Climate change as a driver of agricultural change

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Climate change as a driver of agricultural change

• Andrew Watkinson
• University of East Anglia

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Climate is Changing
Warming of the climate system is unequivocal, as
is now evident from observations of increases in
global average air (and ocean) temperatures,
widespread melting of snow and ice, and rising
global average sea level (IPCC WG1 AR4)
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Physical Biological
Global
Source IPCC AR4
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Responses on agriculture and forestry

• Responses to recent climate changes in human
  systems are difficult to identify due to multiple
  non-climate driving forces and the presence of
  adaptation
• In comparison with other factors, recent warming
  has been of limited consequence in agriculture
  and forestry.
• A significant advance in phenology has been
  observed for agriculture and forestry in large
  parts of the Northern Hemisphere, with limited
  responses in crop management.
• Both agriculture and forestry have shown
  vulnerability to recent trends in heatwaves,
  droughts and floods

IPCC WG2 Ch 1, 2007
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Phenology

• Changes are apparent in perennial crops, such as
  fruit trees and wine-making varieties of grapes,
  which are less dependent on yearly management
  decisions by farmers than annual crops and are
  also often easier to observe.
• Phenological changes are often observed in tandem
  with changes in management practices by farmers.
• Between 1951 and 2004 the advance for
  agricultural crops (2.1 days/decade) in Germany
  has been significantly less marked than for wild
  plants or fruit trees (4.4 to 7.1 days/decade).

Frequency
Trend (days/year)
Menzel et al. 2006
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Weather and harvest
Source Tim Sparks
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2003 Heat wave

• Temperatures were up to 6C above long-term means
• Precipitation deficits were up to 300 mm
• Yields were typically 30-36 lower for maize,
  fruit crops and forage in parts of Italy and
  France
• Wine production in Europe was the lowest in 10
  years
• Winter crops (wheat), which had nearly achieved
  maturity by the time of the heatwave, suffered
  less yield reduction (21 decline in France) than
  summer crops (e.g. maize) undergoing maximum
  foliar development
• The (uninsured) economic losses were estimated at
  13 billion for the agriculture sector in the
  European Union, with largest losses in France
  (4billion)

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Climate change and yield
Little detectable change

• Europe
• No detectable change in crop yield directly
  attributable to climate change
• the yield trend of winter wheat displays
  progressive growth from 2.0 t/ha in 1961 to 5.0
  t/ha in 2000, with anomalies due to climate
  variability on the order of 0.2 t/ha
• An increase in summer temperatures has led to
  decline in hay yield in the UK (1C increase in
  July-August led to a 0.33 t/ha loss)
• Asia
• rice production in India has grown from 20 Mt in
  1950 to over 90 Mt in 1999, with only a slight
  decline during El Nino years when monsoon
  rainfall is reduced
• negative effect of warming on rice production in
  the Philippines (yield loss of 15 for 1C
  increase of growing-season minimum temperature in
  the dry season) is limited to a local observation
  for a short time period
• North America
• Maize and soybean yields in the USA are higher in
  cooler and wetter years in the Midwest and hotter
  and drier years in the North-west plains.
• Africa
• In the Sahel, warmer and drier conditions have
  served as a catalyst for a number of other
  factors that have accelerated a decline in
  groundnut production

IPCC WG2 Ch1, 2007
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Projections of Future Changes in Climate
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Precipitation
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Predicted change in crop yields
To what degree will crop yields decrease in the
tropics and sub-tropics, but increase at high
latitudes?
Percentage change in average crop yields for a
mid-range climate change scenario Even as soon
as 2020 crop yields in SSA and parts of Asia are
projected to decrease by up to 20
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Projected impacts by sector
Source IPCC WG2, 2007
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Climate impacts the imperative for adaptation
and mitigation
Source Parry et al 2008
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Cereal prices under climate change?
IPCC WG2 Ch 5, 2007
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UK projections mean temperature change
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Mean precipitation change
2080s Summer
2080s Winter
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Impacts on Farming and Land Use

• Extended growing season
• But fewer work days with machinery (depends on
  soil wetness)
• New crops possible
• Increased need for irrigation
• Mixed effects on pests/disease
• Effects on land use and landscape
• Effects on wildlife
• Farming responds to energy policies
• e.g. Biofuels/Wind-farms

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Crop zones will move northwardsSuitability for
grain maize, sunflower and soya, 2050s
red/brown/blue suitability extension green/yellow
/purple Baseline 1961-90
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Global agriculture and food security
Global Population
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Climate Change Risks, opportunities and
responsibilities

