Recent research from Sweden shows that lakes in the near-Arctic are emitting as much carbon dioxide (CO2) as those in warmer regions. This finding means that globally, lakes emit a quarter of the total CO2 released by burning fossil fuels and are considered to compensate for the uptake of CO2 by the world’s oceans.
What does this mean for water? The scientific community has known for some time that lakes can emit carbon dioxide through respiration, and that lakes have a disproportionately large role to play in the carbon cycle, relative to their size. The Swedish study found that most of the CO2 emitted by thousands of small near-Arctic lakes comes from agricultural sources where the land use are such that the surrounding catchments are not providing a natural buffer to absorb excess nutrients.
This research highlights the importance of preserving our ecosystems and the land that surrounds them. Furthermore, the study points to the importance of increasing our understanding of fresh waters role in climate change prediction models.
The study also shows that CO2 is emitted from these lakes as they become warmer and richer in nutrients. The planet has just surpassed the 1 degree global temperature increase, and if we are unable to prevent further rises we may see a further rise in CO2 emissions from millions of lakes, a process called positive feedback.
A further effect of climate change is the increase in flooding incidents, and it has been shown that lakes can become great greenhouse gas emitters in the years following a flood – thus the positive feedback cycle is perpetuated.
As world leaders at the Paris Climate Conference aim to achieve legally binding agreements on tackling climate change and following the announcement that the UK will cease burning coal in power stations in the next decade, what else can we do to reduce the impact of waterbody CO2 emissions?
FreshWater Watch citizen scientists observe water colour as well as turbidity (cloudiness), both of which can be indicators of the carbon emissions of micro-organisms in the waterbody. Lakes and rivers that are coloured “brown” are usually rich in organic matter which is converted into CO2 and methane (CH4) by microbial activity and photodegradation (by the sun). Lakes and rivers that are coloured “green” are usually producing large quantities of algae, absorbing CO2.
22% of FreshWater Watch measurements have observed brown coloured water. 18% of samples have observed green water or algal blooms.
Earthwatch’s scientists work on many projects as well as FreshWater Watch. Earthwatch scientist Dr Alan Jones has studied carbon cycling extensively. He has found that climate change causes more dissolved carbon to be released from Arctic soils, which supports the findings of the new Swedish paper, showing that both land use change and Arctic warming combine to accelerate climate change. Therefore, to protect ourselves from climate change, we need to preserve ecosystems that are already intact.
Citizen scientists can take part in research; join FreshWater Watch, the largest fresh water study in the world! Alternatively you could join Earthwatch on dry land by studying carbon cycling in UK woodlands.
To find out more on the research and Paris Climate Conference check out this blog from CDP, the Carbon Disclosure Project, on why water shouldn't be forgotten at the Paris Climate Conference.