Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

Menu
  • Home
  • Zoom Interactive Programme
Cliquer pour fermer

Wednesday 8 July - 11:30-13:00 UNESCO Fontenoy - ROOM II

L2.5 - Food and water security under climate change

Large Parallel Session

Chair(s): C. Rosenzweig (NASA Goddard Institute for Space Studies, New York, United States of America)

Lead Convener(s): J.F. Soussana (INRA, Paris, France), T. Oki (University of Tokyo, Tokyo, Japan)

11:30

Future landscapes of food supply and demand and implications for emissions

J.F. Soussana (INRA, Paris, France)

Abstract details
Future landscapes of food supply and demand and implications for emissions

JF. Soussana (1)
(1) Inra, Paris, France

Abstract content

Climate change and the rise in atmospheric CO2 will reorganize food systems and alter agricultural productivity, with impacts on food security, land use and greenhouse gas emissions. Food security is still an issue for about 795 million undernourished people, mostly located in the least developed countries of the planet. The agriculture sector is already affected by climate change, with significant global negative impacts on wheat and maize yields being observed over the last decades. The global food systems would be severely threatened under high end global warming scenarios. The agriculture, forestry and land use sector contributes to 24% of global anthropogenic greenhouse gas (GHG) emissions, with livestock alone estimated to contribute about 14.5% of total human induced emissions when a supply chain approach is considered. Globally, GHG emissions from agriculture could be reduced by 20-30% if less efficient producers would adopt the best practices of their peers, in the same production system and region. Technologies and practices that help reduce emissions exist but are not yet widely used. Those that improve efficiency and plant and animal health also have productivity co-benefits. In addition, the agriculture sector could benefit from carbon offset programs that represent potential additional income. Climate change matters to the agriculture sector. Direct impacts on production range from extreme climatic events, droughts and floods, to thermal stress and reduced yields. A large proportion of low income farmers are highly exposed to climate change. Forward-looking scenarios of plausible agricultural sector developments were developed based on the new IPCC scenario framework. The results in terms of agricultural market developments, land and water use, and GHG emissions going until 2050 highlight the role that demand driven and supply driven changes in the sector could play both for greenhouse gas mitigation and for adaptation to climate change.

11:45

Past and future weather-induced risk in crop production

J. Elliott (University of Chicago, Chicago, United States of America)

Abstract details
Past and future weather-induced risk in crop production

J. Elliott (1)
(1) University of Chicago, Chicago, United States of America

Abstract content
The global food system has seen increased volatility in recent years, with spiking food prices blamed for civil unrest on several continents. Rising prices for global commodity products like soy, meat and palm are increasingly driving deforestation around the globe, and with agriculture increasingly interconnected to global food and energy markets, weather-related risk and supply-side shocks have become a key issue or concern for governments and businesses alike.

Using archives from the Agricultural Model Intercomparison and Improvement Project (AgMIP) and the Intersectoral Impact Model Intercomparison (ISI-MIP), we look first at the impacts of 65 years of continental and global extreme events using observation-driven models and data. We identify the most severe historical events in caloric terms at national to global scales and evaluate the ability of models and model ensembles to identify weather-induced extreme years, correctly assess the magnitude of large-scale extreme events, reproduce historical country-level variability, and reproduce spatial patterns of losses under extreme drought.

We next consider global crop models driven with large ensembles of climate model output (both under historical forcing and with future scenarios) to characterize present day risk and the extent of non-stationary risk in global crop production. We find increasing, and in many cases accelerating risk, of extreme global loss events even in scenarios with little to no climate-induced long-term mean changes. In some cases, one-year global-scale production loss events that would have recently been called 1-in-100 year events are estimated to occur every 30 years by mid-century, and every 10-20 years by end-of-century. We discuss some regional and global protective measures that might be introduced, including increased trade, stock-hoarding, crop breeding, and improved forecasts, monitoring, and modeling. 

11:55

Future landscapes of crop water supply and demand

T. Oki (University of Tokyo, Tokyo, Japan)

Abstract details
Future landscapes of crop water supply and demand

T. Oki (1)
(1) University of Tokyo, Tokyo, Japan

Abstract content

The real hydrological cycles on the Earth are not natural anymore. Humans are now driving changes in atmospheric processes through emission of green-house gases and land cover changes directly and indirectly. Global mean temperature is projected to rise approximately proportional to the cumulative total anthropogenic CO2 emissions from 1870 (AR5, IPCC WGI). Temperature rise itself will have direct impacts on the availability of water resources through changing flow regimes in snow-dominant or glacier-effluent river basins, and it will also be associated with sea level rise because thermal expansion is one of the major causes of observed and projected sea level rises. Further, climate change is projected to alter hydrological cycles: changing temporal and geographical patterns of hydrological components, such as precipitation, evapotranspiration, runoff, and ground water recharge, and particularly in their extremes. Consequently, the frequency of floods and/or droughts is projected to increase some parts of the world.

However, as articulated in the AR5 of IPCC WGII, “Risk of climate-related impacts results from the interaction of climate-related hazards (including hazardous events and trends) with the vulnerability and exposure of human and natural systems”, increasing frequency of natural hazards, such as torrential rainfall or long-lasting heat wave, alone will not cause damages on human and natural systems, and both climate and social changes are relevant for planning sustainable development in the future.

AR5 (WGII) also says “Significant co-benefits, synergies, and tradeoffs exist between mitigation and adaptation and among different adaptation responses; interactions occur both within and across regions”. Mitigation and/or adaptation actions should not be planned in an isolated manner, but should be integrated into wider frameworks, such as integrated water resources management and sustainable development. It would preferably be integrated into a risk management framework assessing and managing possible global risks, and ultimately pursue increasing human well-beings.

