Efforts to address climate change and the erosion of biodiversity are often conducted separately. Yet they are inseparable because terrestrial and marine ecosystems shape and depend on the climate. As we head into 2020, when the international political agenda will focus on biodiversity conservation, we must remember that ecosystems are an essential component of the response to climate change.
Ecosystems are deteriorating all over the world
This is one of the most alarming messages in the IPBES report. According to its authors, the planet is on the verge of the sixth mass extinction, the first caused by humans.
Scientists say, “we are eroding the very foundations of our economies, livelihoods, food security, health, and quality of life worldwide.” They also add, “it is not too late to make a difference, but only if we start now at every level, from local to global.”
The main pressures ecosystems face come from economic activities, the expansion of cropland and pastures, unsustainable agricultural and forestry practices, urban sprawl, and the development of infrastructure and resource extraction. All of these activities degrade land and biodiversity directly.
Climate change is an additional contributor to this deterioration
Due to a two-fold increase in greenhouse gas emissions, the rise in average worldwide temperatures by at least 0.7°C since 1980 is wreaking havoc on ecosystems: disruption of growing seasons, changes in species ranges, loss of species and natural habitats, acidification of the ocean and coral bleaching, loss of genetic diversity, and so on.
According to a WWF study, even if we manage to fulfill the 2015 Paris Climate Agreement commitments by keeping average temperatures below 2°C, massive biodiversity loss will still occur. 25% of plant and animal species may disappear in the areas with the highest levels of biodiversity. This figure could reach nearly 50% if the climate warms by 4.5°C. This is because these species will be unable to adapt quickly enough to changing climatic conditions and migrate to more suitable habitats in time. They will also face a lack of resources.
Part of the solution is maintaining functional ecosystems
Beyond the massive “biological” loss, ecosystem deterioration leads to:
- an increase in greenhouse gas emissions and a reduction in the carbon sequestration capacity of the biosphere (ocean, soils, and forests), thus accentuating global warming;
- an increase in the impact of extreme weather events such as floods, droughts, heatwaves, and storms.
Source: IUCN, 2019, “Nature-based Solutions for Climate Change Adaptation & Disaster Risk Reduction“
This is a veritable vicious circle. But if we examine the problem from a different angle, the way we manage ecosystems—especially in marine, agricultural, and forest environments—can either amplify or mitigate global warming and its impacts.
Protecting these ecosystems is therefore an important part of the solution to climate change. According to IPBES, ecosystems (oceans, soils, and forests) currently absorb 30% of greenhouse gas emissions.
They also play a protective role by acting as a local climate buffer by reducing the impact of extreme weather events such as storms, droughts, and rising sea levels. And they provide essential services that help humans adapt: they regulate air and water quality and soil fertility, help with disease control, and so on.
Multi-service ecosystems need protection
If we look at coastal wetlands, mangroves, marshes, and coastal seagrass all store the equivalent of 200 million tons of carbon per year. This is equivalent to the emissions of 150 million cars. Photosynthesis produces plant matter from the sun’s energy and the CO2 in the atmosphere. This plant matter (roots, leaves, branches, etc.) then decomposes into the soil as carbon-rich organic matter.
These ecosystems also provide many services. They limit the power of waves and thus coastal erosion, which is often aggravated by climate change. They help purify water by acting as a filter and serve as a nursery for juvenile species since predators can’t follow them into the roots of mangroves. And they provide building materials, food and even medicines to local populations.
Yet human activities often destroy or degrade these ecosystems through the creation of agricultural areas, construction of hotels, pollution, etc. This degradation inhibits the carbon pump action needed to remove some of these greenhouse gases from the atmosphere. It may even occasionally release carbon stored in the soil and vegetation. As a result, these ecosystems can no longer protect the coastline and offer other ecosystem services.
Three levels of response to the climate challenge
By combining the recommendations of the IPCC and the IUCN (International Union for Conservation of Nature), we can identify three levels of ecosystem-based responses to climate change, also called “nature-based solutions”:
- protect ecosystems that are functional and in good ecological condition;
- sustainably manage ecosystems used for human activities (agriculture, fishing, land-use planning, etc.);
- restore degraded ecosystems.
In any case, limiting the average temperature increase to 2°C by 2100 is critical to protecting the biosphere. The effectiveness of these nature-based solutions greatly depends on our ability to limit global warming: the greater the impacts of climate change, the less likely ecosystems will be able to adapt and fulfill their climate regulation and protection functions.
It cannot be said enough: urgent action is necessary to limit greenhouse gas emissions. But the sustainable use of natural resources is also essential.
The international agendas on climate and biodiversity will converge in 2020, with the IUCN Congress, the COP15 conference on biodiversity in Kunming (China), and the COP26 climate conference at the end of the year. These key political events will offer the international community opportunities to make new and ambitious commitments on these two issues, which are inextricably linked.
The opinions expressed on this website are those of the authors and do not necessarily reflect the official position of their institutions or of AFD.