Net zero is the buzzword for 2021. This week’s Earth Day, a PR exercise at the best of times, is a case in point with another raft of companies pledging their roadmap to the elusive goal. Meanwhile, as the next global climate talks approach with COP26 in November, the UK as the host nation is under pressure to show green leadership.

The concept is to produce zero carbon emissions, by reducing your own as far as possible and then offsetting the remainder. But the practicality, in anything from calculating to regulating, is deeply flawed. As founder of organic veg box company Riverford, Guy Singh-Watson, put it recently: “If someone tells you that they will reach net zero, I urge you not to be impressed until they have told you how.”

The first obstacle is calculating emissions. The global Greenhouse Gas Protocol splits emissions into three ‘scopes’, or levels; a basic detail that’s missing from the vast majority of net zero pledges.

Scope one means the direct carbon emissions from a company (i.e. their own vehicles or generators). Scope two accounts for electricity usage. Scope three is everything else, which for a business that buys, sells and delivers goods, can cover anything from food waste to emissions from overseas factories.

“It's hard to hard to envision a responsibility for carbon that doesn't include all the orders that you're placing for raw materials and from factories. If you just hold businesses accountable for the things directly related to their corporate operations, you're missing 90 to 95 per cent of the impact,” explains Austin Whitman, chief executive of Climate Neutral, a US-based carbon neutral certifier that requires scope three emissions to be eligible for its scheme.

Once a company arrives at a carbon footprint figure and reduces that by as much as it possibly can, what it chooses to do next is just as complex. Offsetting is often linked to tree planting, which can be a problem for various reasons including the types of trees, the length of time they take to store carbon and the amount of land required.

But there are other natural habitats that also store carbon, alongside other ‘co-benefits’ like restoring nature and biodiversity, a crucial factor in tackling the parallel crisis in ecological and species declines.

Blue carbon

One of the single biggest carbon stores on earth is the ocean, and research is growing on the possibilities associated with so-called ‘blue carbon’ captured in marine ecosystems, such as the deep seabed, kelp forests, seagrass meadows, estuaries and the water itself.  

Cornwall-based charity Surfers against Sewage (SAS), which campaigns on the climate and ocean emergencies, is clear of the possibilities of storing carbon in the sea, alongside a major caveat about the risks of offsetting.

“Blue carbon is the most effective, yet overlooked, method for long-term carbon sequestration. For example, tidal marshes store carbon in the soil, several meters deep, at a speed two to four times greater than a mature tropical forest,” explains SAS campaigns officer, Elsa Pullman.

But she adds: “At SAS we believe that offsetting should only be used to offset the residual carbon emissions that cannot be prevented. Offsetting is often perceived as something organisations can do instead of cutting emissions. Whereas carbon sequestration is vital for tackling the climate crisis and should be seen as a nature-based solution to the climate crisis, not just an excuse to carry on emitting GHGs,” she adds.  

Seagrass

Seagrass is a marine flowering plant found in shallow, sheltered areas of the UK’s coastal waters, which stores carbon in its roots. As older plant tissue dies, this becomes trapped in the complex structure of a seagrass meadow before eventually making its way to the seabed where it can remain for thousands of years. As a result, seagrass meadows play a vital role in carbon storage, but the UK has lost 92 per cent of this unique habitat in the last century, according to conservation group Project Seagrass.

“This catastrophic loss has been attributed to poor water quality, historic mining activity, fishing activities and coastal development,” explains conservation officer, Bethan Thomas. And as well as its carbon storage potential, restoring these meadows has many other benefits.

“Through sequestering carbon, seagrass acts as a buffer against ocean acidification,” says Thomas. “Seagrass meadows in the UK are home to an estimated 50 species of fish and act as a nursery ground for juvenile fish, including commercially important species such as cod, pollack and whiting.”

The potential is impressive, and researchers at the universities of Swansea and Portsmouth are looking at how carbon accumulates in seagrass and to develop a valid calculation method. But Thomas echoes a similar stance to SAS and says: “We take the view that offsetting should be a last resort. Carbon offsetting schemes are useful while infrastructure transitions to low- or zero-carbon operations but they must not be used as a free pass for inaction and ultimately measures must first be taken to avoid or reduce emissions in the first place,” she says.

