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Cascading Change: The Urgent Need to Tackle Biodiversity Loss and Climate Change Together BY DAVID DUTHIE, BES-NET SENIOR KNOWLEDGE MANAGEMENT CONSULTANT

In December 2021, people the world over were moved by an aerial photo of six giraffes, emaciated by a long drought in northern Kenya, lying dead on dry earth. Taken a month after the close of the UN Climate Change Conference (COP26), this photo compellingly illustrated the inextricable link between the unfolding climate catastrophe and the loss of biodiversity. These two crises are mutually reinforcing in complex ways.

This article addresses how they affect each other and underscores the need to invest in transformative win-win-win solutions. Part 2 of this series explores the nature of environmental tipping points and the opportunities they present.

Trajectories of the existential challenge

The climate-biodiversity dual crisis underscores a conundrum — how to sustain an exponentially growing human enterprise on a finite planet. There are four potential resolutions of this problem:

  1. We expand the human enterprise beyond this planet.
  2. We remain a one-planet species but develop the technology to decouple a growing economy from environmental harm.
  3. We sustain (and potentially enhance) human well-being within a steady-state economy.
  4. We permit civilization to collapse, thus reducing human resource consumption and environmental destruction.

Because each path has its advocates, humanity appears to be following all of them simultaneously. Our response to the climate and biodiversity emergencies will help determine which trajectory becomes dominant.

In 2021, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and the Intergovernmental Panel on Climate Change (IPCC) jointly released the Biodiversity and Climate Change Workshop Report, which consolidates dialogue and research on these two crises. The report provides guidance as we embark on another year of reaffirming global commitment and action.

The United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD) share a common origin in the 1992 Earth Summit. However, for much of the succeeding 20 years, each convention progressed in relative isolation from the other despite growing evidence of strong interactions between biodiversity and climate change[1].

The steady escalation of these crises spotlights the necessity of examining these interactions, both as drivers of negative change and as potential contributors to solutions. Modern human actions have altered the climate and reduced biodiversity to levels that increasingly threaten the stability of human societies, making mitigation and adaptation measures urgent matters of self-interest.

The Earth’s climate has varied enormously over millions of years, causing five major extinction events. Modern agricultural human societies have emerged and developed over the past 10,000 years — an era that falls within the Holocene, a period of relative climatic stability. Anthropogenic climate change has upended that stability, posing a threat to all species. In our interconnected economic system, any localized societal breakdown can cause worldwide stress. Limiting climate change and biodiversity loss mitigates this risk, improving our ability to adapt to coming changes.

IPBES-IPCC report spells out drivers of twin disasters

The IPBES-IPCC report organizes and assesses the complex relationships among humanity, climate change and biodiversity in a readily comprehensible framework (see below).

Historically, the four major drivers of biodiversity loss have been habitat loss (land-use change), over-exploitation, invasive species and pollution. In recent centuries, climate change has become another powerful driver of biodiversity loss, although it could also be considered an amplifier of the other four drivers.

The figure below presents this framework in a different context, showing the interrelationships of the indirect and direct drivers of climate change and biodiversity loss, both of which dramatically affect human quality of life.

Scientists have long known that climate change would have a profoundly negative impact on biodiversity conservation. Research conducted in recent decades has confirmed that negative impact are occurring, not only in protected areas but almost everywhere on the planet[2].

Not much is known about the potential ability of ecological communities to adapt to climate change. Species respond to climate change in different ways and at different rates, disrupting interactions such as pollination and seed dispersal etc. in complex ways. These disruptions will likely lead to the creation of novel ecosystems — environments not previously documented on Earth[3]. Such changes could have both positive and negative consequences for nature’s contributions to humanity.

How climate change affects biodiversity

Different species adapt to climate change through behavioural changes, physiological adaptations, range shifts and evolutionary change[4]. A few species, especially those with rapid life cycles, have already demonstrated some capacity for physiological, behavioural and genetic adaptation[5]. However, most species’ adaptational capacities and limits are not yet well known.

Climate change has a global impact; it affects nearly all species. For example, each species thrives within a thermal range and has a thermal optimum. Before the vast expansion of the human population in recent centuries, the global climate changed tremendously but slowly, enabling species to track their thermal niches in space and time, often over long distances[6].

