Shelby C. McClelland

Good 🧵

Friendly amendment: stop burning fossil fuels (responsible for 2/3 of historical CO2 emissions), and also stop deforestation & land-use change (the other 1/3).

And if you do something that reduces fossil CO2 but increases land use and deforestation EVEN MORE, that’s an anti-solution. Avoid.

To my co-author and PhD Advisor, Meagan Schipanski, THANK YOU! You let me dream up this project and supported me in diving deep into this research during my PhD. I learned so much through the ups and downs, and I am so grateful for the freedom to explore and grow as an ecologist.

While this work starts to broaden our mechanistic understanding of how compost contributes to soil carbon sequestration, we absolutely need more data, better analyses, and longer-term studies to understand carbon flows (and persistence of this new carbon) in managed grassland ecosystems! 7/N

To us, this suggests that the microbial community was more responsive to plant over compost-derived inputs. It also indicates that microbial-derived inputs were more important for building soil organic carbon in this managed grassland. 6/N

Figure 5 from the article. Image is a conceptualized drawing of the paths from different variables to soil organic carbon (SOC).

We used a path analysis to test our hypothesis. But what we found surprised us! Plants only indirectly increased soil organic matter; their effect was entirely mediated through the soil microbial community, especially bacteria. 5/N

Figure 3 from the article. Image is four panels of faceted (by year) box and whisker plots of soil microbial community responses.

Plants responded immediately, both in terms of productivity and community composition. Microbes, however, were slower to respond. We only observed community differences in the final growing season. There were also differences in microbial functional diversity. 4/N

Image is a photo of lead author, Shelby McClelland, conducting a plant transect in a pasture.

Over three growing seasons in northern Colorado, we measured plant growth and diversity, microbial community composition and function, and soil carbon. We hypothesized that plants and microbes jointly contributed to the soil carbon response.

What did we find? 3/N

Infrequent compost applications increased plant productivity and soil organic carbon in irrigated pasture but not degraded rangeland Improved agricultural soil management can facilitate the removal of carbon dioxide from the atmosphere to help keep planetary warming at or below 2 °C…

Infrequent compost applications in managed grasslands can boost soil organic carbon stocks–even after discounting the carbon from the compost itself!

Read our earlier work 👉 tinyurl.com/a3nzcwbs

But! We still don’t fully understand how plants and microbes interact to build this carbon. 2/N

Soil organic carbon sequestration mediated by plant–microbe interactions after compost application Organic amendments like compost can enhance soil health and climate change mitigation in managed grassland ecosystems. We previously demonstrated in a northern Colorado cool-season pasture that infre...

✨ The LAST chapter of my dissertation is published! ✨

How do plant-soil feedbacks support carbon sequestration in grasslands receiving compost?

Here’s what we learned ⬇️

tinyurl.com/muk2ufe5

Our Research Briefing is now out in Nature Climate Change!

We examine the spatially variable tradeoffs between climate change mitigation and crop yields under regenerative agriculture. Globally, safeguarding crop yields will substantially lower mitigation potential.

Read more ➡️ rdcu.be/eo6lE

Scientists accuse New Zealand and Ireland of trying to cover up livestock emissions ‘Accounting trick’ to support methane-emitting sectors undermines fight against climate change, say researchers

This is incredibly unfair: high-income nations with large dairy sectors are looking to adopt a "no additional warming" target, avoiding the methane cuts needed to meet international targets and pledges.

We have written an open letter to the NZ PM and I spoke to the FT👇🧵

www.ft.com/content/2ea6...

Great coverage in the Cornell Chronicle of our paper including quotes from me and @dominicwoolf.bsky.social.

Read here ➡️ tinyurl.com/yfmwy34h

Soils Revealed Soils Revealed platform lets you see past soil organic carbon losses and opportunities for future gains, to manage soil health that helps mitigate climate change, promote clean water and biodiversity.

