Connecting Global Priorities Biodiversity and Human Health

since the mid-twentieth century than at any other
time in recorded human history. Among the 24
categories of ecosystem services assessed, 15 of
them were in a state of decline, the majority of
them regulating and supporting services (MA
2005). Declining services include pollination,
the ability of agricultural systems to provide pest
control, the provision of freshwater, marine fishery
production, and the capacity of the atmosphere
to cleanse itself of pollutants. Most ecosystem
services that were found to be increasing were
provisioning services, including crops, livestock
and aquaculture. Consumption was also increasing
of all services across all four categories. These
increases have helped to generate and sustain
the increases in human health and well-being
seen over the same period. However, the decline
of many other ecosystem services – mostly the
regulating and supporting services – threatens
to undermine this progress, presenting threats
to human health and well-being (Chivian and
Bernstein 2008; Haines-Young and Potschin 2010;
McMichael and Beaglehole 2000), several of which
are described throughout this technical volume.
In general, aggregate terms, socioeconomic
progress has benefited human health and wellbeing,
but at a cost to the underlying natural
resource base. Raudsepp-Hearne et al. (2010)
examined several hypotheses to explain this
apparent paradox and call for efforts to expand
our understanding of the complex cross-scale
interactions between ecosystem services, human
activities and human well-being.
3.3 Biodiversity loss, biosphere
integrity and tipping points
Ecosystem management strategies aimed at
maximizing conservation and public health
co-benefits must consider that systems have
emergent properties that are not possessed by
their individual components: they are more
than the sum of their parts. One example is the
resilience of ecosystems to absorb shock in the
face of disturbance (such as pests and disease,
climate change, invasive species, or the harvesting
of crops, animals or timber) and return to their
original structure and functioning. Ecosystems can
be transformed if a change in ecosystem structure
crosses a given threshold. Structural changes
may be manifested as a result of the removal
of key predators or other species from the food
web (Thomson et al. 2012), the simplification of
vegetation or soil structure, increased or decreased
aridity, species loss and many other factors.
Biodiversity loss is continuing, and in many cases
increasing (Butchart et al. 2010; Tittensor et al.
2014). Biodiversity loss has been identified as one
of the most critical drivers of ecosystem change
(Hooper et al. 2012). Changes in the diversity of
species that alter ecosystem function may directly
reduce access to ecosystem services such as food,
water and fuel, and also alter the abundance of
species that control critical ecosystem processes
essential to the provision of those services (Chapin
et al. 2000).
Ecosystem regime shifts, including “tipping
points”, have been widely described and
characterized at local levels (for example,
eutrophication of freshwater or coastal areas
due to excess nutrients; collapse of fisheries
due to overfishing; shifts of coral reefs to algaedominated
systems; see Sheffer 2009; CBD 2010).
There is growing concern that regime shifts
could occur at very large spatial scales over the
next several decades, as human–environment
systems exceed limits because of powerful and
widespread driving forces that often act in
combination: climate change, overexploitation of
natural resources, pollution, habitat destruction,
and the introduction of invasive species (Leadley
et al. 2014; Barnosky et al. 2012; Hughes et al.
2013). Cardinale et al. (2012) suggest that the
impacts of biodiversity loss on ecological processes
might be sufficiently large to rival the impacts of
climate change and many other global drivers of
environmental change.
Leadley et al. describe scenarios for regional-scale
shifts that would have large-scale and profound
implications for human well-being (Leadley
et al. 2014). The unprecedented pressures of
human activity on biodiversity and on the
earth’s ecosystems may also lead to potentially
irreversible consequences at a planetary scale,
and this prospect has led to the identification of
36 Connecting Global Priorities: Biodiversity and Human Health