By Bradley J. Cardinale 5 minute Read
As spring phases into summer in North America, with trees flowering and birds migrating, nature seems abundant. In fact, however, the Earth is losing animals, birds, reptiles, and other living things so fast that some scientists believe the planet is entering the sixth mass extinction in its history.
This fall, the United Nations will convene governments from around the world in Kunming, China, to establish new goals for protecting Earth’s ecosystems and their biodiversity—the variety of life at all levels, from genes to ecosystems.
Some people, cultures, and nations believe biodiversity is worth conserving because ecosystems provide many services that support human prosperity, health, and well-being. Others assert that all living things have a right to exist, regardless of their usefulness to humans. Today, there’s also growing understanding that nature enriches our lives by providing opportunities for us to connect with each other and the places we care about.
As a conservation biologist, I’ve been part of the effort to value biodiversity for years. Here’s how thinking in this field has evolved, and why I’ve come to believe that there are many equally valid reasons for protecting nature.
Defending every species
Conservation biology is a scientific field with a mission: protecting and restoring biodiversity around the world. It came of age in the 1980s, as humans’ impact on the Earth was becoming alarmingly clear.
In a 1985 essay, Michael Soulé, one of the field’s founders, described what he saw as the core principles 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 should act to save biodiversity even if sound science isn’t available to inform decisions.
To critics, Soulé’s principles sounded more like environmental activism than science. What’s more, not everyone agreed then or now that biodiversity is inherently good.
This estimate included such services as predators controlling pests that would otherwise ruin crops; pollinators helping to produce fruits and vegetables; wetlands, mangroves, and other natural systems buffering coasts against storms and flooding; oceans providing fish for food; and forests providing lumber and other building materials.
Researchers have refined their estimates of what these benefits are worth, but their central conclusion remains the same: Nature has shockingly high economic value that existing financial markets don’t account for.
A second group began to quantify the non-monetary value of nature for human health, happiness and well-being. Studies typically had people take part in outdoor activities, such as strolling through a green space, hiking in the woods or canoeing on a lake. Later, they measured the subjects’ physical or emotional health.
This research found that spending time in nature tended to reduce blood pressure, lower hormones related to stress and anxiety, decrease the probability of depression and improve cognitive function and certain immune functions. People exposed to nature fared better than others who took part in similar activities in non-natural settings, such as walking through a city.
Losing species weakens ecosystems
A third line of research asked a different question: When ecosystems lose species, can they still function and provide services? This work was driven mainly by experiments where researchers directly manipulated the diversity of different types of organisms in settings, ranging from laboratory cultures to greenhouses, plots in fields, forests, and coastal areas.
By 2010, scientists had published more than 600 experiments, manipulating over 500 groups of organisms in freshwater, marine, and land ecosystems. In a 2012 review of these experiments, colleagues and I found unequivocal evidence that when ecosystems lose biodiversity, they become less efficient, less productive, and less stable. And they are less able to deliver many of the services that underlie human well-being.
For example, we found strong evidence that loss of genetic diversity reduced crop yields, and loss of tree diversity reduced the amount of wood that forests produced. 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 also showed that it was possible to develop robust mathematical models that could predict reasonably well how biodiversity loss would affect certain types of valuable services from ecosystems.
Many motives for protecting nature
For years, I believed that this work had established the value of ecosystems and quantified how biodiversity provided ecosystem services. But I’ve come to realize that other arguments for protecting nature 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 were doing it because of the economic value of biodiversity or its role in sustaining ecosystem services.
Instead, they’ve shared stories about how they grew up fishing with their father, held family gatherings at a cabin, or canoed with someone who was important to them. They wanted to pass on those experiences to their children and grandchildren to preserve familial relationships. Researchers increasingly recognize that such relational values—connections to communities and to specific places—are one of the most common reasons why people choose to conserve nature.
I also know many people who hold deep religious beliefs and are rarely swayed by scientific arguments for conservation. But when Pope Francis published his 2015 encyclical Laudato si’: On Care for Our Common Home and said God’s followers had a moral responsibility to care for his creation, my religious relatives, friends, and colleagues suddenly wanted to know about biodiversity loss and what they might do about it.
Surveys show that 85% of the world’s population identifies with a major religion. Leaders of every major religion have published declarations similar to Pope Francis’ encyclical, calling on their followers to be better stewards of Earth. Undoubtedly, a large portion of humanity assigns moral value to nature.
Research clearly shows that nature provides humanity with enormous value. But some people simply believe that other species have a right to exist, or that their religion tells them to be good stewards of Earth. As I see it, embracing these diverse perspectives is the best way to get global buy-in for conserving Earth’s ecosystems and living creatures for the good of all.
Bradley J. Cardinale is department head, ecosystem science and management, Penn State.