If you want to explore some earlier, related data, check out these high resolution soil organic carbon maps from my colleagues over at SoilsRevealed.org. 12/N

Scientists Identify Ways to Minimize Tradeoffs Between Crop Yields and Climate Benefits Research highlights where and how regenerative farming could lead to win-wins for climate-change mitigation and crop production

If you don’t have time for all the details, but want to learn more about our key findings, check out our accompanying press release from NYU, www.nyu.edu/about/news-p.... Later I'll post the link to our Research Briefing from @natureportfolio.nature.com 11/N

A special shoutout to @dominicwoolf.bsky.social @matthewhayek.bsky.social for your mentorship and support! 10/N

This study came out of an amazing collaboration between @cornelluniversity.bsky.social, @newyorkuniversity.bsky.social, CSU, @nature.org, @envdefensefund.bsky.social, and @woodwellclimate.bsky.social. Thanks to my collaborators who helped get this massive modeling effort to the finish line! 9/N

This research opens new possibilities for regenerative agriculture to provide climate and yield benefits, but shows its limits as a key climate solution. What food we produce is as important as how we produce it. Food system decarbonization must entail greater scrutiny of GHG-intensive foods 🥩🍗 8/N

We provide spatially-explicit adoption recommendations based on Pareto-optimal outcomes that balance climate and yield goals. By maintaining crop yields, we find that the maximum GHG mitigation potential of cover crops, no-till, and residue is about 85% lower than if we ignore yield outcomes. 7/N

Four panel figure of the top five features for predicting medium-term, 2016–2100, favourable outcomes ranked by mean absolute SHAP value estimated from random forest models. Corresponds to Figure 3 in the paper.

What’s driving these outcomes? We used explainable machine learning to show that win-win outcomes are more likely in soils with higher clay content and lower initial soil nitrogen availability. Identifying these conditions helps us create a clearer decision-framework for adoption on farms. 6/N

Grass cover crops with no-till have the highest GHG mitigation potential (0.49 Pg CO2-eq yr-1) but lower crop yields (0.1 Pg yr-1) through 2100. Meanwhile, legume cover crops with no-till has clear crop yield benefits (0.28 Pg yr-1) over this timeframe but much lower mitigation potential. 5/N

Four panel map of GHG and crop yield responses to natural climate solutions on croplands. Corresponds to Extended Data Figure 3 in the paper. Colors indicate lower, no difference, or higher yields and emissions, no difference, or GHG mitigation. For quantitative results, see Extended Data Fig. 1. Panels are Grass CC (a,), Grass CC + Ntill (b), Legume CC (c), and Legume CC + Ntill (d). Scenario: cover crop (CC); and, no-tillage (Ntill). Base map data in a–d from The World Bank under a Creative Commons license CC BY 4.0.

One of our key findings is that win-win outcomes from adopting these practices are not as common as we once thought. Our analysis shows that it is difficult to maximize GHG mitigation and crop yield benefits, especially over longer time horizons, i.e., 2100. 4/N

We used DayCent to model future soil organic carbon, nitrous oxide, and crop yield responses to cover crops, no-till, and residue retention relative to fallow and tillage in maize, soybean, and wheat croplands. We included spatially-explicit management information and accounted for uncertainty. 3/N

The global food system contributes to ~1/3 of anthropogenic GHGs. Soil emissions alone are estimated to have contributed to 15% of global climate warming. At Cornell, we investigated how soil management impacts GHGs and crop productivity—because with rising food demand we must safeguard yields. 2/N

Managing for climate and production goals on crop-lands - Nature Climate Change Climate mitigation through natural climate solutions in crop-lands may be a way to reconcile climate goals with food security. However, here the authors show that some natural climate solution practic...

🚨New paper alert🚨

We show that maintaining crop yields lowers the global climate benefits of natural climate solutions on croplands. But, we highlight where win-win opportunities exist for these practices to contribute to climate and production goals. 1/N

www.nature.com/articles/s41...

😡🤬

Happening in less than an hour!

Our research asks if adopting intensification strategies and mitigation technologies (without lowering meat + milk demand) are *enough* to meet CH4 targets at global and regional scales

Come by to find out if they are (or not) if you’re here at #AGU24!

If you won't be at AGU this year, and you're interested in learning more about our work, feel free to reach out!

I'll be presenting preliminary findings from ex-ante modeling I've conducted at NYU with @matthewhayek.bsky.social through the Center for Environmental and Animal Protection and the Dept. of Environmental Studies.

Can 2050 cattle CH4 mitigation targets be met through intensification and mitigation technologies? Are these strategies enough to reduce CH4 without lowering consumption of meat and milk?

Come see me at my poster during #AGU24 (GC13L-0336) on Monday, Dec. 9 from 13:40-17:30 EST to find out!