By Bradley J. Cardinale
As spring turns to summer in North America, with trees blooming and birds migrating, nature seems abundant. In fact, however, the Earth is losing animals, birds, reptiles and other living things so rapidly that some scientists believe the planet is entering the sixth mass extinction in its history.
This fall, the United Nations convene governments around the world in Kunming, China, to establish new goals for the protection of the Earth’s ecosystems and their biodiversity – the variety of life at all levels, from genes to ecosystems.
Some people, cultures and nations believe that biodiversity is worth conserving because ecosystems provide many services that support human prosperity, health and well-being. Others claim that all living things have the right to exist, regardless of their usefulness to humans. Today, there is also a growing understanding that nature enriches our lives by providing opportunities to connect with each other and the places we care about.
Like a conservation biologist, I have been involved for years in the effort to promote biodiversity. Here’s how thinking in this area has evolved and why I’ve come to believe that there are many equally valid reasons to protect nature.
Biodiversity describes both the amount of genetic diversity within species and the range of species that make up ecosystems.
Conservation biology is a scientific field whose mission is to: protect and restore biodiversity around the world. It came of age in the 1980s as man’s impact on the Earth became increasingly clear.
In a 1985 essay, Michel Souléone of the founders of the domain, described what he considered to be the fundamentals of conservation biology. Soulé argued that biological diversity is inherently good and should be conserved because it has intrinsic value. He also proposed that conservation biologists act to save biodiversity even if sound science is not available to inform decisions.
For critics, Soulé’s principles sounded sounds more like environmental activism than science. Also, not everyone agreed then or now that biodiversity is inherently good.
After all, wild animals can destroy crops and endanger human lives. Contact with nature can lead to disease. And some conservation initiatives have people displaced from their land or prevented the development which could otherwise improve people’s lives.
Valuing the services of nature
Soule’s essay prompted many researchers to push for a more scientific approach to conservation. They sought to directly quantify the the value of ecosystems and the roles that species have played in them. Some researchers have focused on calculating the value of ecosystems to humans.
They came to the preliminary conclusion that the total economic value of the world’s ecosystems was worth an average of $33 trillion per year in 1997 dollars. At the time, that was almost twice the aggregate value of financial markets around the world.
This estimate included services such as predators controlling pests that would otherwise ruin crops; pollinators contributing to the production of fruits and vegetables; wetlands, mangroves and other natural systems buffering coastlines from storms and floods; the oceans providing fish for food; and forests providing timber and other building materials.
The researchers refined their estimates of the value of these benefitsbut their central conclusion remains the same: nature has a surprisingly high economic value that existing financial markets do not take into account.
Forests and fields help supply New York City with high-quality drinking water, most of which does not need to be filtered.
A second group began to quantify the non-monetary value of nature for human health, happiness and well-being. The studies generally had people participate in outdoor activities, like taking a walk in a green space, hiking in the woods, or canoeing on a lake. Later they measured the physical or emotional health of subjects.
This research found that spending time in nature tended to lower blood pressure, decrease hormones related to stress and anxiety, decrease the likelihood of depression, and improve cognitive functions and certain immune functions. People exposed to nature fared better than others who participated in similar activities in unnatural environments, such as walking around a city.
Loss of species weakens ecosystems
A third line of research asked a different question: when ecosystems lose species, can they still operate and provide services? This work was conducted primarily through experiments where researchers directly manipulated the diversity of different types of organisms in environments ranging from laboratory crops to greenhouses, to plots in fields, forests and coastal areas.
By 2010, scientists had published over 600 experiments, manipulating over 500 groups of organisms in freshwater, marine and terrestrial ecosystems. In a review of these experiments in 2012, colleagues and I found unequivocal evidence that when ecosystems lose their biodiversity, they become less efficient, less productive and less stable. And they are less able to provide many services that underpin human well-being.
For example, we found strong evidence that the loss of genetic diversity reduced crop yields and that the loss of tree diversity reduced the amount of wood produced by forests. We also found evidence that oceans with fewer fish species produced less reliable catches and that ecosystems with lower plant diversity were more prone to invasive pests and diseases.
We have also shown that it is possible to develop robust mathematical models capable of reasonably predicting how biodiversity loss would affect certain types of valuable ecosystem services.
Many reasons to protect nature
For years, I believed that this work had established the value of ecosystems and quantified how biodiversity provided ecosystem services. But I have come to realize that other arguments in favor of nature conservation are just as valid, and often more convincing for many people.
I have worked with many people who donate money or land to support conservation. But I’ve never heard anyone say they’re doing it because of the economic value of biodiversity or its role in maintaining ecosystem services.
Instead, they shared stories of how they grew up fishing with their dad, hosting family get-togethers in a cabin, or canoeing with someone important to them. They wanted to pass on these experiences to their children and grandchildren to preserve family relationships. Researchers are increasingly recognizing that such relational values – connections to communities and to specific places – are one of the most common reasons people choose to conserve nature.
I also know many people who hold deep religious beliefs and who are rarely influenced by scientific arguments for conservation. But when Pope Francis issued his 2015 encyclical Laudato si’: on the care of our common home and said that God’s followers have a moral responsibility to care for his creation, my parents, friends and religious colleagues suddenly wanted to know what biodiversity loss was and what they could do about it.
Surveys show that 85% of the world’s population identifies with a major religion. Leaders of all major religions have issued statements similar to Pope Francis’ encyclical, calling on their followers to be earth’s best stewards. Undoubtedly, a large part of humanity attributes a moral value to nature.
Research clearly shows that nature provides enormous value to humanity. But some people simply believe that other species have a right to exist, or that their religion tells them to be good stewards of the Earth. In my view, embracing these diverse perspectives is the best way to gain global buy-in for the conservation of Earth’s ecosystems and living creatures for the benefit of all.