Imagine you’ve been transported to the Antarctic Ice Sheet. What would you see? A vast, desolate desert of ice as far as the eye can see. No sign of life. No hint of change. An ancient environment so remote from civilisation you could almost be on another planet.
It would be hard to believe that the ice beneath your feet is accelerating towards the ocean. Harder still to believe that processes taking place here have consequences for Scotland’s future.
Changes in the Earth’s frozen regions and oceans are the subject of the latest report from the Intergovernmental Panel on Climate Change. The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate assessed the latest available scientific research and its findings are troubling.
Climate change, driven by human activity, is melting ice causing rising seas. Oceans are warming, having taken up more than 90% of the excess heat in the climate system since 1970. Absorption of carbon dioxide from the atmosphere has also led to acidification of the ocean.
These changes are causing more extreme weather events and increasing coastal hazards. They are also having an impact on high mountain, marine and polar ecosystems.
Human impacts include food security, water resources, water quality, livelihoods, health and well-being, infrastructure, transportation, tourism and recreation, as well as culture of human societies, particularly for Indigenous peoples in the Arctic.
But how are these changes impacting Scotland and what might be the impact by the end of the century?
The importance of Scotland’s coastal and marine environment
According to the James Hutton Institute, nearly half of Scotland’s population lives within 5 km of the coast. 33% of Scotland’s agricultural land lies within the 5 km coastal area.
Scotland’s seas also contain over 40,000 species and 60% of Scotland’s food exports come from our seas, worth £917 million in 2018.
Protecting coastal and marine assets from the impacts of climate change is therefore crucial to securing the future of Scotland’s economy, society and natural environment.
Rising seas
Rising temperatures are causing the Earth’s glaciers and ice sheets to melt. When meltwater from land-based ice enters the oceans, sea-levels rise. Warming also causes the oceans to expand, raising sea-level further.
The global average rate of sea-level rise is currently estimated at 3-4 mm per year and the report estimates an average global sea-level rise of between 24-32 cm by the end of the century.
Taken at face value, this doesn’t sound like a lot. But a small rise in sea-level has the potential to increase coastal hazards such as flooding, coastal erosion and loss of coastal land leading to displacement of people. The IPCC report says:
“Extreme sea level events that are historically rare (once per century in the recent past) are projected to occur frequently (at least once per year) at many locations by 2050 in all RCP scenarios…”
In the UK, predicted sea-level rise is lower in Scotland compared to southern England. This is because the land is still rebounding from the immense weight of the ice sheet once centred over Scotland.
However, this rise in the land is slowing and is no longer outpacing the rate of sea-level rise. The Scottish Government estimates that £400 million of coastal assets will be threatened by 2050.
Predicted rates of change over the next century also vary regionally due to differences in the rate of land movement and the effect the Earth’s gravitational field has on water levels. The chart below shows projections of future sea-levels around Scotland based on low, medium and high emissions scenarios.
The damage caused by rising seas also depends on the height of the land and the ability of communities to build flood defences. For example, low lying regions such as South Uist in the Outer Hebrides could stand to lose large areas of land over the next century.
The potential impact for these islands was recently raised in a parliamentary question by Alasdair Allan MSP and was the subject of an art installation showing a future sea level projected across the landscape.
Fisheries and the marine environment
Warming oceans also creates pressure on fish stocks and the wider marine ecosystem. The marine environment is being damaged by warming, acidification, loss of oxygen and changes in nutrient supplies.
On marine animals, the report says:
“A decrease in global biomass of marine animal communities, their production, and fisheries catch potential, and a shift in species composition are projected over the 21st century in ocean ecosystems from the surface to the deep seafloor under all emission scenarios”
There were also troubling predictions for ecosystems supporting fish and other marine wildlife:
“For sensitive ecosystems such as seagrass meadows and kelp forests, high risks are projected if global warming exceeds 2°C above pre-industrial temperature, combined with other climate-related hazards (high confidence).”
The effect of climate change isn’t just a future concern. News emerged this week that North Sea Cod has lost its Marine Stewardship Council sustainability certification after stocks fell below sustainable levels. Scientists have indicated warming waters caused by climate change as one of the factors affecting populations.
What can be done?
Sea-level rise is projected to continue beyond 2100 in all emissions scenarios. Even if urgent action is taken to curb emissions, there will be unavoidable impacts of sea-level rise and the wider impacts on marine ecosystems from greenhouse gases already emitted. On solutions, the IPCC report says:
“Coastal communities face challenging choices in crafting context-specific and integrated responses to sea level rise that balance costs, benefits and trade-offs of available options and that can be adjusted over time (high confidence). All types of options, including protection, accommodation, ecosystem-based adaptation, coastal advance and retreat, wherever possible, can play important roles in such integrated responses (high confidence).”
In September this year, the Scottish Government published Climate Ready Scotland: Second Scottish Climate Change Adaptation Programme 2019-2024. It contains seven outcomes setting out current policies, proposals and research to increase the capacity to adapt to a changing climate. Outcome 6 is focussed on the coastal and marine environment:
“Outcome 6: Our coastal and marine environment is valued, enjoyed, protected and enhanced and has increased resilience to climate change.”
From 2015-2020, the Scottish Government has funded the Dynamic Coast research project to build an evidence base to plan resilience to future coastal change. This research considers multiple research questions including: the extent and resilience of natural coastal flood protection features; climate change accelerations; technological improvements and the development of adaptation and resilience plans.
Mitigating the impacts of sea-level rise and changing ocean conditions will require continued scientific monitoring and long-term planning.
Damon Davies, Researcher, Brexit, Environment and Rural Affairs