How can corporates looking to offset emissions ensure that the project they invest in will deliver? Technological advances may be part of the answer, says Catherine Early
No field of corporate climate action has attracted more controversy than offsets, with countless headlines associating the carbon credits with greenwashing. However, carbon sequestration in natural ecosystems is now endorsed by the Paris Agreement, the Intergovernmental Panel on Climate Change and certification schemes such as the Science-Based Targets Initiative in recognition of the difficulties some sectors have in removing carbon, and only after cutting or halting emissions wherever possible.
From June 2021–January 2022, offset prices increased more than threefold to around US$14.40, according to S&P Global Platts. Interest has grown alongside the proliferation of corporate net-zero emission pledges since COP26. But with corporates under pressure to hit targets and avoid greenwashing scandals, they want proof of what they have paid for.
“With the Clean Development Mechanism [the UN’s carbon offset programme], the focus was getting government money into the tropics to save the rainforest,” says Ed Milbank, owner of the UK’s largest private woodland at the Barningham Estate in County Durham and director of carbon measurement platform CSX Carbon. “When giving money philanthropically, businesses were happy as long as that work was done.” However, the numbers now have to add up. “When a corporate buys an offset for 1,000 tonnes of carbon, it wants hard evidence of that 1,000 tonnes, not an estimate towards it. But that level of detail isn’t available with current systems.”
Many corporates fear that a project they have invested in might turn out to be environmentally or socially damaging, he continues. “The corporate world is holding back from investing in nature-based solutions until there are projects that can give them the assurance that what they’re investing in is doing good.”
Tushita Ranchan, trustee of the Green Purposes Company, set up by the UK government to safeguard the purposes of the Green Investment Bank, agrees. “Most of the projects financed today are small. There are large amounts of money waiting to be invested, subject to the metrics and the outcomes being clearer. For example, what does ‘good’ look like if you invest in peatland restoration, and how can results be validated?”
Tree cover and carbon
It is hard to find evidence that a tree planting scheme has been successful. Though high quality satellite data can track deforestation, it has not typically worked well for tracking tree growth; trees can take 15 years or more to grow, and it is harder to see a tiny sapling growing in a field than a space where a tree once stood.
There is also the question of how much carbon each tree contains. The technique used by experts to calculate trees’ biomass content – and thus the carbon – is often rudimentary, involving measuring the tree’s diameter with a tape measure, estimating the height and using an equation dating from the 1960s. The result is an underestimate, since it calculates only the biomass of the trunk, not all the branches.
Technological developments could make tracking nature restoration easier and more accurate. The World Resources Institute (WRI) is developing techniques to measure both tree cover and tree carbon using higher resolution satellite data and light detection and ranging (LiDAR), a remote sensing method that uses light in the form of a pulsed laser to measure distances.
“The corporate world is holding back from nature-based solutions until projects can assure them that what they’re investing in is doing good”
Projects launched in November by the WRI’s Land and Carbon Lab are showing promise, says Katie Reytar, a research associate in the organisation’s forests programme. In one, the University of Maryland has developed a method to calculate both gains and losses in a forest – two sets of data that are typically considered separately. This shows net change in forest cover for the first time. Another dataset uses artificial intelligence and satellite data to detect tree cover outside forests, such as on farms.
Measuring carbon in trees is also an evolving field, says Nancy Harris, research manager at WRI’s Global Forest Watch. “Are the measurements that we’re taking from space on changes in height good enough to be able to predict changes in biomass? We can count the number of trees or estimate the amount of tree canopy in a given area from space, but we still need to correlate that with how much carbon is in that tree.”
CSX is working with scientists from Ghent and Oxford universities to solve this problem. Using terrestrial laser scanning (TLS) – which creates three-dimensional trees measurements – and geometric modelling, they can calculate the volume of a tree, and thus its biomass and carbon. The data is then matched with optical and LiDAR images acquired from drones. The idea is to build a database of tree carbon across all species and ages using TLS, and use it to make drone data more accurate, so that drones can eventually collect accurate assessments of any tree carbon. Researchers elsewhere in the world are also collecting data using this method.
“To inform a system such as the UK’s Woodland Carbon Code, you need to work very quickly and efficiently,” says Milbank. “If you’re relying on someone walking into a wood with a tape measure, it’s just not efficient.” Technology has two benefits over traditional methods, he adds – it improves accuracy, and is a cost-effective way to measure large areas.
Estimating peatland health
Other natural carbon sinks are also undergoing research. In Scotland, government nature conservation body NatureScot is using a technique developed with Terra Motion, a spinout company from the University of Nottingham, to monitor the success of peatland restoration. This uses satellite interferometric synthetic aperture radar (InSAR) to map bog surface movement. Healthy peatland is wet, with soft and spongy sphagnum mosses that swell and retain water, making it move. Drier peatlands are stiffer, and unresponsive to the addition of water. NatureScot can thus assess peatland condition and the effectiveness of the restoration techniques it is using in Peatland ACTION, a project to restore more than 25,000 hectares of degraded peatland.
Researchers hope the method could provide a better estimate of the amount, distribution, condition and associated carbon inventories of Scotland’s peatland, and a way to assess the impact of restoration. It could also identify areas at high risk of peat instability, fire and erosion, and show where urgent action might be needed. The researchers are growing more confident in terms of what the technique tells them about peatland condition, but are still investigating how it could be used as a reporting tool in terms of greenhouse gas uptake and re-establishment of vegetation, says Peatland ACTION’s Dr Henk Pieter Sterk.
However, there is already interest in using InSAR technology in this way from both within the UK and overseas, he continues. “InSAR was initially thought not to work as well on vegetated areas, but all those limitations have been removed and validated in the field. It’s showing us information that even a decade ago was deemed impossible.”
Unlocking investment
While these technologies do not answer all questions, such as whether an ecosystem improvement occurred due to a project or to other factors, they could provide the confidence needed to unlock larger-scale investment.
“The public interest in climate change and the importance of forests and trees has spurred action in a way that perhaps wouldn’t have happened before. Researchers have been working on these issues for decades, but there is now more funding and more focus on these areas, and more progress,” says Harris.
Catherine Early is a freelance journalist.
