December 2025 Science Summary

Greetings,

This month I am summarizing three science papers about climate change plus I wanted to share a cool idea I recently learned about.

Here's the cool idea: recent research in Colorado (by Julia Kintsch from ECO-resolutions among others) has found that simply adding lines of woody debris underneath underpasses (see the photo above) boosted underpass use by small mammals. Cover features composed of salvaged logs and branches with sufficient interstitial space through which small animals can move doubled the number of species documented using large bridges under an interstate to access habitats on either side. They detected 17 species using the cover features, including small mammals, amphibians, reptiles, and the federally threatened Preble’s meadow jumping mouse. This is a really cheap intervention worth trying out more broadly, please help spread the word!

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FORESTATION (REFORESTATION AND AFFORESTATION):
Wang et al. 2025 finds that earlier estimates of how much of the worth could be forested were much too high. One the one hand - this means we can't count on trees to do as much sequestering as some models hoped for. But as one of the authors (Susan Cook-Patton) points out (in this excellent post) the larger area wasn't feasible anyway, so this smaller estimate gives us more actionable priorities for planting. She also notes that while reducing fossil fuels (and protection of acutely threatened forests) is higher priority than forestation, we absolutely need all of the above. Note: reforestation is restoring trees where they used to be, afforestation is planting trees in what used to be grasslands or other ecosystems, forestation is both.

CLIMATE CHANGE - CARBON MARKETS AND ALBEDO:
Riley et al. 2025 have an update on an issue I've written about several times: that the albedo of trees (how much they reflect sunlight compared to bare soil) can reduce or even fully negate the climate benefit of trees in some cases. They looked at 172 tree planting projects in the voluntary carbon market to see how carbon credits issued compared to true climate impact once albedo was considered. On average 18% of the issued credits shouldn't have been, and 25% of the projects offered more than double the credits they should have once albedo was considered. 12% of the projects (a subset of that 25%) were even net harmful (representing 30% of total credits issued). In good news, 9% of projects actually had more benefit than estimated, and over half of projects had 0-25% of their issued carbon credits negated by albedo. This is important to get right, but a shortcut is to focus protection and forestation in more tropical places while avoiding areas with heavy snow cover and/or very light-colored soils (the pink places in Fig 2a are good to avoid).

DEFORESTATION AND CLIMATE CHANGE:
Franco et al. 2025 looks at how both deforestation and climate change have affected temperature and precipitation in the Amazon. Losing trees not only increases atmospheric carbon which drives global warming, for tropical forests in particular it also increases LOCAL warming and especially decreases water cycling. They found that deforestation caused 3/4 of the decline in dry season precipitation but only 17% of the increase in temperature. This is similar to other work which has found deforestation has delayed the onset of the rainy season in the Cerrado (Spera et al. 2016) and Pantanal (Lázaro et al. 2020).


REFERENCES:
Franco, M. A., Rizzo, L. V., Teixeira, M. J., Artaxo, P., Azevedo, T., Lelieveld, J., Nobre, C. A., Pöhlker, C., Pöschl, U., Shimbo, J., Xu, X., & Machado, L. A. T. (2025). How climate change and deforestation interact in the transformation of the Amazon rainforest. Nature Communications, 16(1), 7944. https://doi.org/10.1038/s41467-025-63156-0

Lázaro, W. L., & Oliveira-júnior, E. S. (2020). Thematic Section : Opinions about Aquatic Ecology in a Changing World Climate change reflected in one of the largest wetlands in the world : an overview of the Northern Pantanal water regime. Acta Limnologica Brasiliensia, 32, 8.

Riley, L. M., Cook-Patton, S. C., Albert, L. P., Still, C. J., Williams, C. A., & Bukoski, J. J. (2025). Accounting for albedo in carbon market protocols. Nature Communications, 16(1), 8810. https://doi.org/10.1038/s41467-025-64317-x

Spera, S. A., Galford, G. L., Coe, M. T., Macedo, M. N., & Mustard, J. F. (2016). Land-use change affects water recycling in Brazil’s last agricultural frontier. Global Change Biology, 22(10), 3405–3413. https://doi.org/10.1111/gcb.13298

Wang, Y., Zhu, Y., Cook-Patton, S. C., Sun, W., Zhang, W., Ciais, P., Li, T., Smith, P., Yuan, W., Zhu, X., Canadell, J. G., Deng, X., Xu, Y., Xu, H., Yue, C., & Qin, Z. (2025). Land availability and policy commitments limit global climate mitigation from forestation. Science, 389(6763), 931–934. https://doi.org/10.1126/science.adj6841

Sincerely,
 
Jon