To say that climate change affects community health is a profound understatement. The planet has warmed by 1 degree Celsius compared to pre-industrial levels, with effects that are already apparent: melting glaciers have contributed to a steady rise in sea levels since 1880;1 extreme weather events are getting more extreme2 (especially deadly heat waves3); and increasingly unpredictable climate patterns are reducing global food supplies.4
In October 2018, the Intergovernmental Panel on Climate Change (IPCC) released a report with an urgent message: at humanity’s current rate of greenhouse gas emissions, we’re on track to increase global temperatures by 3 degrees Celsius by 2100, with dire consequences for human health well before then. Most alarmingly, the report noted that we only have until 2030 to reduce emissions by almost half—which would require a radical remaking of the global economy—in order to meet the 1.5 degree threshold for avoiding “catastrophic” warming. That’s… 11 years from now.
A separate report on Earth’s biodiversity released this year found that deforestation is a leading driver of accelerating extinction rates, and underscored that human survival depends on intact, biodiverse ecosystems.
The good news is that we already have the tools we need to ensure that communities can not only adapt to a warmer world, but thrive in it—if we act quickly. In addition to drastic cuts in fossil fuel emissions, reforestation and preservation of existing forests have emerged as two of the most feasible and effective strategies for addressing the climate and biodiversity crises.5
In an increasingly urbanizing world, parks provide space for planting new trees in otherwise fully-developed places. (So do under-used parking lots, but that’s a conversation for another day.) There’s more good news: young trees are better at absorbing carbon from the atmosphere than mature trees,6 which means that tree-planting efforts in parks would have an immediate, meaningful impact. In addition to their carbon-sequestering abilities, existing tree canopies in parks clean pollutants from the air and can reduce the urban heat-island effect by as much as 15 degrees.7
Parks are also an ideal setting for greenways and bike lanes, which encourage people to drive less and emit fewer asthma-inducing and climate- change-accelerating vehicle emissions. Parks can also mitigate the effects of some natural disasters. For example, natural spaces reduce flooding impacts by increasing the permeability of land and absorbing and cleaning storm water runoff.8
After decades of research exploring the various impacts of parks on communities, a global meta-study in 2018 declared that there is clear evidence that living close to natural places improves health. The analysis found that proximity to parks and greenspaces reduces the risk of diabetes, heart disease, blood pressure, early death, and preterm birth, and that it even decreases cortisol levels, a key marker of mental and physical stress. What’s not yet understood is what proportion of these benefits are caused directly by greenspaces themselves; caused indirectly from things like increased opportunities for physical activity, potential for social connection, and better air quality; or correlated with socio-economic characteristics of park-rich neighborhoods.
A more recent study offers two important insights that may begin to answer that question. First, it found that at least two hours of “direct exposure” to nature (as in, time actually spent in a natural space as opposed to just living near one) increased self-reported well-being over a one-week period. Second, the study also accounted for whether participants did or did not meet recommended levels of physical activity during the week, and found that time spent outdoors further increased well-being for both groups. These are important distinctions, because they suggest that natural spaces might offer direct health benefits in addition to the well-documented indirect ones. However, the study had notable limitations and stopped short of recommending a specific “dose.”
Despite lingering gaps in research, a growing number of doctors are prescribing time in parks as a component of patients’ treatment plans. Organizations like Park Rx America and the National Park Rx Initiative offer resources to help professionals prescribe parks and start park prescription programs. The Children and Nature Network, recognizing the unique health and development impacts that time spent outdoors has on children, is leading a movement to increase equitable access to nature.
One often-overlooked caveat buried in these studies is that the health benefits of parks and natural spaces hinge on specific characteristics. The study that linked health benefits with proximity to greenspace described those spaces as “undeveloped land with natural vegetation” as well as urban greenspaces and street greenery. The study that linked two hours in nature with increased well-being also noted that “experiences may be better in more biodiverse settings.” And one analysis of U.S. Medicaid spending found that counties with significant forest and shrub land spent less per person, but found no health savings associated with grasslands and urban vegetation.
In the United States, a “park” can refer to thousands of acres of wilderness, an asphalt basketball court, and everything in between. Increasing the number of parks and safe, affordable access to them is an important strategy for improving community health now and over the long term. However, because parks benefit health on both an individual and collective scale, their potential impacts will depend not just on their characteristics, but also on how accessible they are.
Over the next few weeks, we’ll highlight organizations and communities working to address these concerns. We’ll also share resources for increasing park access in communities and discuss issues related to equity and parks. Has your community improved park access? We want to hear about it! Share your story with me at firstname.lastname@example.org.
In the meantime, we should probably all go plant a tree.
Photo by Jim Roberts, distributed under a Creative Commons license.