Debbie Hemming

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.

Increase in water-use efficiency and underlying processes in pine forests across a precipitation gradient in the dry Mediterranean region over the past 30 years.

Motivated by persistent predictions of warming and drying in the entire Mediterranean and other regions, we have examined the interactions of intrinsic water-use efficiency (Wi) with environmental conditions in Pinus halepensis. We used 30-year (1974–2003) tree-ring records of basal area increment (BAI) and cellulose 13C and 18O composition, complemented by short-term physiological measurements, from three sites across a precipitation (P) gradient (280–700xa0mm) in Israel. The results show a clear trend of increasing Wi in both the earlywood (EW) and latewood (LW) that varied in magnitude depending on site and season, with the increase ranging from ca. 5 to 20% over the study period. These Wi trends were better correlated with the increase in atmospheric CO2 concentration, Ca, than with the local increase in temperature (~0.04°C year−1), whereas age, height and density variations had minor effects on the long-term isotope record. There were no trends in P over time, but Wi from EW and BAI were dependent on the interannual variations in P. From reconstructed Ci values, we demonstrate that contrasting gas-exchange responses at opposing ends of the hydrologic gradient underlie the variation in Wi sensitivity to Ca between sites and seasons. Under the mild water limitations typical of the main seasonal growth period, regulation was directed at increasing Ci/Ca towards a homeostatic set-point observed at the most mesic site, with a decrease in the Wi response to Ci with increasing aridity. With more extreme drought stress, as seen in the late season at the drier sites, the response was Wi driven, and there was an increase in the Wi sensitivity to Ca with aridity and a decreasing sensitivity of Ci to Ca. The apparent Ca-driven increases in Wi can help to identify the adjustments to drying conditions that forest ecosystems can make in the face of predicted atmospheric change.

On the 13C/12C isotopic signal of day and night respiration at the mesocosm level.

While there is currently intense effort to examine the (13)C signal of CO(2) evolved in the dark, less is known on the isotope composition of day-respired CO(2). This lack of knowledge stems from technical difficulties to measure the pure respiratory isotopic signal: day respiration is mixed up with photorespiration, and there is no obvious way to separate photosynthetic fractionation (pure c(i)/c(a) effect) from respiratory effect (production of CO(2) with a different delta(13)C value from that of net-fixed CO(2)) at the ecosystem level. Here, we took advantage of new simple equations, and applied them to sunflower canopies grown under low and high [CO(2)]. We show that whole mesocosm-respired CO(2) is slightly (13)C depleted in the light at the mesocosm level (by 0.2-0.8 per thousand), while it is slightly (13)C enriched in darkness (by 1.5-3.2 per thousand). The turnover of the respiratory carbon pool after labelling appears similar in the light and in the dark, and accordingly, a hierarchical clustering analysis shows a close correlation between the (13)C abundance in day- and night-evolved CO(2). We conclude that the carbon source for respiration is similar in the dark and in the light, but the metabolic pathways associated with CO(2) production may change, thereby explaining the different (12)C/(13)C respiratory fractionations in the light and in the dark.

How uncertain are climate model projections of water availability indicators across the Middle East

The projection of robust regional climate changes over the next 50 years presents a considerable challenge for the current generation of climate models. Water cycle changes are particularly difficult to model in this area because major uncertainties exist in the representation of processes such as large-scale and convective rainfall and their feedback with surface conditions. We present climate model projections and uncertainties in water availability indicators (precipitation, run-off and drought index) for the 1961–1990 and 2021–2050 periods. Ensembles from two global climate models (GCMs) and one regional climate model (RCM) are used to examine different elements of uncertainty. Although all three ensembles capture the general distribution of observed annual precipitation across the Middle East, the RCM is consistently wetter than observations, especially over the mountainous areas. All future projections show decreasing precipitation (ensemble median between −5 and −25%) in coastal Turkey and parts of Lebanon, Syria and Israel and consistent run-off and drought index changes. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) GCM ensemble exhibits drying across the north of the region, whereas the Met Office Hadley Centre work Quantifying Uncertainties in Model ProjectionsAtmospheric (QUMP-A) GCM and RCM ensembles show slight drying in the north and significant wetting in the south. RCM projections also show greater sensitivity (both wetter and drier) and a wider uncertainty range than QUMP-A. The nature of these uncertainties suggests that both large-scale circulation patterns, which influence region-wide drying/wetting patterns, and regional-scale processes, which affect localized water availability, are important sources of uncertainty in these projections. To reduce large uncertainties in water availability projections, it is suggested that efforts would be well placed to focus on the understanding and modelling of both large-scale processes and their teleconnections with Middle East climate and localized processes involved in orographic precipitation.

