This article starts with an overview of climate change globally and then moves (see section 5 onwards) into a description of its likely impacts in Devon. It includes videos of presentations by two experts on climate change impacts, given at our Discover the Culm event in October 2020.
1. Overview of climate change
Over the last 150 years or so the average temperature of the planet has risen by around 1°C. This is a rapid change in our global climate system, which has been stable for the last 11,000 years. Over this same time the amount of carbon dioxide, methane and several other gases in our atmosphere has increased dramatically. These gases are known as greenhouse gases because they slow the escape of heat from the planet’s surface into space. Without these gases present in small quantities, the earth would be bitterly cold and life would not be possible for humans; but when their concentrations get too high, too much of the sun’s energy is trapped, temperatures rise and a series of changes are triggered, including melting ice sheets, rising sea levels and the loss or migration of species: this is the process known as climate change.
2. Where do greenhouse gases come from?
Natural processes like plant and plankton growth and animal digestion generate greenhouse gases but the rapid increase in the atmosphere in the last two centuries is due mainly to human beings burning fossil fuels, farming and land use changes, deforestation, and the manufacture of cement, chemicals and metals.
Professor Richard Betts MBE, Fellow and Head of Climate Impacts Research, The Met Office talks about climate impacts globally and locally
3. Climate change impacts globally
The effects of climate change are already being felt across the planet, in some places more than others, but nowhere has remained unchanged.
Changes to the climate system include:
Extreme weather events – Climate change is causing many extreme weather events to become more intense and frequent, such as heatwaves, droughts, and floods.
- Rising ocean levels – Rising temperatures are causing glaciers and ice sheets to melt, adding more water to the oceans and causing the ocean level to rise. Oceans absorb 90% of the extra heat from global warming: warmer water expands, and so our oceans are taking up more space.
- Ocean acidification – Ocean acidification occurs when the ocean absorbs carbon dioxide and becomes more acidic. It is often called the ‘evil twin’ of climate change and damages coral reefs and other essential marine ecosystems.
These changes can also affect people and ecosystems in other ways. For example:
- Flooding of coastal regions – Coastal cities are at risk from flooding as sea levels continue to rise.
- Food insecurity – High temperatures, extreme weather events, flooding, and droughts can damage farmland and make conditions difficult and uncertain for farmers to grow crops.
- Conflict and climate migrants – Climate change is a stress multiplier – it can take existing problems, such as lack of food or shelter, and make them worse. This can result in conflict over resources (food, water, and shelter), or cause people to migrate.
4. What does the future hold?
Climate models can range from a very simple set of mathematical equations (which could be solved using pen and paper) to the very complex, sophisticated models run on supercomputers (such as those at the Met Office). While these models cannot provide very specific forecasts of what the weather will be like on a Tuesday in 100 years’ time, they can forecast the big changes in global climate which we could expect to see in the future.
All these climate models tell us that under a scenario of ever-increasing greenhouse gas emissions the world could become up to 4.8°C warmer than the pre-industrial period by the end of this century. Note these are global averages and that temperatures in certain regions, such as the Arctic, would be even higher than this.
In the Paris Agreement of 2015, the nations of the world agreed to try to limit global temperature rise this century to “well below” 2°C and ideally below 1.5°C. The Climate Action Tracker is a useful tool for visualising where the world stands in relation to the Paris Agreement with current climate change mitigation commitments, looking at policies and modelling at the global scale.
To achieve the target of the Paris Agreement (when we have already triggered warming of 1°C), is going to be a huge challenge for almost every part of society on the planet. It is an important challenge too. We know that if warming of 4°C happens, the impacts on us and the rest of life on the planet will be dangerously high. We can seek to adapt to warming below 2°C, but above this level it will become increasingly hard for normal life to continue.
This is why we need to focus partly on adaptation (becoming more resilient to the changes that we know are happening already and in the near future) and partly on mitigation (rapidly reducing our greenhouse gas emissions) to try and reduce the risk of warming over 2°C.
