Summer 2009 - Scottish Natural Heritage

Living with change
Over the last hundred years, the average air temperature has
risen by about 0.7°C. But by the end of the present century,
the world could be as much as 4°C warmer than it is today.
This could start irreversible melting of the Greenland and
West Antarctic ice sheets over a period of a few thousand
years.
The geological record reveals how past environments
responded to broadly similar climate changes. The early to
middle Pliocene period (between three and fi ve million years
ago) gives perhaps the best idea of what a future, warmer
world might be like. Carbon dioxide levels in the atmosphere
then were around the same as they’ve reached today, and
global temperatures were about 3°C higher, with sea levels
up to 25 metres higher.
Some of the more far-reaching effects of climate change
are likely to be at the coast. The latest projections from the
Department for Environment, Food and Rural Affairs (Defra)
show a sea-level rise of 7 mm each year in Scotland in the
next few decades, outstripping rates seen in the last few
thousand years. The effects will probably be made worse
because natural coastal defences, such as beaches and
saltmarshes, won’t be topped up with new material, and
there are likely to be more frequent storms and fl ooding.
If we look at what’s happened to our weather over the
last 40 years, the future might hold the following:
– More frequent storms, especially in the west, leading to:
- more dynamic coasts and rivers that are challenging to
live near, especially in low-lying areas;
- fl ooding more often along rivers and at the coast; and
- greater disruption of transport routes, through landslides
and fl ooding.
– Carbon-rich soils become destabilised, leading to the
release of more greenhouse gases.
– Soil being eroded quicker, especially during windy or very
wet conditions.
– Changes in the depth and length of time that snow lies, as
well as more periods of high wind speed.
These changes will affect not only Scotland’s geodiversity
but also its plants and animals. For example, more fl ooding
and erosion will affect the quality of freshwater habitats
that are important for endangered species, such as the
freshwater pearl mussel and lamprey. Overall, species and
habitats may have less time to recover from extreme events,
such as fl ood damage to fi sh-spawning areas in rivers. Some
landform changes may simply be too fast for the species and
habitats they support to adapt or relocate.
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54 The Nature of Scotland