National parks worldwide are worth about $8.7 trillion ($US6 trillion) a year in the improved mental health of their visitors, according to initial estimates published by a team of Griffith University researchers.
Griffith ecologists, psychologists and economists led the peer-reviewed Perspective 'Economic value of protected areas via visitor mental health', which has been published in the prestigious journal Nature Communications.
The Perspective study was jointly funded by Griffith University, Queensland Parks and Wildlife Service and Parks Victoria.
The team included Professor Ralf Buckley, Professor Paula Brough, Professor Chris Fleming, Associate Professor Neil Harris, Dr Ali Chauvenet, Leah Hague, Elisha Roche and Dr Ernesta Sofija from across Griffith's School of Environment and Science, Centre for Work Organisation and Wellbeing, Environmental Futures Research Institute, Griffith Business School and School of Medicine.
Using a concept called quality-adjusted life years, which measured a person's ability to carry out the activities of daily life free from pain and mental disturbance, the researchers estimated the economic value of national parks using data collected from a representative sample of the Australian population in the states of Queensland and Victoria (19,674).
They used these data to estimate the value for the whole of Australia and globally and found a direct link between visits to protected areas and individual mental health.
For Australia, the team estimated the annual health services value of Australia's national parks was around $145 billion ($US100 billion) a year.
"The article suggests several ways to calculate health services value, and these numbers are from just one of those methods – now we need to extend that research to other methods and other countries," Professor Buckley said.
"Protected areas are there for conservation, which gives us a liveable planet and underpins our entire economy, but conservation is not very powerful politically. People and politicians pay more attention to health, because it affects them personally."
"This value already exists, it just was not recognised. People already visit parks to recover from stress. In healthcare terms, it's patient-funded therapy. Without parks, costs of poor mental health in Australia would rise by $145 billion a year."
Currently, the costs of poor mental health in Australia amount to approximately 10% of GDP, and the researchers' estimates indicate that these costs could be 7.5% higher without protected areas such as national parks.
The economic costs of poor mental health include treatment, care and reduced workplace productivity and affect individuals, families, employers, insurers and taxpayers.
The health-related benefits of spending time in nature are thought to include improved attention, cognition, sleep and stress recovery, but the economic value of national parks is in terms of their impact on the mental health of their visitors has been previously unknown.
"The next step will be to test how mental health benefits depend on individual personalities, and on particular aspects of park visits," Dr Chauvenet said.
"It's possible that park visits could then become a routine part of the healthcare system, prescribed by doctors and funded by insurers.
"From a park management perspective, it means that maximum economic return to government treasuries may be from investing in low-key hiking tracks, lookouts, and other visitor facilities, to attract people to visit with their children as often as possible."
The team stated the findings were based on calculations from pilot studies and more detailed analysis would be required to refine the estimates.
