Evan D.G. Fraser

Crops and climate change: progress, trends, and challenges in simulating impacts and informing adaptation

Assessments of the relationships between crop productivity and climate change rely upon a combination of modelling and measurement. As part of this review, this relationship is discussed in the context of crop and climate simulation. Methods for linking these two types of models are reviewed, with a primary focus on large-area crop modelling techniques. Recent progress in simulating the impacts of climate change on crops is presented, and the application of these methods to the exploration of adaptation options is discussed. Specific advances include ensemble simulations and improved understanding of biophysical processes. Finally, the challenges associated with impacts and adaptation research are discussed. It is argued that the generation of knowledge for policy and adaptation should be based not only on syntheses of published studies, but also on a more synergistic and holistic research framework that includes: (i) reliable quantification of uncertainty; (ii) techniques for combining diverse modelling approaches and observations that focus on fundamental processes; and (iii) judicious choice and calibration of models, including simulation at appropriate levels of complexity that accounts for the principal drivers of crop productivity, which may well include both biophysical and socio-economic factors. It is argued that such a framework will lead to reliable methods for linking simulation to real-world adaptation options, thus making practical use of the huge global effort to understand and predict climate change.

Anticipating Vulnerability to Climate Change in Dryland Pastoral Systems: Using Dynamic Systems Models for the Kalahari

It is vitally important to identify agroecosystems that may cease functioning because of changing climate or land degradation. However, identifying such systems is confounded on both conceptual and methodological grounds, especially in systems that are moving toward thresholds, a common trait of dryland environments. This study explores these challenges by analyzing how a range of external pressures affect the vulnerability of dryland pastoral systems in the Kalahari. This is achieved by employing dynamic systems modeling approaches to understand the pathways by which communities became vulnerable to drought. Specifically, we evaluate how external pressures have changed: (1) different agroecosystems abilities to tolerate drought, i.e., ecosystem resilience; (2) rural communities abilities to adapt to drought, mediated via their access to assets; and (3) the ability of institutions and policy interventions to play a role in mediating drought-related crises, i.e., socio-political governance. This is done by reanalyzing ecological and participatory research findings along with farm-scale livestock offtake data from across the Kalahari in Botswana. An iterative process was followed to establish narratives exploring how external drivers led to changes in agroecosystem resilience, access to assets, and the institutional capacity to buffer the system. We use causal loop diagrams and statistical dynamic system models to express key quantitative relationships and establish future scenarios to help define where uncertainties lie by showing where the system is most sensitive to change. We highlight how that greater sharing of land management knowledge and practices between private and communal land managers can provide win-win-win benefits of reducing system vulnerability, increasing economic income, and building social capital. We use future scenario analyses to identify key areas for future studies of climate change adaptation across the Kalahari.

Assessing Vulnerability to Climate Change in Dryland Livelihood Systems: Conceptual Challenges and Interdisciplinary Solutions

Over 40% of the earths land surface are drylands that are home to approximately 2.5 billion people. Livelihood sustainability in drylands is threatened by a complex and interrelated range of social, economic, political, and environmental changes that present significant challenges to researchers, policy makers, and, above all, rural land users. Dynamic ecological and environmental change models suggest that climate change induced drought events may push dryland systems to cross biophysical thresholds, causing a long-term drop in agricultural productivity. Therefore, research is needed to explore how development strategies and other socioeconomic changes help livelihoods become more resilient and robust at a time of growing climatic risk and uncertainty. As a result, the overarching goal of this special feature is to conduct a structured comparison of how livelihood systems in different dryland regions are affected by drought, thereby making methodological, empirical, and theoretical contributions to our understanding of how these types of social-ecological systems may be vulnerable to climate change. In introducing these issues, the purpose of this editorial is to provide an overview of the two main intellectual challenges of this work, namely: (1) how to conceptualize vulnerability to climate change in coupled social-ecological systems; and (2) the methodological challenges of anticipating trends in vulnerability in dynamic environments.

