Energy Innovation partners with the independent nonprofit Aspen Global Change Institute (AGCI) to provide climate and energy research updates. The research synopsis below comes from AGCI Executive Director James C. Arnott. A full list of AGCI’s updates is available online.
Mangroves, like these pictured in Singapore’s Sungei Buloh Wetland Reserve, are often considered a biodiverse-rich ecosystem that also affords climate protection. Photo: Disha Yadav/ Unsplash
For many climate advocates preparing for this year’s COP29 in Baku, it might be a surprise to learn that a different annual Conference of Parties (COP) just wrapped in Cali, Columbia. This recent COP, also a pillar of global progress on sustainability, focused not primarily on climate change but on biological diversity.
Unfortunately, the climate crisis and biodiversity loss are too often considered separately from one another. As a result, the science about and potential solutions for each are typically explored through distinct channels, sometimes even competing with one another for attention and resources rather than navigating toward a more holistic path to sustainability.
Climate change presents a growing threat to biodiversity. Yet healthy and diverse living systems can play an important role in reducing future climate impacts by drawing down carbon in the atmosphere or helping communities build resilience. Accordingly, it’s worth looking at recent research for fresh insights on climate change and biodiversity, which can demonstrate the value of more integrated solutions.
At the most basic level, greater awareness of climate change impacts on nature heightens the case for urgency on reducing emissions. Some long-considered policies for biodiversity protection, like land use protections, may be emboldened or tweaked to capture benefits for climate solutions. But moving in this direction will require a more integrated approach to both policy and research. Though this has been largely missing in recent decades, there are glimmers of hope on the horizon.
Pinning down the magnitude of climate impacts on biodiversity
Historically, humans have impacted biodiversity in myriad ways, from land use change (e.g., clearing natural habitats for cropland) and resource extraction (e.g., fishing or logging) to the spread of invasive species (e.g., Burmese pythons in Florida overconsuming local fauna) and the introduction of pollution and toxins (e.g., PFAS and other “forever chemicals”).
Climate change aside, the consequences of these impacts on biodiversity is profound: The rate of species extinctions in the 20th century alone has been estimated at 30 to 120 times the rate in the previous 66 million years (based on the fossil record), on par with past mass extinction events.
Climate change now presents an added threat to the diverse web of life. Rising temperatures can shrink suitable habitats, drought can spur tree mortality, imperiling forest health, and ocean acidification, driven by elevated ocean uptake of CO2 emissions, intensifies damage to coral reefs and other marine species around the globe.
Studies attempting to quantify how much climate change will affect species extinction –– just one aspect of biodiversity –– have a hard time finding agreement or high confidence owing to the underlying difficulties in monitoring, let alone predicting, the health and interactions between the estimated nine million species on Earth. However, a new review by John J. Wiens and Joseph Zelinka from the University of Arizona examined a range of studies over the past several decades that estimated the climate impacts on species loss for plant and animal species.
Considering a worst-case, high-end climate change scenario, Wiens and Zelinka estimate a potential 16 percent of species loss due to climate change (Figure 1). But even if the planet avoids worst case projections or if species manage to be more climate-resilient than current models anticipate, nearly any magnitude of species loss is sobering given the finality that accompanies extinction and the oftentimes unknown ripple effects that the removal of even a single species can have on the web of life.
Figure 1. Projections of species loss due to climate change from a range of studies, with “this study” (rightmost bar) offering an updated projection based on a new review by Wiens & Zelinka, 2024. Most studies assume species go extinct when 100 percent of their geographic range become climatically unsuitable, based on species distribution modeling. Many studies gave a range of estimates across different climate change scenarios. These are presented as a solid bar spanning the highest and lowest estimates, the highest generally corresponding to the RCP 8.5 scenario with a ~4°C increase. Figure and adapted caption text from Wiens & Zelinka, 2024.
Combining existing tools yields fresh insights
Thinking about climate change and biodiversity together can help us transcend the bleak tally of potential damages. Modeling tools developed to explore climate change and biodiversity loss can be combined and compared to assess the issues as a more dynamic problem set, thus illuminating the connections.
An important study led by Portuguese conservation biologist Henrique Pereira and published earlier this year in Science conducted an extensive comparison of climate and biodiversity models. This analysis covered the period from 1900 to 2050, allowing for both historical and future-oriented exploration.
To simplify matters, the authors compared biodiversity impacts solely due to land use change (a predominant historical driver of biodiversity loss) with the combined impacts of land use change and climate change. The comparison included three different emissions and socioeconomic scenarios representing different storylines of global progress on sustainability and climate action. Unlike the Wiens and Zelinka review, this study looked across multiple aspects of biodiversity, not just the total number of different species. Other metrics of biodiversity included the intactness of habitat and the extent of habitat per species, offering a more multidimensional picture of biodiversity.
An initial encouraging insight from the Pereira et al. study is that declines in biodiversity from land use change alone may be expected to diminish, or even reverse, in the remaining first half of the century in response to land protection efforts assumed in the global sustainability scenario (see red bars Figure 2a). However, when climate change is added to the equation, all climate change scenarios continue to exacerbate biodiversity losses, with greater losses on higher emissions trajectories (see all color bars, Figure 2b).
