Tuesday, October 1, 2019

October 2019 science journal article summary

Monstera deliciosa

This month I focused mostly on climate change. How does the picture above relate? It doesn't, but this fruit rind reminded me of spatial planning hexes which made me smile (bonus points if you can guess the fruit it came from).

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Last month I sent 10 articles with advice on how to improve the impact of research. Edwards & Meagher 2019 offers a framework you can use to evaluate that impact. I'd recommend focusing on Table 1, which has an excellent list of questions to consider. They can help to better understand what changed (or what you hope will change, since setting impact goals up front is ideal), and how / why it changed (or didn't). The authors argue that conceptual models or results chains (theory of change diagrams) are often useless because sometimes there are interesting feedback loops or non-linear aspects. But while this approach can be flawed and has limits, I've found that situations where it's unhelpful are the exception rather than the rule, and the authors don't make a strong case otherwise. I also didn't find the results where the impact framework was applied to case studies to be very useful, but I really like the questions they asked up front.

Smith et al. 2019 evaluates how six options for greenhouse gas (GHG) removal compare in how well they relate to the Sustainable Development Goals (positively and negatively). They look at reforestation (and afforestation), wetland restoration (coastal and freshwater), soil carbon sequestration, biochar, terrestrial enhanced weathering, and bioenergy w/ carbon capture and storage (BECCS). It's a dense paper worth reading for all the info, especially the figures which are great summaries. One interesting take-away is that restoring wetlands and boosting soil carbon are 'no regrets' strategies with almost entirely positive impacts (although soil as a mitigation strategy has some uncertainty and limits).

Busch et al. 2019 maps where tropical reforestation (and avoided deforestation) is practical at different carbon prices (they report mostly on $20/t CO2e and $50/t). Fig 2 is a great summary of where the most opportunity is. Overall at $20/t they estimate 60.8 Gt CO2e of opportunity (55.1 avoided deforestation, 5.7 reforestation), and at $50/t they estimate 123.4 Gt opportunity (108.3 avoided deforestation, 15.1 reforestation). One interesting finding is that while avoided deforestation is much more cost-effective in general, in 21 countries (mostly African) there is more low-cost opportunity for reforestation. This highlights the need to avoid a one-size-fits-all approach.

There has been considerable discussion on how climate change will impact crop yields. Most predicted impacts are negative (drought stress, less consistent rain, and increasing pests) although some are positive (carbon fertilization, and shifting some marginal lands to be more suitable for crops). Ray et al. 2019 looks at 40 years of global weather data & crop yield data for the top 10 crops, and concludes that those impacts have already started to happen. They estimate that we've probably already lost ~1% of calories we would have had without climate change. Palm oil had the most lost potential, while soy has benefited overall. Check out Figure 1 which maps estimated impacts by each crop around the world.

Roque et al. 2019 is the first test in vivo of the seaweed Asparagopsis to reduce enteric methane from cattle, which is a big deal. The higher dose cut cattle methane emissions per unit of milk by 60% (despite slightly lower weight gain and milk production). Note that all studied cattle were also fed more fiber than usual, which could have increased the size of that effect. More research is needed to: replicate this, look at beef cattle, fully account for GHG changes, and explore impacts on meat and milk quality.

Walsworth et al. 2019 argues that to help species adapt to climate change,  we should focus on protecting a diversity of habitats and genetic differences in populations (plus connectivity between habitat), rather than focusing on 'climate refugia' (colder areas species can move to). This can enable heat-resistant populations to move to other areas where they can interbreed and help other populations adapt. It's a reasonable argument, but note that it's based on a very simple coral reef model. So future work needs to look at this empirically and test it on land and in fresh water.

Realmonte et al. 2019 looked at the global potential impacts of direct air carbon capture and storage (DACCS) tech (splitting out more and less mature versions). They compare scenarios using only reforestation vs. also including bioenergy w/ carbon capture and storage (BECCS) vs. also including DACCS. Their key findings are that having DACCS widely available and effective will help to both meet Paris goals, and to reduce total costs of mitigation. But we can't assume that will happen given the tech challenges and need for investment. In a few places the paper has confusing / misleading language about DACCS allowing delays in mitigation, but elsewhere they make it clear that's not their intent.

Cameron et al. 2017 looks at how much natural habitat can contibute to California's climate goals (~9% of their goals under a moderate scenario). They found the biggest impact from improved forest management to boost C stocks (61% of total potential, from things like longer rotations and higher tree density), followed by reforestation (14%). Some pathways like compost amendments may have undesirable side-effects on biodiversity, and they didn't include other natural climate solutions like changes to agricultural management.

Busch J, Engelmann J, Cook-Patton SC, Griscom BW, Kroeger T, Possingham H, Shyamsundar P. 2019. Potential for low-cost carbon dioxide removal through tropical reforestation. Nature Climate Change 9: 463–466.

Cameron, D. R., Marvin, D. C., Remucal, J. M., & Passero, M. C. (2017). Ecosystem management and land conservation can substantially contribute to California’s climate mitigation goals. Proceedings of the National Academy of Sciences, 201707811. https://doi.org/10.1073/pnas.1707811114

Edwards, D. M., & Meagher, L. R. (2019). A framework to evaluate the impacts of research on policy and practice: A forestry pilot study. Forest Policy and Economics, (August). https://doi.org/10.1016/j.forpol.2019.101975

Ray, D. K., West, P. C., Clark, M., Gerber, J. S., Prishchepov, A. V., & Chatterjee, S. (2019). Climate change has likely already affected global food production. PLOS ONE, 14(5), e0217148. https://doi.org/10.1371/journal.pone.0217148

Realmonte, G., Drouet, L., Gambhir, A., Glynn, J., Hawkes, A., Köberle, A. C., & Tavoni, M. (2019). An inter-model assessment of the role of direct air capture in deep mitigation pathways. Nature Communications, 10(1), 3277. https://doi.org/10.1038/s41467-019-10842-5

Roque, B. M., Salwen, J. K., Kinley, R., & Kebreab, E. (2019). Inclusion of Asparagopsis armata in lactating dairy cows’ diet reduces enteric methane emission by over 50 percent. Journal of Cleaner Production, 234, 132–138. https://doi.org/10.1016/j.jclepro.2019.06.193

Smith, P., Adams, J., Beerling, D. J., Beringer, T., Calvin, K. V., Fuss, S., … Keesstra, S. (2019). Impacts of Land-Based Greenhouse Gas Removal Options on Ecosystem Services and the United Nations Sustainable Development Goals. Annual Review of Environment and Resources, 44(1), 1–32. https://doi.org/10.1146/annurev-environ-101718-033129

Walsworth TE, Schindler DE, Colton MA, Webster MS, Palumbi SR, Mumby PJ, Essington TE, Pinsky ML. 2019. Management for network diversity speeds evolutionary adaptation to climate change. Nature Climate Change 9: 632–636. http://dx.doi.org/10.1038/s41558-019-0518-5



p.s. If you'd like to keep track of what I write as well as what I read, I always link to both my informal blog posts and my formal publications (plus these summaries) at http://sciencejon.blogspot.com/

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