The biodiversity of our planet sustains us. From the air we breathe and the water we drink, to the soil we sow and the fuel we use. But Earth does more than provide the basic necessities that allow humans to survive and prosper. Our ability to experience nature could have the capacity to improve our well-being and consequently mental health.

We readily spend our hard-earned money and time on a variety of pursuits to experience nature’s wonders: from expensive safaris to sedate bird watching in the garden. And we have good reason to – a number of studies show that by engaging with the earth’s natural diversity there are health benefits to be had. But, with the earth’s biodiversity in decline, it’s worth taking a look at how this will in turn affect human well-being and health.

In a recent study of ours we argue that biodiversity loss could threaten the well-being benefits we get from nature, with potential repercussions for human mental health. Mental health disorders already affect nearly nine million people in the UK and are projected to cost £88.5 billion by 2026. So, if biodiversity loss does impact on mental health, it could be even more costly than previously thought.

Cultural value

Biodiversity has cultural value, which is evident across the globe. Specific species of flora and fauna are often central to our cultural identity. Most countries have an adopted animal or plant for a national symbol: the oak tree and the lion, for example, are strongly associated with British identity. Further afield, New Zealand has the kiwi bird, the resplendent quetzal is a bird of legend in Guatemala and Lebanon has its cedars.

Many people enjoy experiencing nature and are willing to contribute towards its future conservation through charities and public spending. Plus, many of us regularly devote our time to biodiversity conservation projects, such as the RSPB’s Big Garden Birdwatch in the UK and the Audubon Society’s Great Backyard Bird Count in the USA. Ecotourism is also hugely popular and international organisations use the cultural values we place on enigmatic species to encourage our donations.

Declining biodiversity means fewer opportunities to appreciate and value it. This could have a significant effect on our well-being and subsequently our mental health. Although we are still learning about these complex relationships, evidence from other aspects of health research, as highlighted below, suggests that health may well be negatively impacted by biodiversity loss.

Sensitive to change

We know that people are sensitive to apparently trivial changes because of existing cultural associations. The colour of a tablet, for example, can affect our reported health outcomes: blue tablets are more effective as depressants, as the colour blue is culturally associated with calm and quietness; and red tablets are more effective as stimulants, as the colour red is associated with energy and excitement.

Being aware of environmental problems can affect our mental health. Episodes of drought and flooding have been associated with higher levels of depression, anxiety and stress within communities. There is also a growing body of evidence to suggest that people who spend less time in high quality natural environments report greater health problems, higher levels of stress and slower recovery from illness than those who are exposed to nature more frequently.

All the evidence points to biodiversity loss having a negative impact on human well-being and health. If we continue to lose species at current extinction rates (which are estimated at 100-1000 times the natural rate) there is a real threat that not only will we continue to degrade global ecosystems, but we will also add to the burden of non-communicable disease, such as mental health illnesses.

We still know relatively little about the relationship between biodiversity and human well-being and health. However, it is clear that we need to better understand the mechanisms and how to best conserve biodiversity to reduce the occurrence and costs of ill health. If change to our planet’s biodiversity plays even a minor role in contributing to mental ill-health, the economic and health costs to society could be enormous.