The Hydrological Cycle of the Mediterranean

This chapter discusses results of current and future-projected water cycle components over the Mediterranean region. Results are presented from an ensemble of CMIP3 multi-model simulations (here after referred to as Mariotti) and from the Meteorological Research Institute’s (MRI) 20 km grid global climate model. Referred to as CMIP3 results are surprisingly close to MRI. The projected mean annual change in the rate of precipitation (P) across the region (for sea and land), is projected to decrease by the end of the 21st century by −11% and −10%, respectively, for the MRI and Mariotti runs. Projected changes in evaporation (E) are +9.3% (sea) and −3.6% (land) for JMA runs, compared to +7.2% (sea) and −8.1% (land) in Mariotti’s study. However, no significant difference of the projected change in P–E over the sea body is found between these two studies. E over the eastern Mediterranean was projected to be higher than the western Mediterranean, but the P decrease was projected to be lower. The net moisture budget, P–E, shows that the eastern Mediterranean is projected to become even drier than the western Mediterranean. The river model projects significant decreases in water inflow to the Mediterranean of about −36% by the end of the 21st century in the MRI run (excluding the Nile). The Palmer Drought Severity Index (PDSI), which reflects the combined effects of precipitation and surface air temperature (Ts) changes, shows a progressive and substantial drying of Mediterranean land surface over this region since 1900 (−0.2 PDSI units/decade), consistent with a decrease in precipitation and an increase in Ts (not shown). The last section of this chapter reports on components of the hydrological cycle from five climate model projections for the Mediterranean region. Three of these models have an interactive Mediterranean Sea (MPI, ENEA, Meteo-France), and two are versions of the Met Office Hadley Centre regional model (HadRM3-MOSES2, HadRM3-MOSES1) with different land surface schemes. The focus of this section is upon changes in evapotranspiration, and how these changes could be important in controlling available renewable water resources (runoff). These r indicate that rainfall is projected to decline across large areas by over −20% in all of the models, although in the Meteo-France model the central part of the northern Mediterranean domain, ie. southern Italy and Greece, has areas of increase as well as decrease. In pockets of Turkey, the eastern Mediterranean, Italy and Spain, projections from the MPI, HadRM3-MOSES2, HadRM3-MOSES1 and ENEA models are for decreases in summer rainfall of −50% or more. Consistent with the global model projections, each of the five high-resolution models simulate increasing temperatures and decreasing evapotranspiration and precipitation for much of the Mediterranean region by the middle of this century. The strongest and most widespread reductions in precipitation are projected to occur in the spring and summer seasons, while reductions in evapotranspiration are greatest in summer.

Climate Impact Assessments

This chapter highlights key climate impacts, hazards and vulnerabilities and associated indicators that have been used to assess current (recent) climate impacts at each of the case-study sites. The aim is to illustrate some of the wide range of information available from individual case studies and highlight common themes that are evident across multiple case-study locations. This is used to demonstrate linkages and sensitivities between the specific climate impacts of relevance for each case-study type (urban, rural and coastal) and the key climate hazards and biogeophysical and social vulnerabilities representing the underlying drivers and site conditions. For some impacts, there are clear, direct links with climate events, such as heat stress and flooding, while for others, such as energy supply and demand, the causal relationships are more indirect, via a cascade of climate, social and economic influences. Water availability and extreme temperatures are common drivers of current climate impacts across all case studies, including, for example, freshwater supply and heat stress for urban populations; irrigation capacity and growing season length for agricultural regions; and saltwater intrusion of aquifers and tourist visitor numbers at coastal locations. At some individual case-study locations, specific impacts, hazards and/or vulnerabilities are observed, such as peri-urban fires in Greater Athens, infrastructure vulnerability to coastal flooding in Alexandria, groundwater levels in Tel Hadya and vector-borne diseases in the Gulf of Oran. Throughout this chapter, evidence of current climate impacts, hazards and vulnerabilities from each of the case studies is detailed and assessed relative to other case studies. This provides a foundation for considering the wider perspective of the Mediterranean region as a whole, and for providing a context from which to assess consequences of future climate projections and consider suitable adaptation options.

