The Water and Carbon cycles are linked in many ways with one example being the way that carbon dioxide dissolves in water. Global warming increases evaporation and as a result the amount of water vapour in the atmosphere also increases. Water vapour is a greenhouse gas and this increases temperature further, in a negative feedback loop, increasing temperatures and precipitation. Water vapour is also a source of energy within the atmosphere and this increased energy results in more extreme weather events.
Human activities such as population growth, urbanisation and industrialisation have altered the size of water and carbon stores and rates of transfers between stores. Changes in the Carbon cycle can have significant impacts on climate at local and regional scales, not only in tropical rainforests, but also closer to home, in Borrowdale, England’s wettest valley.
Seathwaite, in Cumbria, is England’s wettest inhabited place and receives on average 3330 mm of rainfall a year. In June 2023 the area entered a state of drought for the third consecutive summer.
The photographs below show the same stretch of the Upper River Derwent, one taken in January 2023 and the other taken in June 2023. It is clear to see that the river is drying up and this will have significant impacts on the ecosystems in the area. Rivers are directly affected by global warming because warmer water carries less oxygen and, in addition, when river levels drop, the concentration of any pollution present will increase. The area is home to wildlife that is so important that the area has been designated a Site of Special Scientific Interest (SSSI) and it includes otters, salmon (who struggle when water temperatures approach 22-24 degrees celsius) as well as a rare fish called a vendace.
Photos: River Derwent flood conditions to drought conditions from Grange, Borrowdale
Management strategies are essential to manage the global water and carbon cycles. Key players in this area such as West Cumbria’s River Trust and the National Trust are working hard on River Restoration, afforestation and restoration of peat bogs to mitigate the impacts of the changing climate. See www.westcumbriariverstrust.org/projects/river-restoration-strategy and www.nationaltrust.org.uk/visit/lake-district/borrowdale-and-derwent-water/derwent-riverlands-behind-the-scenes for more information on the strategies being used.
As well as mitigation strategies, in the short-term adaptation strategies have been implemented. Another key player, the Environment Agency, has relocated over 1000 fish from a nearby tributary of the river Derwent after the hot weather caused low water and an increase in algae.
In winter, it’s a different story, with the area experiencing frequent floods. Areas like this need to become more resilient, reducing vulnerability and improving capacity to cope with the impacts of both human and physical factors that have changed both the carbon and water cycles at global and local levels.
Example exam questions related to this area of study:
AQA - Assess the extent to which there are interrelationships between processes in the water cycle and factors driving change in the carbon cycle (20)
Edexcel - Using examples, assess the extent to which deficits in the hydrological cycle can have significant impacts (12)
OCR – The damaging impact of human activities on the carbon cycle is of greater significance than on the water cycle. Discuss. (16)
OCR – Examine how rising levels of global CO2 in the atmosphere can affect people, economy and society in landscape systems (8)
WJEC – Examine the impacts of recent changes in the atmospheric carbon store on the water cycle (18)