1386. The Need to Address the Dual Crises of Biodiversity Loss and Climate Change

The Amazon is one of the Earth's key climate stabilizers, and protecting the rainforest and its biodiversity is essential. An editorial published in BMJ argues that the dual threats of biodiversity loss and climate change have clear implications for human health and should be at the center of discussions at COP30.

Accelerating biodiversity loss around the world threatens climate stability, food security, and human health. Human pressures over the past century have driven biodiversity loss at rates 30 to 120 times faster than natural extinction rates. Since 1900, land-use change alone has led to a global species loss of approximately 2.3%. Model projections suggest that if land-use change and current rates of climate change continue in tandem, global biodiversity could decline by up to 5% per decade this century, with particularly severe losses expected in the tropics. At the same time, nature's ability to regulate critical ecosystem services such as pollination, water quality, and soil protection is declining. This decline is weakening nature's ability to manage and mitigate disease and health threats. For example, localized warming caused by deforestation has contributed to an estimated 28,000 excess heat-related deaths per year across the tropics since 2001.

Biodiversity loss and climate change are two sides of the same coin, each affecting the other. This is particularly true in countries like Brazil, where biodiversity is not only under severe threat but is also of global ecological importance. Over the past few decades, Amazon forest cover has declined by 20%, primarily due to land conversion to cattle pasture and soybean cultivation. An additional 17% of forests has been degraded by logging, fires, windstorms, and road construction, with degradation now accounting for approximately 73% of aboveground carbon loss, surpassing deforestation. Extreme climate events, such as severe droughts and floods, have also intensified, occurring more than twice as frequently as in the past century. Meanwhile, the Cerrado and other ecosystems continue to shrink due to agricultural expansion, mining, and urbanization. These changes threaten not only ecosystems but also human health. In Brazil, forest fires have been associated with a 38% increase in respiratory diseases, and land-use change has been linked to an increased risk of emerging zoonotic diseases.

What happens to Brazil's ecosystems has global implications. The Amazon is not only a cradle of biodiversity, but also one of the planet's major climate stabilizers and a "tipping point" for the Earth system. Unfortunately, warning signs are already emerging, with the southeastern Amazon becoming a net carbon source rather than a sink. Future projections estimate that by 2050, 10% to 47% of Amazon forests will be exposed to drought, fire, and fragmentation, potentially triggering rapid ecosystem transition. At the same time, declines in seed-dispersing species threaten forests' regeneration and carbon storage capacities, diminishing their role in climate change mitigation.

The Amazon is rich in biodiversity, but it is also home to diverse cultures, including 2.7 million indigenous peoples representing 350 ethnic groups. Indigenous peoples are among the most affected ecologically, socially, and culturally by biodiversity loss. However, these communities play a crucial role in protecting biodiversity and, ultimately, the global climate, by reducing deforestation, maintaining ecosystem services, and promoting the sustainable use of wild species. Their knowledge contributes to agroforestry, local conservation strategies, and ecosystem restoration, and serves as a model for sustainable land governance. Between 1981 and 2010, more than 50% of new compounds approved as medicines were naturally derived or inspired, primarily from plants.

We hope that COP30 will deliver more than just declarations. Governments must commit to protecting and enhancing biodiversity as a solution to climate stabilization. Resilience to climate change depends on nature, and both nature and local communities are essential to the health of communities around the world. Degradation of the biosphere puts both at risk.

(Reference)
Opinion. The Amazon is one of Earth’s major climate stabilizers—we must protect the rainforest and its biodiversity. BMJ 2025; 391 doi: https://doi.org/10.1136/bmj.r2186

Contributor: IIYAMA Miyuki, Information Program