Integration of the Climate Impact Assessments with Future Projections

Climate projections are essential in order to extend the case-study impacts and vulnerability assessments to encompass future climate change. Thus climate-model based indicators for the future (to 2050 and for the A1B emissions scenario) are presented for the climate and atmosphere theme (including indices of temperature and precipitation extreme events), together with biogeophysical and socioeconomic indicators encompassing the other case-study themes. For the latter, the specific examples presented here include peri-urban fires, air pollution, human health risks, energy demand, alien marine species and tourism (attractiveness and socio-economic consequences). The primary source of information about future climate is the set of global and regional model simulations performed as part of CIRCE. These have the main novel characteristic of incorporating a realistic representation of the Mediterranean Sea including coupling between sea and atmosphere. These projections are inevitably subject to uncertainties relating to unpredictability, model structural uncertainty and value uncertainty. These uncertainties are addressed by taking a multi-model approach, but problems remain, for example, due to a systematic cold bias in the CIRCE models. In the context of the case-study integrated assessments, there are also uncertainties ‘downstream’ of climate modeling and the construction of climate change projections – largely relating to the modeling of impacts. In addition, there are uncertainties associated with all socio-economic projections used in the case studies – such as population projections. Thus there are uncertainties inherent to all stages of the integrated assessments and it is important to consider all these aspects in the context of adaptation decision making.

Synthesis and the Assessment of Adaptation Measures

The final stage of the CIRCE case-studies integrated assessment involved identification and evaluation of the effectiveness of local and regional adaptation options in collaboration with stakeholders, and in the context of wider national adaptation policies and strategies. This stage provides a synthesis of both the case-study work and the wider CIRCE project since it draws on the case-study indicators for present and future periods together with wider CIRCE work on adaptation options, particularly in the thematic areas of agriculture, forestry and ecosystems, and Mediterranean communities. This synthesis and evaluation links impacts and vulnerability with adaptation, and also benefits strongly from the local stakeholder workshops held towards the end of the project. Lessons learnt and key messages from the CIRCE case studies are presented. While the objectives of the CIRCE case studies have generally been achieved, a number of research gaps and needs remain.

Physical and Socio-economic Indicators

A set of physical and social indicators relevant to each Mediterranean case study has been developed within the context of the CIRCE case studies integrating framework. This framework approach provides a systematic means of structuring indicator selection and helps to provide a scientific basis for the assessment of climate-related impacts and vulnerability. A detailed set of criteria was developed to select and refine indicators through an iterative process of review and consultation. Indicators represent key issues related to climate variability and change for each of the case-study locations. Seven key indicator themes are identified: climate and atmosphere; marine and coastal systems; terrestrial ecosystems and biodiversity; freshwater systems; agriculture and forestry; human health and well being; and, the economy. A number of core indicators are common to all case studies (for identifying common/disparate trends), others are common across generic case studies (urban, rural, coastal), and some are case-study specific. Data and methodological challenges in the indicator assessment included: data availability and quality limitations; distinguishing impacts from vulnerabilities, and climate from non-climate influences; and, identifying thresholds and coping ranges. Despite these difficulties, the selected set of indicators proved a useful and accessible tool for monitoring trends and portraying key information to regional stakeholders.

Stable isotopes as indicators, tracers and recorders of ecological change : synthesis and outlook

Publisher Summary The chapter presented here explores a diversity of ways in which stable isotopes inform present and future changes in a wide variety of ecological systems. The recent advances in contemporary research are highlighted, focusing on the knowledge and methodologies that have been developed during the past two decades. These approaches cover a wide range of time and space scales and levels of biological organization. As summarized by Ehleringer and Dawson, stable isotopes are powerful tools in ecological studies for tracing, recording, sourcing, and integrating different ecological parameters. Further, as noted by Dawson and Siegwolf, with environmental changes occurring at unprecedented rates in the earths history, stable isotope methods and applications will undoubtedly serve a critical role in documenting the nature and magnitude of change, as well as highlighting solutions for mitigating ecological impacts that threaten the future of all organisms. This chapter provides a synthesis of the major findings, knowledge gaps, and outlooks for future research on the use of stable isotopes as indicators, tracers, and recorders of ecological change.