Opportunities to address both climate change and the extinction crisis are time-bound. It has become clear that beyond 1.5⁰C average rise in global temperature, the biology of the planet becomes gravely threatened as ecosystems literally begin to unravel. Similarly, if current land conversion rates, poaching of large animals, and other threats are not dramatically slowed or halted in the next ten years, a ‘point of no return’ could be reached for multiple ecosystems and species. While there are several proposed pathways to mitigating climate change, including uncertain technologies that could remove carbon from the air, we know that natural ecosystems are key to maintaining the abundance and diversity of life on Earth as well as human prosperity in a warming world.
Carbon-rich ecosystems, by definition, sequester (both store and pump) the most carbon from the atmosphere. This carbon sequestration service is key to climate stabilization and to climate change mitigation. It is no coincidence that some of the most carbon-rich ecosystems on land -- natural forests -- also harbor high levels of biodiversity. Evolution has generated carbon-rich forests by packing in long-lived trees that also feed stable soil carbon storage pools. This effect is made possible by high levels of co-existence among diverse species and growth forms, and this co-existence has been made possible by the biotic interactions that generate competition and defense.
Try to imagine a tropical forest without pests, pathogens, pollinators, decomposers, or predators. You likely can’t. That’s because their interactions with primary producers (the plants) are what generates the carbon rich growth forms that take the carbon out of the atmosphere and store it in the soil and woody biomass. In the words of the Heinz Award winning climate and biodiversity scientist, and co-author of the GDN, Greg Asner, “It is not Gaia or herbal massage; it is chemistry and physics.” These carbon sequestration and storage benefits extend far beyond tropical rainforests into other biomes -- peatlands, tundra, mangroves, ancient grasslands, wetlands and the marine realm. All of these ecosystems conserve distinct assemblages of plants and animals and have a role to play in balancing the global climate system.
It is based on this co-dependence of biodiversity and climate mitigation that the paper, “A Global Deal for Nature (GDN): Guiding Principles, Milestones, and Targets” proposes a bold vision for what we need to do to ensure the functioning of the biosphere, especially as the world is stressed from increased global temperatures. The GDN is based on scientific guidelines that could interlink two different United Nations conventions – the Framework Convention on Climate Change (aka the Paris Agreement) and the Convention on Biological Diversity – making them mutually reinforcing. We emphasize three themes that taken together can save life on Earth: mitigating climate change, protecting biodiversity, and reducing threats to ecosystem intactness and species survival.
First, the paper makes a strong connection between climate change and biodiversity loss. Recent literature, compiled in the new book Biodiversity and Climate Change (Lovejoy & Hannah, ed.) shows that anything above 1.5˚C in global average temperature rise would mean the loss of species on such a scale as to be potentially irreversible. Thus, if we aren’t able to solve the climate crisis, we will not be able to solve the biodiversity crisis. Conversely, if we aren’t able to cease the destruction of forests and other habitats, we will likely be unable to stay below the threshold on 1.5˚C. Here’s why…
Approximately half of Earth’s terrestrial surface is currently in a natural condition and capable of supporting functioning ecosystems. A new climate model published by Springer Nature in early 2019, Achieving the Paris Climate Agreement Goals, shows that we can only meet the target of remaining below 1.5°C in average global temperature rise by ending the conversion of forests and other natural lands by 2030, effectively placing half of the Earth’s lands under protection. This major conservation effort would need to be coupled with a forest restoration effort and other natural climate solutions to draw down carbon from the atmosphere (providing ‘negative emissions’) alongside a rapid transition to carbon-free energy, like wind and solar power, by 2050 (see Fig 1).
How does this translate to conservation targets? The GDN aims to highlight a new era of ambitious conservation in which international institutions, governments and people are working together to save nature -- from supporting communal conservancies in Namibia’s Damaraland refuge for lions and elephants, to indigenous communities in the Peruvian Amazon that conserve key ecosystems and safe havens for jaguars and rare primates, to the last home of the orangutan in indigenous reserves in Borneo, as well as incentives for governments to legally protect intact boreal forests across Canada, Russia, and northern Europe that are home to so many breeding songbird populations.
Because protection will be phased in over time, and because life on Earth is distributed unevenly, it’s crucial that biologically important areas are protected first, and that protection is done in a representative matter. The paper demonstrates how expanding PAs to meet the 30% by 2030 milestone could improve representation, and the terrestrial areas of the Earth that have already met this target.
Besides representation, the paper highlight groups of high-priority natural sites and species that should be targeted within ecoregions. Milestone of a GDN implemented by 2030 would include protecting all 600 sites containing the world’s last homes of endangered species per Alliance for Zero Extinction Sites (AZEs), 90% of Key Biodiversity Areas (KBAs), 80% of extant primary habitats from 2018 baseline, and doubling of at least 10 key populations of the world’s megafauna (see below table for examples of proposed features). Protecting areas with key populations of extant large mammals can also help protect the world’s terrestrial carbon storehouses:
While there are clearly many ways to get to the goal of protecting half the Earth, the GDN paper champions a pathway that prioritizes representation of biodiversity for vertebrate, invertebrate, and plant species. Many analyses show how an extinction crisis can be averted by protecting the most important sites between now and 2030 as part of the 30% protected target, focusing not just on large, intact areas, but also small habitat patches that are essential for the survival of species, as well as the provisioning of ecosystem services such as pollination. A first-ever analysis of the overlaps between many different conservation priorities was published in the paper (see Fig 4):
For the marine realm, the GDN calls for closing enormous gaps in marine conservation: studies show that 35-50% of the ocean must be protected to meet biodiversity protection and sustainability goals, yet only 2% of the world’s ocean is currently in fully to high protected marine reserves. Our recommendations for expanding this system include both addressing representation, but also providing full protection of all critical habitats for threatened species, as well as critical migratory corridors for endangered species of fish, marine mammals, and sea turtles (see Fig 5).
The success of a GDN will depend not only on expanded area-based protection measures, but also on ensuring policies are in place to reduce threats and drivers of habitat and species loss. Moving agricultural expansion to degraded areas; careful oversight and planning to avoid harmful impacts of transportation expansion projects; and banning the international transport for commercial purposes of all threatened wildlife and plant species should be in place by 2050. Support will be needed to enable titling and management of indigenous lands as part of the global reserve system, to national governments seeking to protect intact habitats under climate stabilization areas, and to identify, conserve, and protect fragments of habitat that may be embedded in working landscapes – yet are essential to ecosystem services and biodiversity conservation.
Earth’s bounty underpins human well-being, and yet we are poised to wipe these out in the blink of an eye in geological time. Now it is time to give back before our living standards and spirits are further diminished by the loss of the diversity around us. With recent advances in technology and globally available earth information systems, we have the tools necessary to protect most of life on Earth and monitor our progress, should we organize and choose to do so.
Creating a Global Deal for Nature would allow humanity to develop a vibrant low-impact economy while leaving room for the rest of life on Earth, becoming the overarching conservation paradigm for this century. Together, the Global Deal for Nature and Paris Climate Agreement will foster nature and humanity’s health and a future for all species and future generations.