be commonplace by 2050. One corner of the world that is experiencing greater than average sea level rises is north eastern Australia.

Even if all greenhouse gas emissions ceased immediately, oceans respond more slowly. As water warms it expands, occupying more space, while melting ice caps and glaciers further add to ocean volumes.

Sea level rises are not uniform, in part due to the unequal effect of tidal surges and also the unequal influence of our magnetosphere. Cairns, the Torres Strait and the Gold Coast are particularly vulnerable, but many sea front gardens all around Australia face a simple choice: adapt or decline. Even with a reduction in greenhouse emissions, an extra 23 million people could face coastal flooding. That includes Australians.

Some people seem willing to temporarily sandbag their homes to prevent the latest high tide from entering their property. This makes immediate sense, but there is a growing awareness about way this will affect the cost to insure property, the cost to repair infrastructure, and the impact on horticulture.

Others are looking to the future. So many things are already affected. Ten years ago I gave a lecture for the residents at Woodgate, QLD to discuss saltwater incursion, its impact on horticulture and which species to plant that can cope with saltwater incursion. Woodgate faces beach erosion, which has knock on effects on property land values and the cost of insurance. Residents were particularly concerned that saltwater is infiltrating freshwater aquifers used to irrigate crops in the Bundaberg region.

The CSIRO advises:

“Sea level changes impact on coastal ecosystems, water resources, and human settlements and activities. Regions at most risk include heavily populated deltaic regions, small islands (especially coral atolls), and sandy coasts backed by major coastal developments”.

You can read the CSIRO’s research about oceans and coasts, sea level rise observations, projections and causes.

Have a look at this ABC 7.30 Report (transcript and video) for insight into this issue, or read local coverage on yesterday’s king tide at the Courier Mail. While this information is useful, remember that the Greenland or Antarctic ice sheets are melting at stupendous rates that have alarmed the scientists studying them.

To secure the resale value of ‘Bellis‘, my home, I chose a place that is 1 km inland and over 10 metres above sea level at the time of purchase.

In March 2019, the United Nations warned the world has only 11 years left to prevent irreversible damage from climate change.

While true, the most sobering point is that should we cease all Greenhouse Gas emissions today, there is already sufficient in our atmosphere to guarantee a century or more of sea level rise. That’s a lot for our coastal gardens and ecosystems to absorb.

Jerry Coleby-Williams
Originally posted on 13th January 2009
Updated 15th December 2020