̽��ֱ�� of Cambridge - Tom Swinfield

Offset markets: new approach could help save tropical forests by restoring faith in carbon credits

jg533 — Mon, 30 Oct 2023 16:15:05 +0000

A new approach to valuing the carbon storage potential of natural habitats aims to help restore faith in offset schemes, by enabling investors to directly compare carbon credit pricing across a wide range of projects.

Current valuation methods for forest conservation projects have come under heavy scrutiny, leading to a crisis of confidence in carbon markets. This is hampering efforts to offset unavoidable carbon footprints, mitigate climate change, and scale up urgently needed investment in tropical forest conservation.

Measuring the value of carbon storage is not easy. Recent research revealed that as little as 6% of carbon credits from voluntary REDD+ schemes result in preserved forests. And the length of time these forests are preserved is critical to the climate benefits achieved.

Now, a team led by scientists at the ̽��ֱ�� of Cambridge has invented a more reliable and transparent way of estimating the benefit of carbon stored because of forest conservation.

̽��ֱ��method is published today in the journal Nature Climate Change. In it, the researchers argue that saving tropical forests is not only vital for biodiversity, but also a much less expensive way of balancing emissions than most of the current carbon capture and storage technologies.

̽��ֱ��new approach works a bit like a lease agreement: carbon credits are issued to tropical forest projects that store carbon for a predicted amount of time. ̽��ֱ��valuation is front-loaded, because more trees protected now means less carbon released to the atmosphere straight away.

̽��ֱ��technique involves deliberately pessimistic predictions of when stored carbon might be released, so that the number of credits issued is conservative. But because forests can now be monitored by remote sensing, if projects do better than predicted – which they usually will – they can be rewarded through the issue of further credits.

̽��ֱ��payments encourage local people to protect forests: the carbon finance they receive can help provide alternative livelihoods that don’t involve cutting down trees.

And by allowing for future payments, the new method generates incentives for safeguarding forests long after credits have been issued. This contrasts with the current approach, which passes on a burden for conservation to future generations without compensation for lost livelihoods.

̽��ֱ��approach also allows different types of conservation projects to be compared in a like-for-like manner.

“Until now there hasn’t been a satisfactory way of directly comparing technological solutions with nature-based solutions for carbon capture. This has caused a lack of enthusiasm for investing in carbon credits linked to tropical forest protection,” said Dr Tom Swinfield, a researcher in the ̽��ֱ�� of Cambridge’s Department of Zoology and senior author of the study.

He added: “Tropical forests are being cleared so quickly that if we don’t protect them now, we’re not going to make the vital progress we need towards net-zero. Buying carbon credits linked to their protection is one of the best ways to do this.”

Tropical forests play a key role in taking carbon dioxide out of the atmosphere, helping to reduce global warming and avert climate catastrophe. But the carbon they capture is not taken out of the atmosphere permanently: forests can be destroyed by pests, floods, fire, wind – and by human clearance.

This impermanence, and therefore the difficulty of reliably measuring the long-term climate benefit of tropical forest protection, has made it an unattractive proposition for investors wanting to offset their carbon emissions.

And this is despite it being a far cheaper investment than more permanent, technology-based methods of carbon capture and storage.

Protection of tropical forests, a nature-based solution to climate change, comes with additional benefits: helping to conserve biodiversity, and supporting the livelihoods of people living near the forests.

“Nature-based carbon solutions are highly undervalued right now because the market doesn’t know how to account for the fact that forests aren’t a permanent carbon storage solution. Our method takes away a lot of the uncertainties,” said Anil Madhavapeddy, a Professor in the ̽��ֱ�� of Cambridge’s Department of Computer Science and Technology, who was involved in the study.

̽��ֱ��new method, developed by scientists at the Universities of Cambridge and Exeter and the London School of Economics, is called ‘Permanent Additional Carbon Tonne' (PACT) accounting, and can be used to value a wide range of nature-based solutions.

“Carbon finance is a way for us – the carbon emitters of the richer world – to direct funds towards rural communities in the tropics so they can get more out of the land they have, without cutting down more trees,” said Andrew Balmford, Professor of Conservation Science at the ̽��ֱ�� of Cambridge and first author of the paper.

Co-author Srinivasan Keshav, Robert Sansom Professor of Computer Science at Cambridge added: “Our new approach has the potential to address market concerns around nature-based solutions to carbon offsetting, and lead to desperately needed investment.”