These issues will be discussed with reviews of the latest estimates of water demand and supply in the future.

12:10

Planetary opportunities in crop water management: Potential to outweigh cropland expansion

J. Jägermeyr (Potsdam Institute for Climate Impact Research, Potsdam, Germany), J. Jägermeyr (Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany)

Abstract details
Planetary opportunities in crop water management: Potential to outweigh cropland expansion

J. Jägermeyr (1)
(1) Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany

Abstract content

(Authors: Jonas Jägermeyr, â€‹Dieter Gerten, Wolfgang Lucht, Jens Heinke)

 

A major humanitarian challenge for the 21st century is to feed the growing world population in face of climate change and sustainability boundaries. However, as the planetary boundaries for freshwater and land use are being approached rapidly, there is little potential for additional cropland     appropriation or irrigation water diversion. In addition, competition between food production, bioenergy plantations and biodiversity conservation increases pressure, while considerable yield gaps remain in many world regions and various water conservancy methods proved instrumental to boost yields in a sustainable way.In the here presented modeling study we investigate, at global scale, to what degree smart on-farm crop water management might contribute to a sustainable global yield increase. We do this under current and projected future climate conditions and under the constraint of environmental flow requirements to represent the planetary boundary for human freshwater use and its regional pattern. We recalculate from this potential how much cropland expansion could be avoided and also quantify associated financial investment needs. The portfolio of management options studied here consists of methods aiming for elevated crop water productivity (irrigation improvements and expansion with thus saved water) and an optimal use of on-field precipitation water (reducing soil evaporation and collecting surface runoff for supplemental irrigation).Global yield simulations based on hypothetical scenarios of these management opportunities are performed with the process-based agro-biosphere model LPJmL, driven by reanalysis data and GCM ensemble simulations. We consider a range of 20 climate change projections to cover respective uncertainties, and we analyze the effects of increasing CO2 concentration on the crops and their water demand. Crops are represented in a process-based and dynamic way by 12 crop functional types, each for rainfed and irrigated areas, per 0.5° x 0.5° grid cell. Irrigation is represented through a newly implemented dynamic irrigation module that accounts for beneficial and non-beneficial irrigation water consumption.Our results show that irrigation shifts to more efficient systems can save substantial amounts of water (54-76% of non-beneficial water consumption) at the basin level, and if used to transform rainfed into irrigated systems, can increase crop yields significantly in many major river basins (14-18% global production increase). Large-scale irrigation transitions are however very expensive. Moreover, affordable low-tech solutions for small-scale farmers on water-limited croplands can increase yields to a similar extent. A simulated global ~15% yield increase from a low-intensity water management scenario could outweigh, i.e. possibly avoid, an estimated 120 Mha of cropland expansion under current climatic conditions. A maximum-intensity water management scenario shows the potential to increase global yields by more than 35% without expansion or withdrawing additional irrigation water. Climate change will have adverse effects on crop yields in many regions, but as we show such adaptation opportunities have the potential to mitigate or compensate these impacts in many countries. Overall, proper water management (sustainably maximizing on-farm water use efficiency) can substantially increase global crop yields and at the same time relax rates of land cover conversion.

12:20

Agricultural Adaptation to Climate Change in Rich and Poor Countries

D. Lobell (Stanford University, Stanford, CA, United States of America)

Abstract details
Agricultural Adaptation to Climate Change in Rich and Poor Countries

D. Lobell (1)
(1) Stanford University, Department of environmental earth system science, Stanford, United States of America

Abstract content

This talk will review the evidence on the effectiveness of adaptation in reducing climate change impacts in different countries. Much of the model-based evidence is relatively weak, not only in that it relies on models, but that it depends on strong assumptions about what farmers would do in the absence of climate change. A few observational studies have been published in recent years, which will also be reviewed. Overall, the challenge of adapting to climate change is formidable, and rapid learning will be essential for achieving as much reduction in impacts as possible.

12:30

Adaptation to Extreme Weather Events by Farmers in China

J. Huang (Chinese academy of sciences , Beijing, China)

Abstract details
Adaptation to Extreme Weather Events by Farmers in China

J. Huang (1)
(1) Chinese academy of sciences , Center for chinese agricultural policy, Beijing, China

Abstract content

Growing evidence indicates that climate change has aggravated the intensity and frequency of extreme weather events in the past and will future aggravated in the future. Overcoming the challenge of increasing extreme weather events, particularly drought and flood, has captured much attention in many developing countries. In China, the annual average crop area suffering from serious drought and flood has also increased in recent decades. Key issues to be discussed in this presentation include: how farmers have responded or adapted to the extreme weather events? What are major measures that have been taken by farmers when they face serious drought and flood? How effectiveness of these measures in mitigating the risk resulted from the extreme weather events? How policy can facilitate farmers to better adapt to the rising intensity and frequency of extreme weather events in the future? Based on primary data from a large-scale field survey in China, the results show that when faced with severe drought or flood, farmers do take various measures to mitigate the climate risk. Most measures taken by farmers are related to investment in and management of water used in agricultural production. The local irrigation infrastructure, policy supports and early warning information services as well as farmers’ social capita have facilitated farmers to take the adaptive responses. In addition, existing village, household and plot characteristics also significantly Further analysis shows that the adaptation through farmers’ responses significantly reduce crop yield loss and risk of crop yield. The presentation concludes with several policy implications.

12:40

Q&A session

C. Rosenzweig (NASA Goddard Institute for Space Studies, New York, United States of America)

Abstract details
Q&A session
Abstract content