Increased crop failure due to climate change: assessing adaptation options using models and socio-economic data for wheat in China

Tools for projecting crop productivity under a range of conditions, and assessing adaptation options, are an important part of the endeavour to prioritize investment in adaptation. We present ensemble projections of crop productivity that account for biophysical processes, inherent uncertainty and adaptation, using spring wheat in Northeast China as a case study. A parallel ‘vulnerability index’ approach uses quantitative socio-economic data to account for autonomous farmer adaptation. The simulations show crop failure rates increasing under climate change, due to increasing extremes of both heat and water stress. Crop failure rates increase with mean temperature, with increases in maximum failure rates being greater than those in median failure rates. The results suggest that significant adaptation is possible through either socio-economic measures such as greater investment, or biophysical measures such as drought or heat tolerance in crops. The results also show that adaptation becomes increasingly necessitated as mean temperature and the associated number of extremes rise. The results, and the limitations of this study, also suggest directions for research for linking climate and crop models, socio-economic analyses and crop variety trial data in order to prioritize options such as capacity building, plant breeding and biotechnology.

Climate Science, Development Practice, and Policy Interactions in Dryland Agroecological Systems

The literature on drought, livelihoods, and poverty suggests that dryland residents are especially vulnerable to climate change. However, assessing this vulnerability and sharing lessons between dryland communities on how to reduce vulnerability has proven difficult because of multiple definitions of vulnerability, complexities in quantification, and the temporal and spatial variability inherent in dryland agroecological systems. In this closing editorial, we review how we have addressed these challenges through a series of structured, multiscale, and interdisciplinary vulnerability assessment case studies from drylands in West Africa, southern Africa, Mediterranean Europe, Asia, and Latin America. These case studies adopt a common vulnerability framework but employ different approaches to measuring and assessing vulnerability. By comparing methods and results across these cases, we draw out the following key lessons: (1) Our studies show the utility of using consistent conceptual frameworks for vulnerability assessments even when quite different methodological approaches are taken; (2) Utilizing narratives and scenarios to capture the dynamics of dryland agroecological systems shows that vulnerability to climate change may depend more on access to financial, political, and institutional assets than to exposure to environmental change; (3) Our analysis shows that although the results of quantitative models seem authoritative, they may be treated too literally as predictions of the future by policy makers looking for evidence to support different strategies. In conclusion, we acknowledge there is a healthy tension between bottom-up/ qualitative/place-based approaches and top-down/quantitative/generalizable approaches, and we encourage researchers from different disciplines with different disciplinary languages, to talk, collaborate, and engage effectively with each other and with stakeholders at all levels.

Is rainfall really changing? Farmers’ perceptions, meteorological data, and policy implications

Understanding farmers’ perceptions of how rainfall fluctuates and changes is crucial in anticipating the impacts of changing climate patterns, as only when a problem is perceived will appropriate steps be taken to adapt to it. This article seeks to: (1) identify southern African farmers’ perceptions of rainfall, rainfall variations, and changes; (2) examine the nature of meteorological evidence for the perceived rainfall variability and change; (3) document farmers’ responses to rainfall variability; and (4) discuss why discrepancies may occur between farmers’ perceptions and meteorological observations of rainfall. Semi-structured interviews were used to identify farmers’ perceptions of rainfall changes in Botswana and Malawi. Resulting perceptions were examined in conjunction with meteorological data to assess perceived and actual rainfall with regards to: what was changing (onset, duration or cessation), and how it was changing (amount, frequency, intensity or inter-annual variability). Most farmers perceived that the rains used to start earlier and end later. Meteorological data provided no evidence to support farmer perceptions of rainfall starting as early as September (south Malawi) or October (Botswana); however, a high inter-annual variability in the timing of the onset was observed alongside an increasing number of dry days and declining amounts of rainfall at the onset and cessation of precipitation. While some rainfall patterns are associated with El Niño-Southern Oscillation (ENSO) fluctuations and larger-scale changes, one explanation for the differences between farmer perceptions and meteorological evidence is that rainfall changes can be easily confused with changes in farming system sensitivity. Our findings suggest that scientists, policymakers, and developers of climate adaptation projects need to be more in tune with farmers and extension workers’ understandings of how weather is changing in order to improve adaptation policy formulation and implementation.