As global temperatures rapidly rise, species must track their niches much more quickly and in an increasingly crowded world in which habitat loss, land-use change and man-made infrastructure inhibit movement. On land, species track their thermal niches in three main ways: moving towards the poles, moving to higher altitudes or altering the annual cycles during which they inhabit ecosystems[7].

Thermal niche tracking is, for most species, best thought of as a multi-generational adaptation, especially for sessile species such as plants and coral reef species. This is with the exception of larger vertebrates and birds. Barriers to species movement are less severe in the marine environment and there is already clear evidence that species are on the move[8]. This is already having far-reaching impacts on both biodiversity and human societies that depend upon marine resources[9].

Species range shifts alter population densities, leading to changing patterns of species richness. Often, the very species we are trying to conserve in protected areas are forced to move beyond boundaries[10]. Other effects of global warming — including sea-ice loss, sea-level rise, ocean acidification and more frequent and more severe storms, droughts, floods, heatwaves and wildfires — also affect biodiversity, often sequentially or simultaneously, often amplifying impacts.

Climate change mitigation and biodiversity conservation

Nature plays a critical role in sustaining the planetary carbon cycle. The oscillations of the Keeling Curve, which tracks seasonal dips amid the overall steady rise in atmospheric carbon dioxide, show how photosynthesis and respiration drive the cycle[11]. Land and ocean carbon sinks absorb about 50% of annual anthropogenic CO² emissions[12], but carbon acidifies the ocean, causing a grave threat to biodiversity.

Climate change mitigation encompasses maintaining, restoring and enhancing these sinks as well as ensuring long-term carbon storage in biomass, soils and sediment[13,14]. All measures to reduce deforestation and forest degradation are considered as climate mitigation measures – clear examples of potential “win-win-win” measures when the rights of indigenous peoples and local communities are respected at the same time[15].

Project Drawdown[16] assesses the potential contributions of some 80 climate change mitigation measures, 20 of which could enhance biodiversity conservation. Most of these measures would be considered nature-based solutions (NbS) to climate change[17], yet even these could, if poorly implemented, harm biodiversity.

The project proposes four guidelines to guard against this:

  1. NbS are not a substitute for the rapid phase-out of fossil fuels.
  2. NbS can involve a wide range of land and marine ecosystems, not just forests.
  3. NbS should be implemented with the full engagement and consent of indigenous peoples and local communities in a way that respects their cultural and environmental rights.
  4. NbS should be designed to provide measurable benefits for biodiversity[18].

Most actual or proposed climate change mitigation measures can potentially harm biodiversity, especially when poorly implemented on a large scale. Potential risky measures include hydropower plants, wind farms and bioenergy with carbon capture and storage operations. All of the IPCC models for holding temperature rise to 2°C by the end of the century[19] include extensive use of all these measures.

Any measure that slows climate change or reduces non-climate stressors on species and ecosystems can assist biodiversity adaptation. One significant example of alleviating a non-climate stressor is the reduction of agricultural and mining pollution into the Coral Sea, habitat of the Great Barrier Reef[20]. Another, almost desperate measure being tried in the Reef is cloud-brightening — spraying seawater into the air above the reef to whiten low clouds, making them reflect sunlight into space and away from the reef[21].

Win-win-win solutions for biodiversity, climate change and society

As noted above, the Earth’s land and oceans absorb more than 50% of anthropogenic CO² emissions. The land absorbs CO² through forest regrowth and enhanced photosynthetic CO² uptake (CO² fertilization) of terrestrial vegetation[22]. Oceanic uptake is due to CO² solubility in the ocean and the organic carbon cycle that is driven by planktonic photosynthesis, carbon sequestration in coastal vegetated habitats and the biological pump that moves carbon from the upper ocean layers to the deep ocean waters and ocean floor sediments. Most of this uptake occurs in natural and semi-natural ecosystems with significant biodiversity.