Conversion of tropical forest to agricultural land results in vast carbon emissions. Around 30% of all progress towards the ambitious net-zero commitments made at COP26 is reliant on better management of carbon in nature.

Other carbon credit investment options include technologies that remove carbon dioxide from the atmosphere and lock it deep in the Earth for hundreds of years. These permanent storage options may currently be easier to value, say the researchers, but they typically cost substantially more than nature-based solutions and do nothing to protect natural habitats that are vital in regulating the global climate and mitigating the extinction crisis.

̽��ֱ��research was funded primarily by the Tezos Foundation. It was conducted by researchers at the Cambridge Centre for Carbon Credits.

Reference: Balmford, A et al.: ‘Realising the social value of impermanent carbon credits.’ Nature Climate Change, October 2023. DOI: 10.1038/s41558-023-01815-0

Degraded soils mean tropical forests may never fully recover from logging

jg533 — Tue, 17 Dec 2019 00:01:00 +0000

Trees of recovering tropical forests were found to have tougher leaves, with lower concentrations of the nutrients phosphorus and nitrogen – both essential for plant and tree growth - than trees of old-growth forests. This suggests that multiple cycles of logging and recovery irreversibly remove phosphorus from the forest system, and are pushing the nutrient content towards ecological limits.

“Old-growth tropical forests that have been the same for millions of years are now changing irreversibly due to repeated logging,” said Dr Tom Swinfield, a plant scientist in the ̽��ֱ�� of Cambridge Conservation Research Institute, and first author of the paper published in the journal Global Change Biology.

Soil nutrients including phosphorus come from rocks, and are taken up by trees through their roots. Cutting down the trees causes these nutrients to be lost through soil erosion, gas emissions, and removal of nutrients in the extracted timber. ̽��ֱ��researchers estimate that as much as 30% of the available phosphorus in the soil is being removed from tropical forest systems by repeated logging.

“We see that as the logged forests start recovering, they’re actually diverging from the old growth forests in terms of their leaf chemistry and possibly also species composition, as the amount of available nutrients goes down,” said Swinfield. “At the moment the trees can cope, but the fact that they’re changing indicates phosphorus levels in the soil are dropping. This could affect the speed at which forests recover from future disturbances.”

̽��ֱ��researchers created high definition images of a forest landscape in north-eastern Borneo using LIDAR-guided imaging spectroscopy from an aircraft. This is a method of remote sensing, using a laser scanner and high fidelity camera, which takes hundreds of measurements across the light spectrum. They combined this information with nutrient measurements from 700 individual trees in the forest. This allowed them to map the concentrations of nutrients in the trees’ leaves over an area containing repeatedly logged forest and old-growth forest, and compare the two.

This is the first landscape-scale study of how leaf function changes in response to logging. Selective logging is carried out extensively across millions of hectares of forest in the tropics, so that degraded forests are now more widespread than old-growth forests. ̽��ֱ��study suggests that each consecutive harvest reduces the level of nutrients in the system, and newly established trees have to adapt to conserve the scarce resources available to them.

“Phosphorus limitation is a really serious global issue: it’s one of the areas where humans are using a vital resource beyond sustainable levels,” said Professor David Coomes, Director of the ̽��ֱ�� of Cambridge Conservation Research Institute, who led the project. ̽��ֱ��researchers found that differences from old-growth forest become more pronounced as logged forests grow larger over time, suggesting exacerbated phosphorus limitation as forests recover.

This research was funded by the Natural Environment Research Council.

Reference
Swinfield, T. et al: ‘Imaging spectroscopy reveals the effects of topography and logging on the leaf chemistry of tropical forest canopy trees.’ Global Change Biology, Dec 2019. DOI: 10.1111/GCB.14903.

Continually logging and re-growing tropical forests to supply timber is reducing the levels of vital nutrients in the soil, which may limit future forest growth and recovery, a new study suggests. This raises concerns about the long-term sustainability of logging in the tropics.

Phosphorus limitation is a really serious global issue: it’s one of the areas where humans are using a vital resource beyond sustainable levels.

David Coomes

Greenpeace / Kate Davison

Logging in the rainforest of Kalimantan

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Offset markets: new approach could help save tropical forests by restoring faith in carbon credits

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Degraded soils mean tropical forests may never fully recover from logging