With
climate change accelerating and its effects exacerbating other
geopolitical and development crises, the role of environmental
protection in preserving and improving human well-being has become
starkly apparent. This recognition lies at the heart of the concept of
“planetary health,” which focuses on the health of human civilisation
and the condition of the natural systems on which it depends.
The
concept’s logic is simple: if we try to deliver better health to a
growing population, without regard for the health and security of our
natural resources, we will not just struggle to make new strides; we
will reverse the progress already made. Where things get complicated is
in applying the concept, particularly when addressing the nexus of water
services, health, and ecosystem integrity.
Since at least 1854, when
John Snow discovered that cholera was spread through contaminated water
supplies in central London, humans have understood that polluted water
is bad for our health. The degradation of freshwater ecosystems often
brings disease, just as the protection or strengthening of such
ecosystems improves health outcomes.
But, while it is now well
understood that progress in one area improves outcomes in another, such
co-beneficial dynamics often are insufficient to spur investment in both
areas.
For example, investing to protect a watershed can also
protect biodiversity and improve water quality in associated rivers,
thereby benefiting human health. But if the goal is explicitly to
improve human health, it might be more cost-effective simply to invest
in a water-treatment plant.
A more compelling dynamic is
complementarity: when investment in one area increases the returns on
investment in other areas. In this scenario, investments in protecting a
watershed would aim not just to produce returns directly, but also to
boost the returns of simultaneous investments in human health.
Complementarity produces mutually reinforcing dynamics that improve
outcomes across the board.
A well-functioning water sector already
attempts to balance complementary interventions. Indeed, such a system
amounts to a multidisciplinary triumph of human ingenuity and
co-operation – involving engineering, hydrology, governance, and urban
planning – with far-reaching complementary impacts on both human health
and economic development.
In 1933, through the Tennessee Valley
Authority Act, the United States established an agency whose purpose was
to build hydroelectric dams on the Tennessee River. That effort
benefited industry, agriculture, flood control, and conservation
throughout the Tennessee Valley watershed, until then one of the
country’s most disadvantaged regions.
Since then, governments
worldwide have recognised the potential of water infrastructure to
complement other economic and social policies, including those intended
to improve health outcomes. It is no coincidence that one of the World
Bank’s largest lending portfolios – $35bn worth of investments –
comprises water projects.
But understanding the potential of
complementarity is just the first step. To maximise results, we must
design a coherent strategy that takes full advantage of the dynamic, at
the lowest possible cost. The question is whether there is an optimal
mix of environmental protection and direct health interventions on which
policymakers can rely to maximise investment returns for both.
A
recent analysis suggests that, in rural areas, a 30% increase in
upstream tree cover produces a 4% reduction in the probability of
diarrhoeal disease in children – a result comparable to investing in an
improved sanitation facility. But, if that is true, we have yet to
determine at what point reforestation becomes a better investment than
improving sanitation, let alone increases the returns of other health
interventions by the highest possible amount.
Another study found
that an estimated 42% of the global malaria burden, including a
half-million deaths annually, could be eliminated through policies
focused on issues like land use, deforestation, water resource
management, and settlement siting. But the study didn’t cover the
potential benefits of employing insecticide-treated nets as a tool for
fighting malaria, ruling out a comparison of the two investments’
returns.
Worldwide, around 40% of cities’ source watersheds show high
to moderate levels of degradation. Sediment from agricultural and other
sources increases the cost of water treatment, while loss of natural
vegetation and land degradation can change water-flow patterns. All of
this can adversely affect supply, thereby increasing the need to store
water in containers – such as drums, tanks, and concrete jars – that
serve as mosquito larval habitats. Can we show that ecological
restoration of the watershed could do more than just insecticides or
mosquito nets to support efforts to reduce malaria (and dengue) in
cities?
In all of these cases, finding the best option requires
knowing not just the relative contribution of different interventions,
but understanding their complementarity. In a world of limited
resources, policymakers must prioritise their investments, including by
differentiating the necessary from the desirable. To that end, finding
ways to identify and maximise complementarity is vital.
Some 2.1bn
people worldwide lack access to safe, readily available water at home,
and more than twice as many – a whopping 4.5bn – lack safely managed
sanitation, severely undermining health outcomes and fuelling river
pollution. With a growing share of the world’s population – including
many of the same people – feeling the effects of environmental
degradation and climate change firsthand, finding solutions that
simultaneously advance environmental protection, water provision, and
health could not be more important. Global health and conservation
professionals must co-operate more closely to find those solutions – and
convince policymakers to pursue them. – Project Syndicate
* Giulio Boccaletti is Chief Strategy Officer and Global Managing Director for Water at The Nature Conservancy.