How might rising sea levels affect the Isles of Scilly?


Introduction

Rising sea levels are a widely-known consequence of the climate crisis and the potential impact is often demonstrated by showing famous and populous places, such as London or Amsterdam, having areas underwater due to different levels of sea rises. I wanted to take this idea and apply it to a lesser-known place which will likely experience very damaging effects due to rising seas: the Isles of Scilly.

The archipelago off the south west coast of Cornwall is somewhat of a hidden gem; there are beautiful beaches and a quaint atmosphere, and the with highest average temperature of anywhere in the UK, there is an abundance of flowers and succulents which are hard to find elsewhere in the country. However, much of this may be at risk if sea levels rise at rates predicted by some scientific models. In the following maps I have shown an estimate of how the island group might be affected by different levels of rising.

This project was completed in QGIS.


0m rise (current)


1m rise


2m rise


3m rise


4m rise


5m rise



Methodology

All of the data for this project is from the OS data hub - specifically the Boundary Line files for the isle boundaries, and the OS Terrain 50 for the altitude.

I first added a vector layer of GB council boundaries, and then clipped it be just the Isles of Scilly using the query builder.

For the altitudes, I first used contours but decided that a coloured height map would be more meaningful. I downloaded the ASCII grid raster layers and added the four relevant files into the project. I merged these layers then created a custom colour ramp and applied it to the layer to show the altitudes from dark green to dark purple, with the sea as blue. As the data takes into account both low and high tide, 0m did not exactly align with the boundaries of the islands, so I used -1.5m as the current sea level instead, which seemed to correspond to the vector shapes the best.

For each level of sea rise, I then bumped up the scale by 1m each time, apart from the sea level which jumped straight from -1.5m to 1m at first.