Connecting the Culm is first and foremost an adaptation project. But, as we look ahead with our Blueprint for the Culm, we are also planning to incorporate carbon emission reduction plans that can simultaneously help make us more resilient. Tree planting is a good example: the trees slow flood water and help soils absorb more water, but they also lock in carbon from the atmosphere.
Jo Neville of the Westcountry Rivers Trust, author of a report on the impacts of climate change on Devon’s environment.
5. Climate change impacts in Devon
As a result of climate change, Devon’s weather is certainly changing, and we are already seeing both wetter and warmer winters, and more frequent hot and dry periods increasing the risk of drought in summer, plus more frequent extreme weather events such as storms with more intense rainfall causing floods.
The data shows that South West England is experiencing almost 10% more rainfall over the year now than it did in 1961. Seasonal rainfall is highly variable, but since 1961 it has decreased by 9% in summer and increased in autumn by 28% and in winter by 16%.
Our winters are also milder – on average per year, South West England has almost 21 fewer days of air frost than it did in 1961.
With the current rate of global greenhouse gas emissions, the most likely estimates are that by the 2080s:
- mean summer temperatures in Devon will increase by between 2.4 and 8.3°C (with the warmest summer day being up to 9.4°C hotter than the 1961 – 1990 average)
- precipitation will increase by 20 –50% in the winter and decrease by 30 –40% in the summer.
Can we predict what climate change is likely to mean for our environment, communities and economy here along the River Culm if we don’t take action now to tackle the problem? This is a complex area when working across a relatively small landscape but a 2019 research project covering the East Devon area assessed a wide range of factors. It assumed a worst-case scenario for climate change, where the global average temperature increases by up to 4.8°C by the end of this century (this is what we are on course for if we don’t cut back on our greenhouse gas emissions).
The report particularly focused on the impact of flooding and found that in a maximum flood event in the year 2100 up to 193 km of roads, including 2km of motorway and 13km of A-roads would be inundated. 19km of railway would also be affected including the main regional railway connection, which together with the motorway flooding would disconnect Exeter and the southwest from the rest of the UK. Up to 45 square kilometres of cropland would also be flooded, affecting food supplies.
The report also found that farming will be strongly affected by these changes to our climate and the increasing risk of flooding and drought. Although some new crops that are better adapted to drier and hotter summers, like grapes, sunflowers and olives, could become viable, parts of South West England are likely to become non-viable for some current farming activity, like growing potatoes, because of their need for water during the summer. Increased winter rainfall could lead to an increase in soil compaction and erosion from heavy machinery and bare ground being left exposed.
Natural Devon’s State of the Environment report (2018) estimates that the economic damage caused by flooding in Devon will rise from £81m/year now to £1billion/year by 2100.
6. What does this mean for you?
The Connecting the Culm project aims to help protect our communities and our natural environment from the impacts of climate change, and in particular flooding and drought. By working together, and by working with nature, we can build a river catchment that is better able to withstand extreme weather events, and at the same time create better places for nature and people.
We aim to explore the latest data and assess what the impacts will be on the people and environment in the Culm catchment as closely as possible. Some data has only recently been made publicly available by the Met Office at a small enough scale that we can map predictions accurately onto the Culm
This article has identified some of the ways in which the climate is already changing and will continue to change, and some of the impacts this will cause. Through the Connecting the Culm project we want to explore what these changes will mean for people, their properties and livelihoods, and the natural environment. Additionally, we want to build a plan together so we can manage these changes carefully, making sure that people and nature are protected in the best way possible. This is where we would like your involvement if you are a local person: to help create our Blueprint for the Culm that will mean we have a shared understanding of the challenges we face, and act collectively to adapt to them.
There are many different organisations at local, regional, national and international levels also working to help adapt to climate change. A good place to stay connected and to find out more is via updates from Connecting the Culm and the Devon Climate Emergency newsletter.
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