A recent report[23] by the UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) spotlights strong synergies between carbon stocks and high-biodiversity areas to be prioritized for conservation. Increasing high-biodiversity areas to 30% of land globally could safeguard more than 500 gigatons of carbon (GtC). When prioritizing areas for conservation management, taking both biodiversity richness and carbon stock into consideration can secure 95% of the biodiversity benefits and nearly 80% of the carbon stock benefits that could be obtained by prioritizing based on either value alone.

Protected terrestrial areas store approximately 238 GtC (12% of land carbon stocks) and sequester 0.5 GtC yr-1, or 20% of all terrestrial carbon stocks[24]. Protected areas are a negligible source of carbon export to the atmosphere. For example, 2,018 protected areas from tropical countries store a total of 35.8∓ 15.7 GtC (14.5% of total carbon biomass estimated in tropical countries), with a mean loss of 38∓17 MtC yr-1[25]. To reverse biodiversity loss and enhance climate change mitigation, an estimated 30.6% of unprotected land surface (41 million km2) must be added to the existing protected area estate, preventing the loss of 1.49 GtC of carbon as well as a loss of biodiversity if these areas are extensively degraded[26].

To reverse biodiversity loss and enhance climate change mitigation, an estimated 30.6% of unprotected land surface (41 million km2) must be added to the existing protected area estate.

Interestingly, 92% of the area needing protection for carbon storage and drawdown is covered by the area needed to reverse biodiversity loss[27]. If we limit global warming to 2°C and conserve 30% of the terrestrial surface, we will more than halve aggregate extinction risk relative to a base case of unmitigated climate change and no increase in conserved areas[28]. These studies demonstrate the strong interlinkages between biodiversity conservation and climate change mitigation.

Most of the 20 action-oriented targets for 2030 proposed in the first draft of the post-2020 Global Biodiversity Framework[29] have direct or indirect impacts on climate change mitigation even though they were not primarily designed with this intention. NbS that include actions to halt or reverse biodiversity loss will enhance sequestration of anthropogenic CO² on land and in the oceans. Likewise, actions that reduce greenhouse gas fluxes to the atmosphere from wildfires, land cover change and agricultural practices increase the reflectivity of the land surface (albedo change), likely reducing biodiversity loss and mitigating climate change.

Reducing deforestation is a clear example of a “win-win-win” policy intervention that generates positive outcomes for biodiversity and reduces the risk of human exposure to zoonotic diseases while maintaining carbon stocks, contributing to carbon sequestration and storage, and leading to positive human health benefits both locally and globally[30].

A second “win-win-win” example is involving indigenous peoples in community conservation areas. These areas, natural or modified ecosystems containing significant biodiversity and ecological services, are voluntarily conserved through customary laws or other means. While the principal intention may be to support indigenous livelihoods and well-being as well as cultural and spiritual values, these conservation areas protect biodiversity and ecosystem services and bring associated benefits, including those related to climate change mitigation[31].

Investing in piloting and scaling up NbS can play a crucial role in achieving transformative change by emphasizing nature’s values, recognizing diverse knowledge types and providing opportunities for community engagement and improved ecosystem management[32]. Emerging from the discussions at COP26, the Glasgow Climate Pact recognizes these transformative solutions, calling for the protection, conservation and restoration of nature, including both terrestrial and marine ecosystems, to achieve long-term climate action goals.

This silver lining was marked by 45 governments that committed to ramping up conservation efforts and prioritizing responsible farming. The Government of Canada led by committing CAD 1 billion, a fifth of its climate finance budget, to NbS[33]. In 2022, as countries move towards the fifth session of the UN Environment Assembly (UNEA-5) and the 15th meeting of the Conference of Parties to the UN Convention on Biological Diversity (UN CBD COP15), one question will be top of mind: can these commitments for nature be turned into action before it’s too late?

Part 2 of this article will spell out the need to jointly consider biodiversity, climate and the social dimensions of systems to identify risks of crossing critical thresholds. Read it here.

Read part 2 here

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David Duthie is an environmental biologist with a doctorate in migration of insects. After a career as a tutor and environmental consultant, he joined UNEP in 2000 in the GEF Division and then the Secretariat of the Convention on Biological Diversity before retiring to Oxford, United Kingdom, in 2016.

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Image by geralt on Pixabay Image by dassel on Pixabay Image by marcinjozwiak on Pixabay Image by geralt on Pixabay