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The science behind our carbon offsetting

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Bluebells in the sun

Jenny Connell has worked in the Environment Agency for 15 years. She is a Senior Specialist in the Environment Agency’s net zero team – and here, she gives an insight into the science behind the EA’s carbon offsetting strategy to mark International Day of Women and Girls in Science.

I wouldn’t say that science was an immediate hit with me.

But from an early age I read a lot of books, and I loved popular science books – I still do. There is a real skill in making science accessible for people and translating the concepts into real life.  I also had an early interest in environmental issues, and I suspect some of my high school teachers predicted my future career direction long before I did – one of them used to joke about me running my (very old) car on elderberry juice.

I studied Environmental Science at university and after I graduated I was keen to work in an environmental field. My first job was actually a year-long placement at a steel works – I did water and air quality monitoring. It was physically hard work at times, but really interesting and a very real world experience. It was a great starting point to seeing some of the practical applications of science.   I started my career at the EA working on delivering our flood risk capital programme, making sure projects are designed and delivered in the most environmentally sustainable way.  Sustainability covers a broad range of issues, and having a good understanding of the various scientific principles that underpin them has been a really useful skill over the years.

I’m currently working on our organisational carbon offsetting strategy, which supports our net zero ambitions by setting out how we plan to abate our unavoidable residual emissions.

Just to clarify, offsetting is a valuable tool in responding to the climate emergency – but it should never be used as an alternative to emissions reductions. “Here in the EA, we have committed to cutting our emissions first, and then offsetting the rest through projects that harmlessly lock away carbon while bringing added benefits for people and nature.”

We are pursuing a nature-based approach to carbon offsetting.  This means we’ll use habitats like woodland or saltmarsh to lock away carbon dioxide.  These habitats also have additional environmental and social benefits, such as reducing flood risk, improving water quality and providing valuable recreation spaces for local communities. A win for everyone!

In 2021 we carried out and published work led by Dr Lydia Burgess-Gamble that explored the evidence for various habitat types and their carbon sequestration potential. It concluded that nature-based solutions could play an important role in offsetting, but that the scientific understanding of how effective different habitats are is variable.

Our offsetting strategy is building on this valuable work to better understand the contribution that different habitat types can make to offsetting our residual emissions. We’re doing this by modelling a range of offsetting scenarios using a carbon sequestration model.  We will use this work to make evidence-based decisions and inform our final approach to offsetting.

In parallel with this, we are also developing a carbon protocol to set out how we calculate, record and monitor our carbon sequestration.  It’s really important that this approach is grounded in science, because we need to be sure that any sequestration we claim has actually occurred, and that it can be evidenced.  The scientific understanding of how much carbon habitats can absorb is evolving all the time, so we expect our protocol to evolve too.  This work is in early development but the range of scientific disciplines that need to be involved in it is huge – from carbon and habitats specialists through to experts in remote sensing and satellite monitoring.  As the person bringing this all together I’m really enjoying the opportunity to learn about new evidence and technologies. For me that is what science is about - having an open mind, being willing to learn new skills and solving problems.

It’s really important that we involve everyone in how we respond to the climate emergency - this is the biggest challenge we have ever faced and we need diversity in our thinking to tackle it effectively.

I feel lucky to have the opportunity to work in a roll that is helping to fight climate change. It feels really positive to be working on a project that has the potential to deliver huge benefits to the climate, people and nature.

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  1. Comment by b.morris posted on

    Along with the burning of fossil fuels - or, indeed, any fuels - land use is acknowledged as a major cause of climate warming. This is largely because most ways in which humans use land involves the disruption of soil and soil processes: and this leads, first, to the release of carbon into the atmosphere and, second, to reduction of the carbon-storing capacity of the soil from that point on.

    As climate warming increases, the need to extract carbon from the atmosphere increases also. While there is a general understanding that trees (and plants of all kinds) extract carbon from the air and store it in their leaves, roots, branches and trunks, it is less often acknowledged that this is only the first part of the two-part process of long-term natural carbon storage. The real carbon store is not the trees and plants, but the soil beneath and around them. Trees and plants are the conduit for carbon moving out of the atmosphere and into the soil.

    When it falls, every leaf, needle, flower, seed case, twig, branch and trunk of any tree and plant will carry its stored carbon to the ground and there - if left in peace - it will be decomposed by the flora and fauna on the surface of the soil and within it . The carbon will gradually be incorporated into the structure of the soil (including within soil organisms which make up a proportion of healthy soils). Unless the soil is disturbed at a later date, the carbon will, one way or another, remain there supporting a rich diversity of soil organisms and soil processes which in turn will support plentiful plant growth above ground. In the case of leaves and twigs, decomposition into the soil can be a fairly speedy process. Branches and trunks may take some years longer - gradually decomposing while providing habitats and food sources for insects and small animals which are themselves part of the same carbon-sequestration process.

    So when it comes to a nature-based approach to carbon-sequestration, there is no need to limit it to habitats such as saltmarsh and woodland. The principles of carbon-sequestration through soil-formation can be applied to any kind of land-use – agriculture, forestry, small woodlands, roadside verges, parks, open spaces around large buildings, green areas around blocks of flats, and even individual gardens.

    For instance, agriculture methods can be adjusted so that their by-products leave higher levels of soil-forming organic material on the ground year on year: thus deepening the soil over time, improving its structure, enriching its nutrient levels, supporting a richer flora and fauna, and of course increasing its carbon content for the long-term. Forestry can be encouraged to leave on the ground any parts of felled trees which cannot be used to make long-term carbon-sequestrating items such as building materials and furniture. With roadside verges, parks and open spaces, grass mowing machinery can finely chop the arisings from each mow and allow it to fall back on to the grassland. Owners of green space around buildings and houses can be encouraged to adapt their grounds maintenance in ways which support soil building in situ: while engineers and architects can be encouraged to design larger green areas within new developments, retaining the original soil on site.

    As well as removing carbon from the air, increasing the organic content of soil has other benefits at a time of climate warming: it supports the retention of moisture in the soil, which cools the air during hot, dry spells - to the benefit of humans, animals and plants. In a natural state, soil builds and deepens over time, through the natural decomposition of plants and animals and the weathering of the underlying rock: soil is never just a one-off deposit but always a complex of materials, processes, weather, and time. A soil which increases in depth year on year through the decomposition of organic matter is a soil which can maintain future plant growth at today's levels (rather than thinning out in years to come as climate change brings longer periods of hotter, dryer weather). Further, maintaining tree growth over a wide area can potentially help stabilise the local weather patterns that bring rain, further mitigating to some extent the future impacts of climate change

  2. Comment by Administrasi Bisnis posted on

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