A change of perspective

The CHN building on the ETH Zentrum campus is generally a hive of activity, with researchers writing papers and students working on assignments between lectures. Equally buzzing is the basement of the Department of Environmental System Sciences, where some 50 young bumblebee queens are busy establishing new colonies in a climate chamber. On hand to monitor this process is Sarah Richman, an ecologist from the Plant Ecology group led by Janneke Hille Ris Lambers.

Richman hopes the bumblebees will provide clues about how a changing climate is affecting interactions between species – in this case, between plants and their pollinators. Her plan is to simulate global warming by settling the colonies at different altitudes in the mountains and then tracking their fitness and feeding behaviour. In a warming climate, the flowering period of plants often falls out of sync with their natural pollinators – a phenomenon known as temporal mismatch. “Communities that are more diverse are more resilient to these kinds of negative effects,” says Richman. “The problem is that biodiversity – like so many other things – is in crisis.”

Biodiversity refers to the variety of living organisms at the level of ecosystems, species and genes. Together with abiotic environmental factors such as water, temperature and light, it forms the basis of our ecosystems. “All ecosystems – from the smallest creatures to the global biosphere – are shaped by species and the interactions between them,” says Jaboury Ghazoul, Professor of Ecosystem Management.

Depending on their scale and frequency, human activities can have a significant impact on the dynamics of these biological systems. Yet the resilience of ecosystems is astonishingly high. “It was only recently that we discovered that tropical systems – which were previously regarded as particularly fragile – are actually incredibly resilient to disruption,” says Ghazoul. Even after severe degradation, many tropical forests can regrow within 100 to 150 years, provided some forest patches remain. Most of the biodiversity, soil organisms and nutrient cycles also recover during this time.

The impact of species loss

Nonetheless, scientists remain particularly concerned about long-term global impacts such as climate change. “We simply don’t know the extent to which species and communities can adapt and recover,” says Ghazoul. He suspects that, in some cases, new ecosystems will emerge with a different mix of species. But he argues that we have already lost many important and interesting ecosystems, and that the number of these losses will continue to increase.

“There are certain species that some people won’t care about losing – or won’t notice when they’re gone,” says Ghazoul. “But we should be looking at this as a system.” Biodiversity loss has far-reaching consequences: as species disappear, ecosystem functions degrade. Soil quality may be affected, leading to erosion and nutrient loss. This, in turn, can transform entire river systems, reshaping the habitat of fish and invertebrates. Silt accumulates in rivers and is washed into the ocean, where it smothers and kills coral reefs, while the influx of nutrients encourages the growth of algae. This depletes fish stocks, thus impacting the livelihood of many coastal dwellers. But how much are we willing to support species conservation if it means giving up other benefits? From agriculture and energy production to the infrastructure that improves our quality of life, every decision we make has an impact on the environment. And each of us has our own picture of what the future should look like. “We need to recognise that everyone’s values are equally legitimate, even when they conflict with each other,” says Ghazoul. “As a society, the only way we can negotiate compromises is by showing mutual respect and acknowledging the validity of alternative viewpoints.”