Wetlands

The UK’s tidal marshes and wetland areas offer another natural habitat where carbon can be stored alongside other valuable ecosystem benefits.

Carbon from the estuary or plants is buried after every tide, leaving behind a new layer of organic carbon-rich sediment that, thanks to the damp conditions, is stored rather than decomposing, says the Wildfowl and Wetland Trust (WWT), which is working with Manchester Met University on a project at Steart saltmarsh in Somerset.

The project found that the marsh stores 10,000 tonnes of carbon every year, with other benefits including reducing flood risk, providing space for nature and supporting biodiversity.

“There is potential to create wetlands such as saltmarsh to help meet carbon targets,” says a recent report, while head of policy and advocacy, Tom Fewins, adds: “Wetlands are critical blue infrastructure we can be putting in place now to reduce climate impacts and increase our resilience.”

Peatlands and hedges

According to a new report by Natural England this week, peatlands are the largest carbon stores in the UK and can continue to absorb carbon indefinitely if in healthy condition. Conversely, if they are disused, or used for agriculture, the release of carbon back into the atmosphere is extremely high meaning they become a source of emissions.

Hedges are also described in the report as “effective at storing significant amounts of carbon”, but tend to cover a smaller area and are cut regularly, limiting their impact.

Offsetting through restoring the above habitats may be an alternative to the vagaries of carbon trading or buying credits to fund projects in far-distant places. At the very least, there is merit in proximity to UK habitats that brings at least some transparency into the chain.

But there is still a challenge in how to calculate carbon for offsets, as Dr Daniel Lash, senior research fellow at the Centre for Energy and the Environment at the University of Exeter, points out: “They’re quite different things – water, peatlands, trees – and the data can be open to interpretation when you drill down into it.”

Lash says The Woodland Carbon Code is one of the most robust verifiers of carbon calculation, and while there is a move to get something similar for peat, the scheme currently only applies to trees. “You only really start thinking about offsetting when you literally can’t reduce any further,” he adds.

Electric infrastructure

For others, the sheer urgency of a climate changing even within this lifetime means any green investments raised by offsetting should be used for large-scale rollout of decarbonising infrastructure. “Something that we would like to see is a whole lot more acceptance of carbon finance as a way of decarbonising, in particular the energy sector,” says Whitman, of Climate Neutral.

While the wheels of dubious carbon finance are already in motion, Whitman remains positive about its impact. “Our view of offset is it's a proxy for a price on carbon that every company should be paying,” he says. “I think we have to think about this mechanism as a way of getting projects that will transform the global economy to happen, and not just planting a tree somewhere in Brazil.

“The reality is emissions are globally heading up two to three per cent per year and they need to be heading down eight per cent per year. And to make that happen we need to be investing in everything right now immediately.

“There's not enough land to plant enough trees. The investments that need to happen are much broader in electrical infrastructure,” explains Whitman, who says that after a career in finance, economics and environmental law and despite the flaws in the carbon sector, he can’t justify working on anything else.  

“I think people do a great job of identifying and acknowledging the scale of the problem but do a rotten job of identifying the bigness of the solution. To put it in pandemic terms – it’s like we've identified this global pandemic, but we're going to start treating it one village at a time. If your inoculation program is 100 people a day, of course you're never going to get control of it. The same is true of carbon.”

No easy answer

There is no easy answer to how companies, organisations or countries should, or can, achieve net zero. But there is some hope in how some of the biodiversity projects used on that journey could provide a real recovery for nature.

And for consumers looking to the brands they buy from to make a difference, the time is now for pressure, but also for questions.

So you’re aiming for net zero?

• Ask companies what scope of emissions they measure: one and two cover only direct emissions or electricity, whereas scope three accounts for everything that a company makes, buys, wastes, sells or ships.   
• Insist on reduction. Ask what they are doing to reduce emissions and by how much.
• Look carefully at offset projects on a case-by-case basis; who is verifying it, does it have any other positive (or negative) impacts on local people or biodiversity?