Written by Anita Lazurko and Joanna Raymond
2023 has so far been a year dominated by new climate records and extreme weather events such as extreme heat in southern Europe, flash floods in Hong Kong, Slovenia and Brazil, and the highest recorded global monthly average sea surface temperature in August (WMO, 2023). The list goes on.
The soaring temperatures and dry weather have contributed to catastrophic wildfires on multiple continents. An estimated 2.2 million hectares of land burned during the wildfires in Canada this summer and, to make matters worse, provinces such as British Columbia are now bracing for a major drought just as the wildfire season comes to an end (Cecco, 2023). By the 26th August 2023, cumulative CO2 emissions from the devastating Greek wildfires were nearing 8 million tonnes, already over double the 2003-2022 average. By 29th August, the fires had destroyed an area bigger than New York City (Olorenshaw et al., 2023; Prousalis and Tagaris 2023). The world is now warming faster than any point on record and the impacts on people, biodiversity and the planet are now being felt.
The causes of climate change are well understood. Still, concentrations of carbon dioxide reached record values this year, of 425.01ppm on 28th April 2023 NASA Mauna Loa observatory in Hawaii, which means 50 percent more than pre-industrial levels (i.e. before 1750). These gases are trapping increasing amounts of the sun’s heat in the Earth’s atmosphere, causing global temperatures to rise and the climate to change, with increasing extreme weather events and associated impacts, such as more flash flooding and intense wildfires (Di Virgillio et al., 2019).
But what does the rapidly changing climate and associated increase in extreme weather events mean for biodiversity? And to what extent is climate change a driver of the declining global trend in biodiversity (Pascual et al., 2021)? What role can biodiversity play in both climate change mitigation and adaptation?
The importance of biodiversity and its connection to climate change
Answering these questions first requires an understanding of what we mean by biodiversity and why it is so important. Biodiversity is essential for healthy ecosystems, for the processes supporting life on Earth, for providing the food we eat, oxygenating the atmosphere, regulating the water cycle, for human health and well-being. Simply put, it is vital for us. Yet, it is being lost globally at devastating rates: Since 1970, there was on average a 69% decrease in population sizes of mammals, birds, amphibians, reptiles and fish, with even more alarming losses of 94% in the highly biodiverse tropical Americas (WWF, 2022).
The impact of climate change on biodiversity is significant. Across terrestrial, freshwater, and ocean ecosystems, climate change is already driving changes to the structure of ecosystems and the timing of ecological events like species migration or reproduction cycles (IPCC, 2022). A climate change-driven redistribution of species is also underway, as species migrate to latitudes or elevations that allow them to stay within suitable ecological zones amid a changing climate (IPCC, 2022). Still, it is expected that the capacity of most ecosystems to adapt will be exceeded by the severity of climate change impacts (Pörtner et al., 2021). For example, the Amazon forest is at risk of significant forest loss under a drying climate (Yadvinder Malhi et al. 2008), and the risk of extinction in biodiversity hotspots globally increases approximately 10 times pre-industrial levels under all warming projections of 1.5°C to 3°C (IPCC, 2022). In Europe, the Mediterranean biodiversity hotspot has experienced an increase in wildfires and droughts that has been attributed to climate change (IPCC, 2022). As a whole, climate change modifies and amplifies the influence of land use change (e.g., deforestation) on biodiversity loss (Mantyaka-Pringle et al. 2015).
Biodiversity can help with climate change adaptation and mitigation. Nature makes a vital contribution to climate change mitigation, through the reabsorption of more than 30 percent of anthropogenic CO2 emissions into the land surface (2010-2019) (Friedlingstein et al 2020). For example, the Amazon forest is a crucial biodiversity hotspot and stores approximately 120 Pg C in biomass carbon while also acting as a carbon sink of approximately 0.6 Pg C per year (Yadvinder Malhi et al. 2008). Meanwhile, biodiversity and nature also influence our ability to adapt to the impacts of climate change. For example, biodiversity improves forest resilience to many types of disturbance including climate change (Thompson et al. 2009). As a result, some efforts to mitigate climate change, such as with monoculture afforestation, can affect biodiversity in ways that can paradoxically reduce the landscape’s resilience to the impacts of climate change.
