Science

Science

A ‘GLOBAL SAFETY NET’ TO REVERSE BIODIVERSITY LOSS AND STABILIZE THE EARTH’S CLIMATE

Read the full paper in Science Advances. Download the GIS layer files


ABSTRACT
Global strategies to halt the dual crises of biodiversity loss and climate change are often formulated separately, even though they are interdependent and risk failure if pursued in isolation. The ‘Global Safety Net’ maps how expanded nature conservation addresses both overarching threats. We identify 50% of the terrestrial realm that, if conserved, would reverse further biodiversity loss, prevent CO2 emissions from land conversion, and enhance natural carbon removal. This framework shows that, beyond the 15.1% land area currently protected, 35.3% of land area is needed to conserve additional sites of particular importance for biodiversity and stabilize the climate. Fifty ecoregions and 20 countries contribute disproportionately to proposed targets. Indigenous lands overlap extensively with the Global Safety Net. Conserving the Global Safety Net could support public health by reducing the potential for zoonotic diseases like COVID-19 from emerging in the future.

INTRODUCTION
Approximately half of Earth’s terrestrial surface is considered to be in a natural or seminatural condition. How does this remaining habitat overlap with global conservation priorities and carbon storage requirements? This paper highlights sites of particular importance for biodiversity where additional conservation attention is needed, and additional intact lands of particular importance for carbon storage and other ecosystem services. It also depicts the coincidence and disparities between terrestrial biodiversity and carbon storage priorities. This spatially explicit output documented in “A Global Safety Net” is intended to be a dynamic tool to support multilateral, national, and subnational land use planning efforts.

While the parallel crises of biodiversity loss and climate change have generally been approached separately, a key solution for two of the most pressing challenges of our time is the same: conserve enough nature and in the right places. Analyses designed to protect biological diversity have converged on the need to conserve and connect approximately half the Earth. In addition, several studies indicate that above 1.5°C in global average temperature rise, many ecosystems would be unable to adapt and, with increased biodiversity loss, could collapse. Nature-based solutions offer essential means to achieving the global climate objective of staying below 1.5°C. Achieving a future in which people and nature thrive is possible, but more ambitious conservation targets will be required.

The need for an ambitious global conservation agenda has taken on a new urgency in 2020 after the rapid spread of the COVID-19 virus. Global shifts in mammalian population trends reveal key predictors of virus spillover risk. Extensive deforestation in the tropics has led to humans coming into greater direct contact with vector-borne pathogens (e.g., Zika virus, which emerged from mosquito carriers in the Lake Victoria Basin forest-savanna) or via mammalian carriers that serve as viral hosts (e.g., HIV virus, which emerged from primates in the Northeast Congolian lowland forests). As important, achieving the area-based targets to protect all remaining intact and semi-intact terrestrial habitats would be an effective solution to reduce contact zones, helping to limit the chance of zoonotic diseases from affecting human populations in the future.

Here we examine where conservation of the terrestrial realm could be scaled to support biodiversity by securing additional lands to improve the resilience of ecosystems and secure terrestrial carbon stocks, both of which are essential if we are to have a chance of achieving the 1.5°C goal. The Global Safety Net explicitly avoids areas of concentrated human settlement, but it does not exclude resident human populations at relatively low densities in remote areas. We view this as a positive because, in particular, the sustained presence of indigenous communities within intact areas can have long-term benefits for both biodiversity and carbon storage.

This initial version of the Global Safety Net includes 11 spatial layers that, when combined, address expanded biodiversity protection and climate stabilization for the terrestrial realm. We also scope out a preliminary system of wildlife and climate corridors to identify the approximate amount of land that would be required to connect protected areas and intact landscapes. Besides mapping and assessing remaining natural habitat, we present a table of optimized contributions by ecoregion and by country required to maximize both biodiversity outcomes and land-based carbon storage. We also show how these targets may overlap with indigenous lands.

One potential application of the Global Safety Net is to inform the development of “common but differentiated” targets under the new post-2020 framework of the Convention on Biological Diversity. It could also help guide land-based mitigation in Nationally Determined Contributions (NDCs) made under the United Nations Framework Convention on Climate Change. The digital map of the Global Safety Net can be disaggregated by country, ecoregion, and indigenous territory, to shed light on overarching questions:

How much does an ecoregion or country contribute to meeting global biodiversity targets? Do ecoregions identified as priorities for biodiversity protection also contribute disproportionately to carbon storage? What is the potential role of indigenous peoples’ lands in supporting bio- diversity protection and climate stabilization? Which ecoregions and countries will require the greatest investment in connectivity? At a local scale, the Global Safety Net can serve as a framework to align subnational land use planning efforts with global conservation and climate targets. The reverse is also imperative, as regional conservation planning efforts can replace various parts of the global layers where they are available.

Authors: Eric Dinerstein, Anup Joshi, Carly Vynne, Andy Lee, Félix Pharand-Deschênes, Manno Andrade França, Sanjiv Fernando, Tanya Birch, Karl Burkart, Gregory Asner, David Olson.

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