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The Impact Of Drought On Biodiversity

This year saw some record-breaking temperatures hit around the country, with prolonged periods of dry weather and several heatwaves during the summer… which have converged to put even more pressure on water resources all over the UK.

Maximum temperatures this summer were far above average for much of England in 2022, with a new record temperature set for the UK at 40.3 degrees C, recorded in Coningsby in Lincolnshire back in July. Both July and August saw very little rain, with the summer as a whole registered as the fifth driest since records began in 1836.

By the end of summer, the lack of rainfall coupled with a rise in water demand in line with all the hot weather saw reservoir stocks in the south of England dip exceptionally low.

In fact, figures from the UK Centre for Ecology & Hydrology (UKCEH) show that reservoir stocks for England and Wales at the end of August were the second lowest since records were started in 1990.

The entirety of the south-west region of England is now in drought status and it seems that this situation is likely to persist, despite the wet weather that has been seen since the start of September.

Although the wetter conditions have seen river flows increase, monthly river flows are still low and the majority of sites in England and Wales are still below normal.

And the outlook for the rest of the year indicates that total rainfall is unlikely to be above average and, as the UKCEH explains, there is little to suggest right now that we’ll see the prolonged wet weather we need to reverse the drought situation.

What will this mean for biodiversity around the UK?

Dry conditions and drought are expected to remain as they are for the next couple of months at least, with some experts going so far as to suggest that drought will persist until summer 2023.

Drought can have a serious impact on rivers, lakes and streams, affecting the water quality and putting wildlife and plants at serious risk. The more prolonged the drought conditions, the worse the potential impacts are likely to be.

For example, the UK’s oldest trout farm in Bibury in the Cotswolds has just suffered the loss of up to 25,000 fish because of a lack of rainfall and drought. Springs that typically supply the farm have now dried up, producing nothing since the summer months.

In previous years, they would produce 200 litres of water every second, but now the trout farm is reliant upon Thames Water to top water levels up from a local pumping station, ITV reports.

As drought conditions persist, the nation’s freshwater environment will be affected more and more, with water levels dropping in aquifers, wetlands, lakes, rivers and chalk streams.

As these waterways dry up over time, they start to fragment and break up the connectivity of our streams and rivers, while reducing the available habitat for wildlife at the same time. Prolonged drought also means that natural flooding can be affected, events that can prompt migration and spawning. Without these, animal lifecycles can be affected in the future.

Habitats are also put at risk during persistent drought conditions, with a reduction in shading and cooling effects putting ecosystems in danger, thanks to fewer trees, shrubs and so on. This, in turn, can have a big impact on fish and plant populations.

What about water quality?

One of the biggest problems facing the UK’s waterways is the amount of pollution that enters our rivers, lakes and streams on a regular basis. Agricultural runoff and sewage discharges are having a big impact on water quality around the country, but drought can exacerbate the situation, potentially quite significantly.

Dry conditions mean that water levels decrease. Wastewater pollutants include nitrates, phosphates and other chemicals that are already damaging to water quality, but when river flows are low, these chemicals and pollutants become more concentrated and have the potential to cause even more damage than before.

Algal blooms are already common, the result of increased levels of nutrients (particularly some phosphates) in the water that makes it look green, blue-green or even greenish-brown.

Some types of algae can produce toxins that can kill wildlife and livestock, as well as causing harm to people by producing rashes if come into contact with or illnesses if ingested. These blooms also block out the sunlight, preventing it from reaching other aquatic plants, as well as using up the oxygen in the water, putting fish and other animals at risk of suffocation.

More frequent and more extreme periods of drought may well increase the abundance of these algal blooms because there isn’t enough rainfall to clear them from waterways. It’s also possible that higher climate change-associated temperatures may actually help drive the growth of these blooms, causing even more problems for local biodiversity.

Scientists have now said that the climate crisis made this year’s record drought that hit the northern hemisphere so hard at least 20 times more likely – and events such as this would only have been expected once every 400 years, without human-related global heating.

Professor Sonia Seneviratne at ETH Zurich, member of the analysis team, was quoted by the Guardian as saying: “The 2022 summer has shown how human-induced climate change is increasing the risks of droughts in densely populated and cultivated regions. We need to phase out the burning of fossil fuels if we want to [prevent] more frequent and more intense droughts.”

With COP27 just around the corner, a new International Drought Resilience Alliance is set to be launched at the conference in Egypt, in recognition of the fact that drought management approaches must be shifted from emergency response to building resilience.

The latest Drought in Numbers report from the UN Convention to Combat Desertification has just revealed that droughts have increased in frequency by 29 per cent since 2000… and no country is immune to the problem. The time to act, it seems, is now.

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