• Farmers are among the first to feel the impact
  of a changing climate and need to adapt to it.
• Climate change brings
• Risks
• Opportunities
• Responsibilities
• for farmers and land managers

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Risks from

• Reduced soil moisture
• Increased heat stress in livestock
• Greater variability in crop yield due to more
  extreme and variable weather
• New pests and diseases in previously safe
  areas e.g. spread of Bluetongue disease to UK
  which until 2006 was only found in southern
  Europe (and Africa)
• Warmer temperatures which will allow
  over-wintering of pests and diseases, leading to
  larger populations
• Flooding due to wetter winters and more extreme
  events
• More frequent storms, and storm damage
• Drought due to drier summers
• Increased soil erosion
• Water pollution from increased runoff.
• Unplanned responses to climate change that have a
  knock on impact on other aspects of agricultural
  ecosystems?
• New export opportunities?
• Increased intensification on marginal land?
• Effect of new crops/techniques on environment /
  biodiversity?
• Impact of biofuels?

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Opportunities to

• Benefit from longer growing seasons 1-3ºC
  increasing crop yields extended geographic range
  of crops reduced frost damage to crops reduced
  energy costs (e.g. for drying grain)
• Introduce new or novel crops and livestock
  species e.g. new crops already being grown in
  the UK, including olives (Devon) and apricots
• Produce crops and biomass to displace fossil fuel
  energy
• Or a broader range of oilseeds, vines, and energy
  crops
• Or use anaerobic digestion to produce biogas
• Provide more sustainable materials e.g. for
  construction
• Provide carbon sinks for greenhouse gas
  emissions from other sectors of the economy

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Responsibilities to

• Reduce direct emissions of methane, nitrous
  oxide, and carbon dioxide e.g.
• Matching fertiliser to crop need (precision
  farming)
• Spreading manure at appropriate times and in
  appropriate conditions
• Improving dairy yields
• Changes to livestock diets (e.g. maize silage
  rather than grass silage)
• Using anaerobic digestion for manure and slurry
• Ensuring on-farm energy efficiency or use of
  renewables
• Protect carbon stores in soils, peat and woodland
  Protect biodiversity and habitats
• Manage water sustainably
• Emphasise role of whole ecosystem in dealing with
  change well-managed ecosystems reduce risks and
  vulnerability, poorly managed ecosystems can
  exacerbate them

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Adaptation to Climate Change

• The response of agricultural, pastoral and forest
  systems to simultaneous changes in atmospheric
  and climatic parameters
• carbon dioxide -- are there saturation effects,
  if so at what concentration level
• mean temperature and its variability (day-night
  and summer-winter ratios)
• mean precipitation and its variability
• other factors, including tropospheric ozone, UV-B
  and acid deposition
• The impact of changes in climate and atmospheric
  composition on
• disturbance regimes, including fires and pest and
  disease outbreaks
• Adaptation options
• planting times
• crop selection
• irrigation
• fertilization
• new cultivars -- the role of biotechnology,
  including transgenic crops temperature,
  drought, pest and salinity tolerance

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Climate change impacts on maize and wheat yields
With adaptation
Without adaptation
Source IPCC WG2 Ch5, 2007
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Mitigation
77 CO2
14 CH4
Agriculture 13.5
8 N2O
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Mitigation and BiofuelsCan Biofuels be
Economically, Environmentally and Socially
Sustainable?

• Two major sources of biofuels
• Bioethanol from sugar and maize
• Biodiesel from palm oil, soy and rapeseed
• Rarely economic - normally heavily subsidized
• Serious questions regarding environmental
  sustainability
• Greenhouse gas emissions - direct and indirect
  emissions
• Loss of biodiversity, soil and water degradation
• Serious Questions regarding social sustainability
• Competition for land - food price increases
• Involuntary displacement of small-scale farmers
  by large-scale plantations

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Adaptation and mitigation in a multi-functional
landscape
Biodiversity
Employment
Biomass
Energy
Clean water
Recreation
Food
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The evolving agricultural landscape
2005
2020

• Greater connectivity
• Biomass crops
• Integrated catchment management
• Access
• Nitrogen and phosphate sensitive areas

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Climate change and Agriculture

• Climate change will fundamentally alter the
  structure of the landscape
• Agriculture has a role to play in climate
  mitigation
• Recognize that the agricultural sector will have
  to adapt to a changing climate with opportunities
  and challenges
• Recognize that agriculture is multi-functional