Transcript Desertification - Durham University

Desertification
Issue since the 70’s
Basis of UN conference in 1977 (UNCOD)
Aim to eradicate it by 2000!!
Since viewed as one of most pressing
issues affecting human kind
Desertification
“Land degradation in arid, semi-arid and dry
sub-humid areas, resulting from various
factors including climatic variability and
human activities”
UNEP 1992
Desertification
“An acute process that occurs at rates
several orders of magnitude faster than
purely climatically driven land responses.”
Thornes, 1996
Land
“terrestrial bio-productive system that
comprises the soil, vegetation, other biota
and ecological and hydrological processes
that operate within the system”
Land Degradation
“reduction or loss of the biological or
economic productivity caused by land use
change, from a physical process, or a
combination of the two”
Problems
Adopting a definition
Taken 20 years
Human influence
Conditions
Cause
Processes
Causes
Triggered by changes in climate and
socio-economic boundary conditions of
dryland systems
Enters +ve feedback of over exploitation
of the land
Results in land degradation and disruption
of local economies
Dryland characteristics
High incident radiation
high seasonal temperature variations
low humidity
strong winds
intense and sporadic rainfall
i.e. a delicate hydrological balance
Triggers
Overgrazing
deforestation
precarious agriculture
uncertain rainfall
river flooding
depletion of surface water
depletion of ground water
That is:
Anything that unbalances dryland systems
In the long term
Includes expansion of settlement at the
cost of cultivatable land
Extent
Determined by:
rainfall patterns
soil morphology
soil pedology
vegetation
land use
Water
A main limiting factor re production and
settlement
A fundamental cause of Desn
Areas have potential for water
development
lack integrated water management policy
Areas of research
Assess the nature and extent of the
problem
Identify physical processes
Identify remedial actions
Investigate the reln to other environmental
problems
The human dimension
The Human Dimension
Scientists seen in a -ve light because of:
1) Speed of research relative to societal
problems
2) Nature of scientific findings
3) Manner in which scientific research
develops
Science and Society
No instant solutions
Time periods
Reln between drought and desertification
Nature of findings
Desn complex and multifaceted
Diversity of drylands
Solutions non transferable
Scientists viewed as not doing anything
Nature of Research
Findings not definite and final
iterative development
new sources of data, new technology,
more research results in paradigm shift
Scientist’s Role
Establish and retain clarity
Monitoring
Understand scales
System recovery
Solutions
Need involvement of everybody
farmers, pastoralists, national resource users,
international, governments etc
Traditional science not producing results
Need community action and indigenous
knowledge
Namibia
824 000 km2
Driest country of Sahel
34% arid, 58% semi-arid, 8% sub-humid
1.6 million popn
No perennial rivers
47% land owned by white, commercial
farmers
48% communal farmers, 90% of popn
SDP - Summer Desertification Programme
use of natural resources, changes, solutions
CBNRM - Sustainable Animal and Range
Development Programme
livestock and communal farming
NAPCOD - Namibian Programme to
Combat Desertification
Ministries, NGO, community workshops
All fairly successful
All had community participation and local
knowledge
Constrained at national level
Need overall planning. Policy and
legislative framework
Europe
Tertiary - climate transition to summer
drought
Evolved under stress of changing
geological and climatic conditions
Holocene - consolidated dry periods
N-S aridity gradient getting steeper last
5000 years