Measures to promote both mitigation and adaptation to climate change in agriculture Jørgen E. Olesen

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 (CO 2, CH 4, N 2 O) - Climate change impacts - Soil quality - Water usage - Resilience to climatic variability - Adaptation to climate change

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 % of global greenhouse gas emissions

Proportion of heavy rainfall has increased most places Regions of disproportionate changes in heavy (95% fractile) and very heavy (99% fractile) precipitation. IPCC WG-I (2007)

Observed changes – increasing droughts (1990 – 2002) IPCC WG-I (2007)

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

Soil degradation Erosion Reduction i soil carbon (humus) Compaction (especially in subsoil) Pollution Salinisation Desertification Many of these processes are exacerbated by climate change

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

Suitability for rainfed cereal production IIASA

Change in suitability for rainfed grain 2080 IIASA Consequence of - Temperature increases changing suitability for production - Rainfall changes (dry areas becoming drier) Does not account for changes in variability and extremes

Crop yield response to temperature change IPCC WG-II (2007) Without adaptation With adaptation

Temperature changes PRUDENCE Winter temperature ( ) – ( ) Summer temperature ( ) – ( )

Precipitation changes PRUDENCE Winter rainfall (% change) ( ) – ( ) Summer rainfall (% change) ( ) – ( )

Increased variability PRUDENCE Winter Summer PrecipitationTemperature

The 2003 summer heat wave in Europe 30% reduction in gross primary production of terrestrial ecosystems Large reductions in agricultural production (13 billion €) Many very large wildfires Large CO 2 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) MODIS data

Observed and projected temperature i Central Europe Schär et al. (2004)

Drought effects on vegetation in France Sequin based on SPOT

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!!

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

 Generally increasing temperatures  Increasing rainfall intensity  More frequent droughts  More variable climate (in many areas) Agriculture must adapt to climate change --- This requires ---  Higher resilience to climatic variability  Better use and management of water And can be achieved through ---  Maintaining fertile soils with high water holding capacity  Improving crop genotypes (drought tolerance)  Diversifying crop rotations and cropping systems  Cover crops and intercrops to improve fertility/retain nutrients  Adapting crop management to increase resilience to change

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

Nitrous oxide emissions (N 2 O) N 2 O originates from both nitrification og denitrification N 2 O 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 NH 3 NO 2 N2ON2O NO 3 N2N2 Nitrification (aerobic) Denitrification (anaerobic) Nitrifications inhibitors Plant uptake

Nitrous oxide from direct sowing (DS) relative to ploughed (PL) Soil aeration poormedium good N 2 O DS:PL Rochette et al. (2008) based on review of many studies

Soil tillage effects on N 2 O emissions Harrowing 8-10 cmPloughingDirect drilling N O-N kg/ha 2 Straw removed Straw left Mutegi and Munkholm, AU-DJF

Relative diffusivitet (x10 3 ) Aeration and N 2 O emissions R 2 = 0.52 Increased aeration Mutegi and Munkholm, AU-DJF

Effect of catch crops C-input  Difference between species  C-storage in depth C-turnover  Turnover of C-input from both top and roots N 2 O emissions  Effect? Oil radish Foto: Ole Green

Mitigation and adaptation synergies PICCMAT

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 N 2 O 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

Smart solutions involve both adaptation and mitigation