Transcript Biodiversity tipping points at local scale in biodiversity

Biodiversity tipping points and
biodiversity-dependent
socio-ecological systems
Pathways for human
adaptation?
Prof. Patricia Howard, University of
Kent at Canterbury and Wageningen
University, the Netherlands
([email protected])
Dr. Thomas Thornton, Environmental
Change Institute, Oxford
Overview: complex, novel topic
• Nature of biodiversity tipping points (BTP) per se and at
local scale?
• Nature of highly biodiversity-dependent societies
(HBDS)?
• Consequences of BTP for HBDS and adaptation of HBDS
given BTP?
• Planetary consequences?
Why biodiversity change?
• Biodiversity loss is a major driver of global environmental
change (Hooper et. al. 2012) and it is probable that there is a
mass extinction underway
• Environmental change impacts humans principally through
changes in flora and fauna
• Biodiversity change has many other drivers besides climate
change
What is biodiversity change?
•
Species richness (number of species)
•
Species abundance (how common, or rare)
•
Species phenology, range (timing of budburst, leaf fall,
reproduction; geographic dispersion (habitat) and mobility
•
Can reorganise entire ecosystems - including tipping
•
Drivers: Land use change, habitat fragmentation, invasive
species, pollution, pathogens, degradation, over-harvesting,
climate change
What are ‘biodiversity tipping points’?
• ‘Tipping point’ concept only recently linked to biodiversity
but not yet systematically explored (GBO4)
• Majority of ecosystem tipping points may be related to
biodiversity (diversity, abundance, or functionally
important species)
• Dynamics: climate-vegetation feedbacks, transitions in
semi-arid vegetation, species extinctions in fragmented
landscapes, etc. (Scheffer 2009, Critical Transitions).
Possible regional biodiversity tipping points
(Leadley et al. 2010)
• Amazon forest dieback
• African Sahel desertification
• Island ecosystems collapse from invasives
• Invasion of tundra by boreal forests
• Coastal terrestrial systems and sea-level
rise
• Marine fisheries
• Tropical coral reefs
Example: Amazon dieback
• Forest dieback – ‘flipping’
to savannah and semidesert, uneven effects
across the region
• Climate-vegetation
feedbacks – climate
change + deforestation =
drying + fires
• ‘Important’ changes by
2025, ‘flip’ by 2050?
Local biodiversity tipping points
Can occur through, e.g.
• Loss of specific species (framework species,
ecological engineers);
• Loss of trophic levels (e.g. large predators);
• Loss of communities (e.g. through pollution,
disease)(Dobson et. al. 2006)
Local-global synergies
• Global state shifts: global forcings or many smallerscale events originating in local systems?
• Past global state shifts all related to global scale
forcings that modified oceans, atmosphere, and
climate
• Known that ‘local-scale state changes…trigger critical
transitions over larger regions.’
• If enough systems transform, the rest may change
rapidly, ‘especially because emergent, larger-scale
forcings…multiply and interact to exacerbate local
forcings’ (Barnosky et. al. 2012).
Humans are keystone species across 77% of
terrestrial ice-free area (Ellis & Ramankutty 2008)
‘Human societies have been built on
biodiversity’ (Díaz et. al. 2006
• The human ‘project’ is to alter the environment – humans
organise socially to alter the environment to meet sociallydefined needs
• Human-nature co-evolution: humans are keystone species
and environments shape culture
• Humans create tipping points – e.g. urbanisation,
hydrological engineering, deforestation/intensive agriculture
• The type/degree of environmental transformation depends
fundamentally on the ‘rules’ of the mode of
production/subsistence - not all societies degrade the
environment or over-exploit resources
Today’s highly biodiversity-dependent
and highly adaptive societies
•
of the world’s population…40% subsists to a large degree
from agriculture, which occupies 40% of terrestrial ice-free
area
•
90% of farmers cultivate 2 ha. or less; at least 50% is
‘traditional’ - usually biodiversity-rich polycultures
•
250 million live largely from forests, and 60 million indigenous
people live exclusively from forests
•
50 million depend on small-scale fisheries
•
1 billion regularly consume wild food
•
1.3 billion live from ‘environmentally fragile’ lands where
environmental disturbances and disequilibria rule
Different social formations/environmental
relations/resilience
• Cultural evolution (e.g. Richarson & Boyd 2005) – has allowed
humans to adapt to every type of environment on Earth
• Institutions (means of production & exchange, knowledge,
technology and innovation) have evolved in part in function
of environmental disequilbria and disturbance
• Often are low or no external input, biodiverse, knowledgeintensive, with social rules and religious beliefs that regulate
resource access and use
• Resilience based on institutionalised adaptive capacity, but
this is generally ignored by outsiders
Humans are highly adaptive to
environmental change
Historically a range of pathways to adapt to biodiversity
and other environmental change (Thornton and Manasfi 2010):
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Mobility (e.g. habitat tracking, migration)
Exchange (e.g. biological trade corridors)
Rationing (e.g. through ritual redistribution)
Pooling (e.g. of decimated herds)
Diversification (e.g. camel pastoralists begin to fish)
Intensification (e.g. using greater labour inputs)
Innovation (e.g. changing technology)
Conservation (e.g. creating ecological niches)
Revitalization (e.g. regenerating
conservation/management values, limits to
accumulation)
Sahrawi nomads’ adaptation (Volpato 2012)
Types of biological outcomes that may
lead to SES tipping points
• Loss of communities – e.g. forest to savannah as in Amazon
dieback, deforestation
•
Loss (or loss of productivity) of cultural keystone species (camels,
eagles, herring, sago palm, etc.)
•
Loss (or loss of productivity) of other functionally non-redundant
species (culturally, economically, ecologically) or trophic levels (e.g.
large fish)
•
Gain of negative species (e.g. elephants, poisonous plants, diseasebearing organisms)
Vulnerability to biodiversity change
•
Exposure and physical susceptibility (e.g. degree of
dependence on species and services that species
provide – greater in arid areas, islands, Arctic,
coasts)
•
Breakdown of institutional resilience (loss of
knowledge and skills, institutional means of sharing
and reconstituting resource base)
•
Social, economic, and ecological fragilities
presented by modern institutions and power relations
•
Loss of languages and cultures – faster than the
current rate of species loss
Modern limits to adaptation or,
moving toward collapse?
• Prior occupation and other restrictions on movements:
borders, nationalism, prior access rights to land, forests,
etc., prohibit e.g. habitat tracking, migration
• Profit criteria determine resource allocation and use (e.g.
land grabs for biofuels or food production)
• Power relations (economic but also political) determine
who is able to do what with what; who pays costs and
who reaps benefits
• Limits on collective action – e.g. on what the State and
other public institutions can do vis a vis private interests
• Knowledge – scientific knowledge is imprecise; local
Ruminations
• Crossing biodiversity tipping points is nearly inevitable;
•
We need lots of alternatives for adaptation and generating new
stable states - a) institutional arrangements, b) economic
relations, c) human-nature relations, and d) knowledge and
information, and these must be locally adapted;
• Thus, we need evolved planetary cultural resilience in the form
of biocultural diversity but we are losing it more rapidly than
we are losing species;
• We know almost nothing about things that we need to know a
great deal about, and lack the wisdom to know it