Ortiz

Agricultural Knowledge, Science and Technology for Development (IAASTD)

R. Ortiz

Introduction

The world faces an increasing demand for its fi nite resources. There will be 1.7 billion more people to feed by 2030, but with a declining ratio of arable land between 40% and 55%

and about 1.8 billion people living under water scarcity (CropLife International, 2009).

Furthermore, a recent scenario analysis suggests that on average about 3000 kcal per capita daily will need to be available world-wide in 2050 to feed the growing human population (Hubert et al., 2010). This goal may be seen as att ainable but the world in the mid-21st century will be facing water shortages, fl ooding and global warming as a result of climate change (Baetghen, 2009).

Increasingly, more wealthy and healthy people will demand greater dietary diversity in a global bio-based economy. Global economic growth and sustainable intensifi cation of crop–livestock agroecosystems remain there-fore as major challenges for feeding this grow-ing human population. In this regard, today’s farming worldwide needs high yielding crops that can grow more effi ciently, such as those requiring less inputs or adapting to water and heat stresses or new epidemics of emerging pests at a time of global climate change.

In this chapter, innovations on agro-biodiversity management that reduce vul-nerability to climate change (e.g. mitigation

through management and adaptation through the genetic improvement of resilient and climate-proof crops) are considered in detail.

Such innovations will greatly assist in addressing these challenges and will ensure enough food, feed, fi bre and biofuel supply in the next decades. Furthermore, learning from today’s agrobiodiversity management that buff ers crops and cropping systems against annual extreme weather variations could help to improve their adaptation to future climate.

Nelson et al. (2009) argued recently that crops and livestock that perform reasonably well in a range of production environments are needed rather than those doing extremely well in a narrow set of climates. And, as indicated by Challinor et al. (2007), crop cultivars should adapt to both means and extremes of temperature stresses under climate change.

Climate Change Impacts on Agrobiodiversity and Food Security Global yield losses due to global warming have amounted to 40 million t or US$5 billion yearly for wheat, maize and barley since 1981 (Lobell and Field, 2007). Furthermore, crop modelling shows that climate change will continue to reduce agricultural production, thus reducing food availability and thereby

aff ecting food security and farm incomes (Schmidhuber and Tubiello, 2007; Lobell et al., 2008; Batt isti and Naylor, 2009). The Intergovernmental Panel on Climate Change in its 4th Assessment Report confi rms that indeed changing climate will bring a high intensity and frequency of storms, drought and fl ooding, weather extremes, altered hydrological cycles and precipitation, which, without doubt, will aff ect agricultural production. These impacts will depend on region, growing season, weather patt erns and crops. For example, severe crop losses are expected for cott on, maize and soybean in the USA by the end of this century due to warmer temperatures (Schlenker and Roberts, 2009).

Grain harvests in China and South Asia may also drop by 37% and 30%, respectively, by 2050 due to weather extremes, whereas extreme drought (i.e. doubling severity and frequency) in north-east China could result in 12% crop losses (or 13.8 million t) by 2030 (Bloomberg News, 2009). Although models provide an important tool for understanding and assessing future climate impacts, results from modelling should be taken with caution because their spatial scales could fail to capture topographical or microclimatic buf-fering, and they do not oft en consider the wide acclimation capacity of animals and plants (Willis and Bhagwat, 2009). Hence, as stated by Tubiello et al. (2007), understanding the key dynamics characterizing interactions between elevated CO₂ and changes in climate variables (e.g. extremes, soil and water quality, pests, pathogens) and ecosystem vulnerability remains as priority research for quantifying bett er the impacts of climate change on crops and pastures.

Changes in climate could also rapidly shift plant distributions because some species will expand in newly favourable areas and others will decline in increasingly adverse locations (Kelly and Goulden, 2008). For example, models suggest that at least 50% of the plant species in Europe could be vulnerable or threatened by 2080 (Thuiller et al., 2005). In this regard, Lane and Jarvis (2007) using the Ecocrop model (htt p://

ecocrop.fao.org) projected the impact of climate change by 2055 on suitable areas for

most important staples and cash crops, including those of the multilateral system of the International Treaty on Plant Genetic Resources for Food and Agriculture. The largest gain in suitable areas is likely to be in Europe (3.7%) whereas sub-Saharan Africa and the Caribbean may suff er 2.6% and 2.2%

declines of land area, respectively. Although their modelling suggests some crop gains in suitable areas (e.g. 31% for pearl millet, 18%

for sunfl ower, 15% for chickpea and 14% for soybean), these ‘new crop lands’ are in regions where they are not important local food staples, e.g. 10% increase for pearl millet in Europe and the Caribbean rather than in sub-Saharan Africa and India.

