Can we talk about climate change without considering biodiversity loss? The answer is complex, but from looking at these two crises as a whole, it’s unequivocal: no.

A 2019 synthesis review of many studies estimated that about 5% of species would be threatened with extinction if global warming were limited to 2 °C compared to the pre-industrial era (1850 – 1900). This figure rose to 16% should the temperature increase reach 4.3 °C. Remember that in 2024, the global average was already above 1.5 °C.

The decline in biodiversity also affects the climate: research shows that marine and terrestrial ecosystems sequester nearly 60% of the carbon that is emitted. That means that those losses amplify the greenhouse effect and contribute to global warming.

Biodiversity and ecosystems play key roles in the carbon cycle and water regulation, among other things. It is now well documented that climate change is one of the main drivers of biodiversity loss. Other factors also play a role, like habitat loss, pollution, invasive species and disease. 

These two major twenty-first century crises are interconnected, complex, and dangerous for ecosystems and human society.
 

Biodiversity in the face of global warming 

Quebec has been experiencing record-breaking temperatures in recent years: 2024 will be remembered as the province’s hottest year in 109 years. 

Rising temperatures, combined with changing rainfall patterns and extreme weather events, are altering the functioning and balance of ecosystems. 

But how does this happen? 

When healthy biodiversity regulates the climate

In general, the following premise applies: the more diverse an ecosystem is, the more resilient it is to climate disruption. 

This resistance is based in particular on the strength of interactions between plant, animal and microorganism species, as well as the connectivity of habitats. A healthy ecosystem has more species that can perform essential functions, like pollinating, maintaining soil vitality or water quality, and sequestering carbon.

When dysregulated biodiversity leads to a vicious circle

On the other hand, deforestation and forest fires reduce the carbon storage capacity of forests. Decaying biomass and smoke from wildfires release previously sequestered carbon into the atmosphere. 

Biodiversity loss also weakens the natural functions that limit the impacts of climate change at the local level. For example, reduced vegetation in urban areas, combined with impermeable surfaces such as asphalt, increases temperatures near the ground and accentuates heat islands. 

Vegetation loss also accelerates soil erosion. Without roots to stabilize it, land is more vulnerable to heavy rainfall, which further exposes natural environments and infrastructure located near water bodies.

Two inseparable crises

The scale of the upheavals already underway makes it essential to consider the climate and biodiversity crises as one and the same battle and to address them in a unified strategy.

Protecting ecosystems and increasing their resilience can reduce greenhouse gas emissions and help us adapt to the impacts of climate change and preserve the essential services nature provides, on which our societies depend. Conversely, mitigating global warming helps limit the pressure on species and habitats. 

The best way to address these two inseparable crises is to focus on nature-based solutions that are protected through consistent planning.

This planning can be guided by concepts like the Kunming-Montréal Global Biodiversity Framework, the objectives of which Quebec has committed to implement. Its targets include the restoration of 30% of degraded ecosystems; participatory, integrated, inclusive land use planning; and legal, administrative and policy measures to encourage companies to reduce their impacts on biodiversity.

But tackling this dual crisis requires more than a political commitment. We need concerted action by every decision-maker in society. By focusing on cooperation, knowledge sharing and innovation, we can turn these crises into catalysts for long-term change. The future depends on our ability to act together.