Measures to promote both mitigation and adaptation to climate change in agriculture

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Measures to promote both mitigation and
adaptation to climate change in agriculture

• Jørgen E. Olesen

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Agriculture and climate change

• Agriculture is highly integrated into the climate
  change challenge
• Agriculture is one of the main emitters of
  greenhouse gases
• Agriculture is highly impacted by climate change
  (temperature, rainfall)
• Issues
• GHG emissions (CO2, CH4, N2O)
• Climate change impacts
• Soil quality
• Water usage
• Resilience to climatic variability
• Adaptation to climate change

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The challenge of a growing world population

• The world population is increasing and will peak
  at about 9-10 billion (from currently 6 billion).
• Increasing wealth causes changes in lifestyle
  towards more meat and milk in the diet and in
  the longer term for higher quality foods
• The global livestock production is increasing
  rapidly (meat production will double from 2000 to
  2050)
• World grain production also has to double by 2050
• Agriculture accounts for 20-30 of global
  greenhouse gas emissions

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Proportion of heavy rainfall has increased
mostplaces
Regions of disproportionate changes in heavy (95
fractile) and very heavy (99 fractile)
precipitation.
IPCC WG-I (2007)
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Observed changes increasing droughts (1990
2002)
IPCC WG-I (2007)
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Drylands

• 10-20 of drylands are subject to degradation
• Dryland populations are among the most
  ecologically, socially and politically
  marginalised populations

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Soil degradation

• Erosion
• Reduction i soil carbon (humus)
• Compaction (especially in subsoil)
• Pollution
• Salinisation
• Desertification

Many of these processes are exacerbated
by climate change
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Pressure on freshwater resources

• 14 of world agricultural area is irrigation
• 40 of agricultural production comes from
  irrigated agriculture
• 80 of freshwater abstraction is used for
  irrigation
• Increasing problems with drying out and pollution
  of rivers and lakes

Water consumption for irrigation
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Suitability for rainfed cereal production 1961-90
IIASA
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Change in suitability for rainfed grain 2080
Consequence of - Temperature increases changing
suitability for production - Rainfall changes
(dry areas becoming drier) Does not account for
changes in variability and extremes
IIASA
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Crop yield response to temperature change
Without adaptation With adaptation
IPCC WG-II (2007)
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Temperature changes
Winter temperature (2071-2100) (1961-1990)
Summer temperature (2071-2100) (1961-1990)
PRUDENCE
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Precipitation changes
Winter rainfall ( change) (2071-2100)
(1961-1990)
Summer rainfall ( change) (2071-2100)
(1961-1990)
PRUDENCE
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Increased variability
Precipitation
Temperature
Winter
Summer
PRUDENCE
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The 2003 summer heat wave in Europe
MODIS data
30 reduction in gross primary production of
terrestrial ecosystems Large reductions in
agricultural production (13 billion ) Many
very large wildfires Large CO2 emissions from
soils Record low river flows affecting
ecosystems, navigation and cooling of power
plants Reduction of 10 transportation capacity
on the Rhine (200 mil. ) Extreme glacier melt in
the Alps prevented extremely low flows in the
Danube river Excess deaths due to very hot
temperatures (about 35,000)
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Observed and projected temperature i Central
Europe
Schär et al. (2004)
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Drought effects on vegetation in France
2006
2003
2005
Sequin based on SPOT
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Is expanding irrigation a solution?

• Irrigation is efficient for limiting yield
  losses, but..
• - restricted to a small part of the area
• - higher water comsumption in dry years
• - increasing competition with other uses
• so that the increasing the extent of
  surfaces for irrigation is questionable in the
  context of diminishing water resources!!

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We need to increase water use efficiency

• Efficiency of irrigation systems (more crop per
  drop)
• Trickle irrigation systems to target crop demand
  and avoid evaporation
• Irrigation systems that induce partial stomatal
  closure
• Water harvesting systems (avoiding excessive
  runoff)
• Increasing soil water retention (soil structure,
  organic matter)
• Avoiding soil evaporation (e.g. through mulching)
• Drought tolerant crop species and cultivars
• Combinations of these measures are needed!!!
• Most of these measures also promote soil carbon
  storage

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Agriculture must adapt to climate change ---

• Generally increasing temperatures
• Increasing rainfall intensity
• More frequent droughts
• More variable climate (in many areas)

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Faktors affecting soil carbon content
Carbon-input (amount and quality) (plant
residues, manure) Turnover rate (soil
moisture, temperature, tillage) Other
losses (erosion)
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Nitrous oxide emissions (N2O)

• N2O originates from both nitrification og
  denitrification
• N2O is formed under suboptimal conditions for the
  micro organisms (e.g. low oxygen or low pH) or in
  transfer zones between aerobic and anaerobic
  sites.
• Often associated with over-fertilisation or bad
  timing of fertilisation

N2
N2O
Denitrification (anaerobic)
NO2
NH3
NO3
Plant uptake
Nitrification (aerobic)
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Nitrous oxide from direct sowing (DS) relative to
ploughed (PL)
N2O DSPL
poor
medium
good
Soil aeration
Rochette et al. (2008) based on review of many
studies
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Soil tillage effects on N2O emissions
Mutegi and Munkholm, AU-DJF
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Aeration and N2O emissions
R2 0.52
Increased aeration
Relative diffusivitet (x103)
Mutegi and Munkholm, AU-DJF
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Effect of catch crops
Oil radish

• C-input
• Difference between species
• C-storage in depth
• C-turnover
• Turnover of C-input from both top and roots
• N2O emissions
• Effect?

Foto Ole Green
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Mitigation and adaptation synergies
PICCMAT
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Agricultural production systems that promote both
adaptation and mitigation

• More permanent crop cover and less intensive soil
  tillage
• Perennial crops to sequester carbon and reduce
  N2O emissions
• Combine bioenergy and feed (food) production
• Highly productive vegetative (perennial) crops
• Biomass is treated in biorefineries to produce
  energy and feed
• Highly efficient nutrient use during production
  and processing
• Diversity to improve resilience and increase
  carbon capture
• Cropping systems with improved water use
  efficiency
• Renewed focus on agricultural research and
  innovation is needed

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Smart solutions involve both adaptation and
mitigation