Figure 2. Historical trends (1900 to 2015) and projections for each scenario to 2050 of different biodiversity metrics. Panel A (left) considers land-use change impacts alone, while Panel B (right) considers the combined impact of land use change and climate change impacts combined. Metrics correspond to relative changes per decade in global species richness (a), local species richness averaged across space (b), mean species global habitat extent (c), and local intactness averaged across space (d). Caption text and figure credit: Adapted from Pereira et al., 2024.
What we can also glean from this kind of analysis is how increasingly dependent society is on nature, not just for resource extraction but also for nature’s healthy functioning. In Figure 3, under all scenarios, models show increased human demand for material ecosystem services — the things we depend on practically from nature, like timber, food, and bioenergy (notably, bioenergy dependence greatly increases in the more global, sustainability-oriented scenario). By contrast, the functions nature relies on to provide those services (so-called “regulating ecosystem services”) are expected to decline in almost every area, including coastal resilience, a growing area of concern.
Figure 3. Historical (1900 to 2015) rate of changes in material and regulating ecosystem services at the global level and future projections for each scenario (2015 to 2050) from land use and climate change combined. Bars represent means across models, with values for each individual model also shown. Caption text and figure credit: Pereira et al., 2024.
Pereira et al.’s study helps to showcase how scientists and policymakers can draw upon existing modeling tools to better assess the impacts of climate change on biodiversity as well as the co-benefits (and tradeoffs) of pursuing solutions to both in tandem. The researchers’ results show the diminishing effects of land use change under the Global Sustainability scenario (see red bars in both Figures 2 and 3) and are encouraging in that sustainability policies aimed at a specific challenge, like land use conversion, can meaningfully impact that goal on a global scale, with co-benefits for climate. At the same time, the models show how sustainability pathways that include aggressive cuts to greenhouse gas emissions are necessary to stave off further impacts to biodiversity.
A glimmer of hope
As with mitigating climate change, reversing biodiversity loss is a daunting social task requiring well-designed policies, strong governance, and the more diffuse elements of social transformation, such as changes in norms, mindsets, and individual behavior. It’s easy to be discouraged that humans may fall short of achieving such a monumental undertaking. But what if lessons from human history show us the key to unlock our innate potential to rise to this challenge?
In a new perspective piece in Philosophical Transactions of the Royal Society B, ecologist and scholar of the Anthropocene Erle Ellis argues we underestimate the power of human aspirations to change how people relate to nature. As evidence, Ellis looks to humanity’s long history of dramatic interactions with nature, both for better and for worse. He cites examples from irrigation and granaries to the development of social norms to the more recent formation of environmental protection agencies and international environmental agreements.
For Ellis, the entry point to understanding how we can better relate to nature is recognizing these past examples where humans have devised and implemented transformational solutions to problems of our own making. “When these transformative capabilities to shape environments are coupled with sociocultural adaptations enabling societies to more effectively shape and live in transformed environments, the social–ecological scales and intensities of these transformations can accelerate,” Ellis wrote.
The underlying driver of successful transformation, for Ellis, is the power of culture and social learning, which in his view undergirds technological innovation (and adoption), good policy, and governance. Culture, then, becomes pivotal for progress at speed and scale.
Entry points
If Ellis is even partly correct about our latent potential, where are the most promising areas to focus attention? A team of scientists led by Brazilian ecologist Cássio Cardoso Pereira (2024) suggests six synergistic focus areas that would help to mitigate climate warming emissions while enhancing biodiversity.
- Conserve carbon stocks and sinks. Land and ocean systems have naturally sequestered over half of humans’ historical emissions. Priorities for protection are likely in the Amazon, Congo Basin, and Southeast Asia, which have high levels of carbon storage and biodiversity.
- Restore degraded lands. Marginal lands, or lands degraded from historical practices, can be repaired to enhance their carbon sequestration capacity. Designing restorations to repair ecosystem connectivity and cultivate rich, diverse native species can enhance biodiversity and associated ecosystem services.
- Integrate conservation with local fauna and flora. Ecosystems that help sequester carbon and provide resilience depend on healthy interactions between plants and animals. Thus, climate-oriented conservation strategies should take these interactions into account.
- Use only existing areas of agriculture, pasture, and silviculture. Although this area is in tension with other goals around livelihoods and food security, a direct path to avoiding additional emissions and biodiversity loss from land conversion is to establish strong policies that confine agriculture to already converted land.
- Incorporate biodiversity into business models. While many companies promote values and goals around the protection of nature and are increasingly attaching themselves to science-based targets for climate action, corporate plans tend to lack specificity about biodiversity. Corporations can reduce the net impact of their activities by quantifying the impact of corporate activities on biodiversity loss and committing to measurable and verifiable actions to mitigate those impacts.
- Convene joint biodiversity-climate COPs. Although both link to the pathbreaking 1992 Rio Conference on Sustainable Development, separate “Conference of Parties” currently address climate change and biodiversity issues on the international stage. Bringing these conversations together could further harness the synergies between them.
Such areas of attention require actionable science to inform good decisions where the details matter. One upcoming effort along these lines in North America is the Biodiversity and Climate Change Assessment. This report, with participation from Canada, the U.S., and Mexico, will be released sometime next year. Importantly, it will help to bridge communities of researchers who have previously contributed to either climate change-specific or biodiversity-specific assessment processes.
Ultimately, the systems that regulate both climate and life on Earth are deeply interwoven, and it’s impossible to consider the sustainability of either without looking at them together.
