The Four Requirements for Effective Nature-Based Climate Solutions Involving Carbon Offsets, According to New Research

  

     Carbon offsets have long been criticized as vulnerable to manipulation, errors, and questionable emissions reduction accounting. The offsets are very often associated with and generated by nature-based climate solutions (NbCS). According to American University’s factsheet, NbCSs:

“…involve conserving, restoring, or better managing ecosystems to remove carbon dioxide (CO2) from the atmosphere. Examples include allowing forests to regrow, restoring coastal wetlands, and switching to restorative agricultural practices, such as cover crop rotation, that support healthy soils. These ecosystems reduce climate change by capturing CO2 from the air and sequestering it in plants, soils, and sediments. They also provide a wide range of other important benefits, such as cleaner air and water, economic benefits, and increased biodiversity.”

     They can be classified into those that prevent or avoid emissions and those that draw down or remove emissions. For example, preventing deforestation prevents emissions, and reforestation draws down emissions. Along with nature-based solutions, there are engineered solutions such as CCS. 

     There are also co-benefits and concerns about NbCSs that must be considered and accounted for, summarized below from American University's factsheet.

     A 2017 PNAS study concluded that NbCSs could mitigate up to 20% of global emissions for a 2 °C by 2050 climate target. That would require quite a lot of projects, most of them difficult to quantify. Those projects would also require accurate measurement, verification, and reporting (MVR). Each should be evaluated according to various offset protocols. This raises the cost of projects, but it is necessary to show some level of proof that the projects are working as intended. An issue for land-based solutions, such as soil sequestration, is how long the carbon is retained in the soil. This depends on many factors, notably the future land uses and what happens to the land. Thus, I would say the estimate from the PNAS paper is overly optimistic by a large margin. The chart below, from the PNAS paper, shows the mitigation potential of different NbCSs. Below that is a chart showing and comparing emissions avoidance vs. emissions drawdown for forests, grasses, and wetlands. 

     Of course, the most cost-effective solutions will be pursued the most, so comparing costs is important. A 2024 paper in Nature Climate Change explored the underlying science of NbCSs. The paper explored and compared 43 NbCS pathways, noting differences in certainty, as noted in the abstract below. The graph below shows the scale of impact vs. level of uncertainty for each pathway. This is followed by a table showing the number of carbon credits issued for each category of NbCS.

 

Table 1 Credit issuance by NbCS category

The Four Requirements for Effective Nature-Based Climate Solutions

     New research led by the University of Utah's Wilkes Center for Climate Science & Policy analyzes different strategies for improving NbCSs. According to Phys.org, the study:

“…identifies four components where nature-based climate actions have not lived up to their billing and proposes reforms to improve their performance and scalability.”

     Since trees and forests offer the most effective NbCS, even if they can be hard to quantify at times, that is the focus of the paper. One of the paper’s authors noted the widespread problems with carbon accounting in evaluations of offsets. The example given is albedo. While it can reduce and even negate emissions benefits in some cases, there is no accounting for it in carbon offset evaluation. The study came up with four critical factors for successful NbCSs, shown below.

     The study also came up with a slightly different approach, emphasizing contributions to well-verified and well-quantified solutions as opposed to choosing less-verifiable, less-quantifiable solutions. These can be legally argued better, as well as leaving fewer doubts.

     Factor 1- ensuring a cooling effect, is given the albedo example again. If one plants conifers in a snow-covered area, the change in albedo from the reflecting snow to the dark-colored trees that absorb heat in the day might cancel out the emissions benefits. Factor 2 is simply ensuring the climate benefits of an action relative to not doing the action. For example, if a forest is being preserved that was not likely to be cut down, there is no real change, and any credits issued would not have real benefits. Factor 3 involves “leakage” of the carbon back into the atmosphere, either through land-use changes or simply moving the land disturbance from one place to another. Factor 4 is the durability of the solutions. The preference is that the carbon will remain sequestered for at least a century. Unfortunately, natural disasters such as wildfires, droughts, pests, diseases, and anything that kills trees can also negate an NbCS, so the likelihood of these high-risk disturbance events also needs to be considered. Thus, any NbCS should be able to prove that it deals with these four requirements for effectiveness. According to Phys.org:

"You have to know how big the risks are, and you have to account for those risks in the policies and programs," Anderegg said. "Otherwise, basically you're going to lose a lot of that carbon storage as climate change accelerates the risks."