The socioeconomics of food crop production and climate change vulnerability: a global scale quantitative analysis of how grain crops are sensitive to drought

Many studies warn that climate change may undermine global food security. Much work on this topic focuses on modelling crop-weather interactions but these models do not generally account for the ways in which socio-economic factors influence how harvests are affected by weather. To address this gap, this paper uses a quantitative harvest vulnerability index based on annual soil moisture and grain production data as the dependent variable in a Linear Mixed Effects model with national scale socio-economic data as independent variables for the period 1990–2005. Results show that rice, wheat and maize production in middle income countries were especially vulnerable to droughts. By contrast, harvests in countries with higher investments in agriculture (e.g. higher amounts of fertilizer use) were less vulnerable to drought. In terms of differences between the world’s major grain crops, factors that made rice and wheat crops vulnerable to drought were quite consistent, while those of maize crops varied considerably depending on the type of region. This is likely due to the fact that maize is produced under very different conditions worldwide. One recommendation for reducing drought vulnerability risks is coordinated development and adaptation policies, including institutional support that enables farmers to take proactive action.

Landscape diversity and the resilience of agricultural returns: a portfolio analysis of land- use patterns and economic returns from lowland agriculture

BackgroundConventional agriculture is increasingly based on highly specialized, highly productive farms. It has been suggested that 1) this specialization leads to farms that lack resilience to changing market and environmental conditions; and 2) that by decreasing agricultural diversity, the resilience of the farming system also decreases.MethodsWe used agricultural gross margin (GM) forecasts from 1966 to 2010 and remote sensing data from agricultural landscapes in the lowland UK, in conjunction with modern portfolio theory, to test the hypothesis that decreasing land-use diversity results in landscapes that provide higher, but more volatile, economic returns. We considered the role of spatial scale on the expected levels of volatility and resilience of agricultural returns.ResultsWe found that: 1) there was a strong linear trade-off between expected GMs and the expected volatility of those GMs in real lowland agricultural landscapes in the UK; 2) land-use diversification was negatively correlated with expected GMs from agriculture, and positively correlated with decreasing expected volatility in GMs; 3) the resilience of agricultural returns was positively correlated with the diversity of agricultural land use, and the resilience of agricultural returns rose quickly with increased land-holding size at small spatial extents, but this effect diminished after landholdings reached 12,000 hectares.ConclusionsLand-use diversity may have an important role in ensuring resilient agricultural returns in the face of uncertain market and environmental conditions, and land-holding size plays a pivotal role in determining the relationships between resilience and returns at a landscape scale. Creating finer-grained land-use patterns based on pre-existing local land uses may increase the resilience of individual farms, while maintaining aggregate yield across landscapes.

Visitor perceptions of rural landscapes: A case study in the Peak District National Park, England

Maintaining national parks is an integral policy tool to conserve rare habitats. However, because national parks are funded by taxpayers, they must also serve the needs of the general public. Increasingly, and thanks to todays diverse society, there is evidence that this creates challenges for park managers who are pulled in two opposing directions: to conserve nature on the one hand and to meet different visitor expectations on the other. This tension was explored in the Peak District National Park, a rural landscape dominated by heather moorland and sheep farming in Northern England where research was conducted to determine how social class and ethnicity shaped perceptions of the park. Results uncovered that social class played a very strong role in shaping perceptions of this region with middle class respondents reacting far more favourably to the park than people from more working class backgrounds. We observed ethnicity playing a similar role, though our results are less significantly different.

Canadian Biomass Reserves for Biorefining

A lignocellulosic-based biorefining strategy may be supported by biomass reserves, created initially with residues from wood product processing or agriculture. Biomass reserves might be expanded using innovative management techniques that reduce vulnerability of feedstock in the forest products or agricultural supply chain. Forest-harvest residue removal, disturbance isolation, and precommercial thinnings might produce 20-33 x 10(6) mt/yr of feedstock for Canadian biorefineries. Energy plantations on marginal Canadian farmland might produce another 9-20 mt. Biomass reserves should be used to support first-generation biorefining installations for bioethanol production, development of which will lead to the creation of future high-value coproducts. Suggestions for Canadian policy reform to support biomass reserves are provided.