November 14, 2018
The lush grasslands and natural landscapes of the United States may be the key to fighting climate change, according to a new study that features research from the University of Wisconsin—Madison. Published in Science Advances, the study shows that low-cost, natural climate solutions that encourage the growth and retention of grasslands, wetlands, and forests, can contribute to a significant decrease in carbon emissions. In fact, thanks to the natural carbon absorption and storage properties of the plants found in these natural areas, the study estimates that improved maintenance of this land would allow for the annual absorption of one fifth of all U.S. greenhouse gas emissions, which is equivalent to emissions from all U.S. vehicles.
The new study, led by The Nature Conservancy in collaboration with 21 institutional partners, is the first to analyze the climate-related benefits of grasslands and coastal wetlands alongside forests and agriculture, which are areas that have been more heavily studied. This is thanks, in part, to the efforts of UW-Madison co-authors, Associate Researcher and Nelson Institute alum Dr. Tyler Lark and Geography graduate student, Seth Spawn. Lark and Spawn – both researchers in the Nelson Institute’s Center for Sustainability and the Global Environment (SAGE)– led the analyses of grassland conservation and restoration and its potential to fight climate change.
“We're really excited about this study as it brings together leading expertise from all these individual climate solution pathways – from forest and fire management to cover crops and wetlands – and for the first time lines them up, allowing us to compare apples to apples,” said Lark. "It reveals what the priorities are and encourages a united effort by showcasing what can be accomplished, collectively. It's a great example of something we could learn only by breaking out of traditional research silos and reaching across scientific disciplines.”
To study the specific impact of grasslands, Lark and Spawn utilized new models and data including satellite images that showed on-the-ground activity as well as carbon levels in the soil. By combining data from several sources and applying their own novel modeling tools, Lark and Spawn were able to see where grassland is being converted or lost and how much carbon moves into the atmosphere as a result of that change. Using this information, they calculated the overall cost and carbon sequestration achievable through grassland conservation and restoration throughout the U.S. Ultimately, the research showed that of the 21 land management solutions studied, maintaining grassland is among the most impactful, cost effective, and scalable solutions to mitigating climate change.
“At a time when we increasingly see and feel the negative effects of climate change and the challenges it poses, this research squarely focuses on the solutions and opportunities we have on hand to mitigate climate change,” said Lark. “What we found is that there are a number of relatively cheap and easy solutions, such as maintaining and restoring grasslands and forests, that are win-wins for producers and land managers as well as society and the environment.”
In addition to combating global warming, many of the proposed natural climate solutions come with co-benefits of improving biodiversity, soil health, and water quality.
“Having grassland near a field can boost agricultural production,” said Lark. “It promotes biodiversity, increases pollination, and is home to predators that help suppress potential pests."
Meanwhile, these solutions also help the broader community. "Carbon emissions are costly to society” added Spawn, “As the primary cause of global climate change, these emissions can be detrimental to agricultural productivity and human health. Keeping grasslands on the landscape and their carbon in the ground can therefore be beneficial to everybody.”
Grassland, which is categorized as any managed or natural area dominated by herbaceous or non-woody vegetation, can be found throughout the United States. This vegetation, which often includes tall grasses and prairie plants, is well-known for its ability to absorb and store carbon in its roots and in the soil, but research shows that grassland is disappearing from the landscape. In fact, studies estimate that grassland is currently being lost at a rate of over one million acres per year. This loss is particularly detrimental as research suggests that about 28 percent of the carbon being stored in grassland is released into the atmosphere when the natural grassland is converted for other uses such as cropland.
While maintaining grassland poses the largest opportunity of the 11 agriculture-focused solutions studied, the new work also highlights the benefits and potential of cover crops, which are grains, grasses or legumes that are planted alongside or in rotation with a cash crop. Cover crops are not meant to be harvested, but instead offer a natural solution to issues such as soil erosion, weeds, and pests. While not entirely the same as grassland, cover crops were shown to help with carbon sequestration and are another viable way to reduce carbon in the atmosphere where maintaining grassland is not possible.
“We tend to think more about technological solutions to climate change,” said Spawn. “But this study demonstrates that low-cost, scalable solutions can be readily achieved by tweaking the ways we manage our lands.”
This realization has been significant for cities and states looking to mitigate climate change on a budget. In fact, despite its recent release, the study has already garnered a great deal of attention with results being presented at the Global Climate Action Summit, September 12–14, 2018 in San Francisco, California. There, scientists and public leaders met to discuss solutions such as this and other ways to keep the global temperature increase below the two degrees Celsius that was set forth by the Paris Climate Agreement.
“With the significant loss of grassland on an annual basis, we’re not yet headed in the right direction and every day that we don’t act, emissions continue,” said Lark. “Fortunately, we now know the impact of this and other natural climate solutions; so it’s time to begin implementing.”
Want to learn more about climate change mitigation potential and the cost of each select pathway in your area? Check out the latest tool from The Nature Conservancy and other Nature4Climate partners at: https://nature4climate.org/u-s-carbon-mapper/