As this chapter will show, agrobio-diversity remains the main raw material for agroecosystems to cope with climate change because it can provide traits for plant breeders and farmers to select resilient, climate-ready crop germplasm and release new cultivars.

However, modelling research suggests that some crop wild relatives may become extinct by 2055 (Jarvis et al., 2008), e.g. 8% of Vigna, 12% of tuber-bearing Solanum and 61% of Arachis species. Collecting samples of en-dangered species to be preserved in genebanks will be the fi rst step, but also protecting the habitats where they thrive should be a must to ensure the in situ evolutionary processes of wild species contributing to agrobiodiversity.

Furthermore, as noted by recent research of maize, pearl millet and sorghum genetic resources in sub-Saharan Africa (Burke et al., 2009), available genetic resources for these crops in genebanks may not be the most useful for adapting them to climate change in this continent. Hence, analogue crop areas for many future climates should be promising locations to focus future collecting and conserving of crop genetic resources.

Inter-governmental Panel on Climate Change (IPCC) and Agrobiodiversity

Management

Although the world can cope with climate change by maintaining and using agro-biodiversity, IPCC has not given enough

att ention to the value of biodiversity for food and agriculture, which will increase with global warming, drought and other stresses.

The chapter on agriculture of the 4th IPPC Assessment (Metz et al., 2007) does not mention agrobiodiversity (or refer properly to agricultural biodiversity) and how it can contribute to climate change adaptation.

There are, in this and other chapters, a few references to biodiversity at large and mostly related to mitigation or losses brought by climate change, particularly in forests or the soil biota. However, agrobiodiversity main-tenance through use plays an important role for climate change adaptation. In the past, crop and livestock diversity has traditionally been an important part of farmer risk management. An increase of agrobio diversity use is further expected and necessary as a result of climate change.

Agrobiodiversity at the gene, species and agroecosystem levels increases resilience to the changing climate. Promoting agrobio-diversity remains therefore crucial for local adaptation and resilience of agroecosystems (FAO Interdepartmental Working Group on Climate Change and the Stockholm Environ-ment Institute, 2007). Adapting agriculture to climate change will indeed rely on matching crop cultivars to future climates and plant breeding for coping both with climate variability and extremes, but also on pro-moting farmer resilience and adaptability.

Hence, agrobiodiversity is not a victim of climate change but provides the raw resource for adapting to this global challenge.

The United Nations Environment Programme considers that breeding stress-resistant crop cultivars, along with provision of crop and livestock insurance, social safety nets, new irrigation schemes and local management form the core of short-term responses for adapting to climate change (UNEP, 2008). Likewise, local agrobiodiversity is an important coping mechanism, especially for most vulnerable people. However, the locally available agrobiodiversity in some areas may not be able to adapt quickly to the changing climates. Hence, new crop cultivars, livestock breeds or other species bett er suited to these new environments will be needed to cope with climate change.

Coping with Climate Change through Knowledge-base Agricultural Research

Answers

Howden et al. (2007) advocate a multi-disciplinary approach to address climate change. This integrated rather than disciplin-ary approach also considers strengthening the interface with decision makers. Recently, the Food and Agriculture Organization of the United Nations provided a summary of potential changes in agroecosystems that have been proposed to increase agricultural production, as well as to decrease output variability due to climate variability and extreme climate events (FAO, 2009). The suggested options advocate an adaptation approach to climate change focusing on an increase in agroecosystem resilience that reduces the impacts brought by extreme climate events on food supply. In this regard, any adaptation strategy should aim to minimize the agroecosystem’s vulnerability to climate change. Adapting agriculture to climate change will depend on the aff ordability of the adaptive measurements, technology access and biophysical characteristics (land and water availability, soil, topography) and useful agrobiodiversity for crop and livestock breeding.

Cropland management for climate change Sustainable land management involves changes that increase natural capital and reduce negative environmental impacts, and off ers a means for mitigating climate change through carbon sequestration in soils and biomass, as well as reducing emissions from degradation and inappropriate farming practices (Various, 2008). New cultivars, con-servation agriculture practices (e.g. minimum tillage) and increased input effi ciency are among those adaptation options for cropland management (Reynolds and Ortiz, 2010).

Conservation agriculture can increase soil organic carbon, thereby improving soil fertility, and also helps to sequester carbon in agricultural soils. Crop breeding (including modern biotechnology such as genomics and transgenics) provides genetically enhanced