Rewilding animals is one of our best options to partner with nature to combat climate change

Mar 27, 2023

Magnus Sylvén & Oswald Schmitz

Exactly one week ago the Intergovernmental Panel on Climate Change (IPCC) released its latest report on the current and future state of the Earth’s climate. The report had a rather dire message: we are unlikely to achieve the goals of the Paris Climate Agreement of cutting in half greenhouse gas emissions from all sectors by 2030, leave alone reaching net zero emissions by 2050. This failure means that we are headed toward surpassing a global mean temperature rise of 1.5ºC and facing a hotter, drier and stormier world. But the report tempers that message by stating that it is not too late. If we act now, and act fast, we can still change course.

Acting now and fast means reducing annual emissions by billions of tonnes of CO2-eq (GtCO2-eq) between now and mid-century. IPCC’s top 5 options for reducing net emission expeditiously and the amounts of reductions they buy us are (in order of importance): (1) rapid transitioning to solar energy generation (4.5 GtCO2-eq/yr); (2) reducing the conversion of natural ecosystems (4.0 GtCO2-eq/yr); (3) rapid transitioning to wind energy generation (3.9 GtCO2-eq/yr); (4) enhancing carbon capture and storage in agriculture (3.5 GtCO2-eq/yr); and (5) restoring, afforesting and reforesting ecosystems (2.8 GtCO2-eq/yr). We should also look for “comprehensive, effective, and innovative responses” that “can harness synergies and reduce trade-offs between adaptation and mitigation”.

The report further acknowledges the importance of simultaneously maintaining the adaptability and resilience of nature’s species and ecosystem functions and services by ensuring “effective and equitable conservation of approximately 30% to 50% of Earth’s land, freshwater and ocean areas”. The need to safeguard nature as part of climate action is certainly needed to sustain society into the future. But we can do even better by enlisting nature to help us mitigate climate change more quickly.

Today, one week later, on March the 27th we, along with 13 other colleagues, announce the release of a report describing a new way to enlist nature to help us mitigate climate change. The article, entitled “Trophic rewilding can expand natural climate solutions”, published in the journal Nature Climate Change describes how rewilding (protecting and enhancing) populations of key wildlife species across the world could further reduce emissions by billions of tonnes annually. And the amount of reduction rivals each of the IPCC top 5.

Mesopelagic fish

Each year mesopelagic fish living in the twilight zone in our ocean facilitates the capture of twice the amount of CO2 emitted by the EU-27 through fossil fuel burning. Image credit: Danté Fenolio

Rewilding animal populations to enhance natural carbon capture and storage is known as “Animating the carbon cycle” (ACC). We make the case that it is probably among the best nature-based climate solution available to mankind. This is because, as we show, wild animal populations play critical roles in controlling the carbon cycle in terrestrial, freshwater, and marine ecosystems through a wide range of processes. We present data showing that protecting or restoring populations of nine wildlife species (or groups of species) – marine fish, whales, sharks, grey wolf, wildebeest, sea otter, musk ox, African forest elephants, and American bison – could collectively facilitate the additional capture of 6.4 billion tons of carbon dioxide (GtCO2) annually. This is more than 95% of the amount needed every year (6.5 GtCO2) to meet the global target of removing 500 GtCO2 from the atmosphere by 2100, which would keep global warming below the 1.5ºC threshold.

Our article outlines the value to climate mitigation not only for protecting the functioning of wild nature we have left, but enabling degraded ecosystems to return to full health through trophic rewilding at scale. And, with the right enabling conditions, evidence show that this can be done within the urgent timeline set by the IPCC. There is potential to do even more when considering the potential of many other candidate wildlife species identified in our article.

What is the significance of these findings in the context of this latest IPCC report? Here are some initial conclusions:

  • The ACC perspective, and how wildlife species could significantly enhance carbon sinks across ecosystems, is not at all considered by the IPCC.
  • The potential capture and storage of 6.4 GtCO2 annually that comes from protecting and restoring populations of nine species/species groups is comparable to the potential emissions reductions from solar, wind, and carbon sequestration in agriculture.
  • Implementing an ACC approach along with IPCC’s ecosystem protection and restoration measures could double the emissions reduction mentioned in the ICPP report (2.8-4.0 GtCO2-eq/yr).
  • Marine fish, in particular, play a very significant role in facilitating the capture and storage of 5.5 GtCO2/yr. The importance of seriously considering this neglected part of the carbon cycle speaks for itself. We need to look beyond the IPCC conclusion that simply “rebuilding overexploited or depleted fisheries reduces negative climate change impacts on fisheries”. Global fisheries management must take urgent responsibility to avoid negatively impacting the climate and the overall functioning and diversity of the ocean by rebuilding depleted fish stocks and implementing large no-take fishing zones both in territorial and High Seas waters.
  • With its holistic ecosystem-based, functional biodiversity approach, ACC through rewilding is a prime example of how to achieve synergy between climate mitigation and adaptation, and biodiversity conservation.

The time has come to embrace a holistic, integrated, and functional systems perspective that explicitly includes biodiversity—especially animal diversity— and the interlinkages with ecosystem carbon cycling and climate change. The sustainability of the planet, more than ever, depends on such integration. The recent commitments to protect 30% of both land and sea (including High Seas) by 2030 can serve as a key basis for implementing ACC at ecologically relevant spatial scales. Including ACC as a nature-based climate solution could help humanity meet the target of halving its GHG emissions by 2030. We therefore call for the restoration of wildlife populations to be included in the scope of nature-based climate solutions – solutions which help nature to lock up carbon and adapt to climate change.

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