Solutions at the climate-biodiversity nexus
There is evidence that actions to halt biodiversity loss can also often benefit climate mitigation (Shin et al., 2022). Part of the reabsorption of anthropogenic carbon emissions into the land surface is forest re-growth. As such, avoiding forest degradation or loss is not only a vital way of preventing the loss of forest habitat and species, it also makes a vital contribution to carbon storage. Similarly, at the edge of the land system, coastal habitats and ecosystems contain large amounts of biological diversity. These habitats protect soils from oxidation, preventing CO2 from being released into the atmosphere. In fact, the amount of carbon sequestration per unit of coastal vegetated area is much higher than terrestrial forests, highlighting the importance of preventing the degradation and destruction of this important ecosystem. For example, in the Sundarbans, India-Bangladesh, maintaining mangrove forests by implementing protected areas provides habitat for many species, including the endangered Bengali tiger, whilst also regulating GHG emissions (Case Study 6, in Shin et al., 2022).
The impact of actions for climate mitigation and adaptation on biodiversity is mixed. On one hand, nature-based solutions are solutions that work with and enhance nature to help address societal challenges (Seddon et al. 2020) and are used to improve resilience to floods and droughts under a changing climate. For example, intact ecosystems like mangroves provide a natural buffer to more frequent and severe weather events like coastal storms or floods (Temmerman et al. 2023). On the other hand, the shift toward renewable energy to mitigate climate change has variable influences on biodiversity. Solar takes up significant land and wind power can have an impact on local bird and bat populations, and bioenergy crops can increase competition for land in ways that negatively influence biodiversity (Immerzeel et al. 2014).
These complexities and trade-offs highlight the importance of generating solutions that maximise synergies within the biodiversity nexus, where climate change adaptation and mitigation strategies consider both a reduction in GHG emissions and climate risk, but also the impact on biodiversity.
Call to action
In the words of the UN Secretary-General Antonio Guterres:
“Our planet has just endured a season of simmering -- the hottest summer on record. Climate breakdown has begun. Scientists have long warned what our fossil fuel addiction will unleash. Surging temperatures demand a surge in action. Leaders must turn up the heat now for climate solutions. We can still avoid the worst of climate chaos – and we don’t have a moment to lose” (WMO, 2023).
We must act now to address the climate crisis if we want a liveable future for ourselves and our children. And we must consider the role of biodiversity and nature in the process. The risks of human-driven biodiversity loss through agricultural intensification and deforestation are now compounded by impacts of climate change, and “the collapse of ecosystems will threaten the wellbeing and livelihoods of everyone on the planet” (Linda Krueger, the Nature Conservancy, 2020). Thankfully, reversing biodiversity loss not only secures our natural environment but is also part of the solution to the climate crisis.
One way of accelerating positive change is to pursue solutions that maximise synergies and minimise trade-offs across biodiversity loss and climate change. Individual actions that simultaneously reduce greenhouse gas emissions and benefit biodiversity include reducing car usage over short distances and walking or cycling instead, reducing consumption of meat and dairy and switching to local, more plant-based diets, and restoring local natural spaces, such as gardens, to promote carbon storage and foster greater plant diversity for wildlife. At an institutional level, governments and businesses can divest away from fossil fuels to drastically reduce emissions and instead focus on renewable energy generation, whilst considering the specific placement of new projects to prevent further biodiversity loss as a result of land use change. Reallocating food subsidies away from intensive meat and dairy farming, towards fruit, vegetables and legumes would reduce the requirement for feed imports from highly biodiverse, high-deforestation risk areas such as the Amazon, reducing overall land use requirements and the environmental impact of food production. We urge everyone to consider the role they play in solving these intersecting crises.
The BIONEXT project also joins the fight for nature and biodiversity. We are producing new evidence to better understand how biodiversity underpins the food we eat, the water we drink, and many other aspects of life, and is thus fundamental for a sustainable society. This work includes a review on the current state of the biodiversity nexus, which includes consideration of how biodiversity influences climate change, and vice versa. We are also evaluating options for transformative change toward solutions that maximise synergies across the biodiversity nexus. We look forward to leveraging the findings of the BIONEXT project to facilitate the transformative change required to do so.
Written by Scenario Developer Anita Lazurko (UK Centre for Ecology & Hydrology) and Postdoctoral Researcher Joanna Raymond (Karlsruhe Institute of Technology)