“The methods now in place, known as "buffer pools," to account for these risks are not robust or rigorous currently, according to research by Anderegg's lab, which expects to release a study soon highlighting potential fixes.”

     An article about the research in Anthropocene Magazine notes:

“Currently, nature-based climate solutions and forest carbon markets are struggling to deliver effective climate mitigation,” says study team member William Anderegg, a forest ecologist at the University of Utah. “Our study provides a roadmap to improve these programs in four critical areas and also proposes a novel funding mechanism that could support projects without carbon offsets.”

“The study focuses on forests because of their ability to capture such large volumes of carbon. But forests don’t just store carbon; they can also change patterns of cloud cover, release volatile organic compounds and aerosols, and alter the color of the landscape. All of these changes can have either a warming or a cooling effect. So the first requirement for an effective project is to make sure that it results in net cooling, the researchers say.”

     The researchers' proposed contribution approach vs. an offset approach is simply a suggestion for companies to focus on the most accepted forms of mitigation, essentially putting a carbon tax on themselves to reduce emissions. Voluntary emissions reduction is important in that it avoids the pressure and some of the regulatory requirements of compliance-based emissions reduction. The paper abstract is below.

    

 

References:

 

Carbon 'offsets' aren't working: Researchers offer a 'roadmap' to improve nature-based climate solutions. Science X staff. Phys.org. July 30 2025. Carbon 'offsets' aren't working: Researchers offer a 'roadmap' to improve nature-based climate solutions

What are Nature-Based Solutions? American University. Factsheet. 2025. Fact Sheet: Nature-Based Solutions to Climate Change | American University, Washington, DC

Towards more effective nature-based climate solutions in global forests. William R. L. Anderegg, Libby Blanchard, Christa Anderson, Grayson Badgley, Danny Cullenward, Peng Gao, Michael L. Goulden, Barbara Haya, Jennifer A. Holm, Matthew D. Hurteau, Marysa Lague, Meng Liu, Kimberly A. Novick, James Randerson, Anna T. Trugman, Jonathan A. Wang, Christopher A. Williams, Chao Wu & Linqing Yang. Nature volume 643, pages1214–1222 (July 30, 2025). Towards more effective nature-based climate solutions in global forests | Nature

Expert review of the science underlying nature-based climate solutions. B. Buma, D. R. Gordon, K. M. Kleisner, A. Bartuska, A. Bidlack, R. DeFries, P. Ellis, P. Friedlingstein, S. Metzger, G. Morgan, K. Novick, J. N. Sanchirico, J. R. Collins, A. J. Eagle, R. Fujita, E. Holst, J. M. Lavallee, R. N. Lubowski, C. Melikov, L. A. Moore, E. E. Oldfield, J. Paltseva, A. M. Raffeld, N. A. Randazzo, …S. P. Hamburg Show authors. Nature Climate Change volume 14, pages402–406 (March 21, 2024). Expert review of the science underlying nature-based climate solutions | Nature Climate Change

Most forest carbon offset schemes fail. Here’s a four-step road map to fix them. Sarah DeWeerdt. Anthropocene Magazine. August 5, 2025. Most forest carbon offset schemes fail. Here’s a four-step road map to fix them.

Natural climate solutions. Bronson W. Griscom, Justin Adams, Peter W. Ellis, Joseph Fargione. et.al. October 16, 2017 PNAS. Vol. 114 | No.44) 11645-11650. October 16, 2017. Natural climate solutions | PNAS