Climate change and global crop yield: impacts, uncertainties and adaptation

As global mean temperature continues to rise steadily, agricultural systems are projected to face unprecedented challenges to cope with climate change. However, understanding of climate change impacts on global crop yield, and of farmers’ adaptive capacity, remains incomplete as previous global assessments: (1) inadequately evaluated the role of extreme weather events; (2) focused on a small subset of the full range of climate change predictions; (3) overlooked uncertainties related to the choice of crop modelling approach and; (4) simplified the representation of farming adaptation strategies. This research aimed to assess climate change impacts on global crop yield that accounts for the knowledge gaps listed above, based on the further development and application of the global crop model PEGASUS. Four main research topics are presented. First, I investigated the roles of extreme heat stress at anthesis on crop yield and uncertainties related to the use of seventy-two climate change scenarios. I showed large disparities in impacts across regions as extreme temperatures adversely affects major areas of crop production and lower income countries, the latter appear likely to face larger reduction in crop yields. Second, I coordinated the first global gridded crop model intercomparison study, comparing simulations of crop yield and water use under climate change. I found modelled global average crop water productivity increases by up to 17±20.3% when including carbon fertilisation effects, but decreases to –28±13.9% when excluding them; and identified fundamental uncertainties and gaps in our understanding of crop response to elevated carbon dioxide. Third, to link climate impacts with adaptation, I introduced the recently developed concept of representative agricultural pathways and examined their potential use in models to explore farming adaptation options within biophysical and socio-economic constraints. Finally, I explored tradeoffs between increasing nitrogen fertiliser use to close the global maize yield gap and the resulting nitrous oxide emissions. I found global maize production increases by 62% based on current harvested area using intensive rates of nitrogen fertiliser. This raises the share of nitrous oxide emissions associated with maize production from 20 to 32% of global cereal related emissions. Finally, these results demonstrated that in some regions increasing nitrogen fertiliser application, without addressing other limiting factors such as soil nutrient imbalance and water scarcity, could raise nitrous oxide emissions without enhancing crop yield

Global crop yield response to extreme heat stress under multiple climate change futures

Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (ΔY = −12.8 ± 6.7% versus − 7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (ΔY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (ΔY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries

Guillaume Apollinaire

Since 1991, there exists a necessary reference concerning Guillaume Apollinaire as an art critique : Tome II of Oeuvres en prose complètes published by the “Bibliothèque de la Pléiade”. In contrast with the edition of Chroniques d’art by L.-C. Breunig which has just been re-issued in the Folio collection, this volume presents all the texts Apollinaire devoted to art criticism, without cutting sections and, we would even be tempted to say, “without censoring”. Indeed, it must be recognized tha..

Brush and Pen

The publication of Magritte’s complete writings in a volume edited by André Blavier means that the Belgian painter will be joining fellow artists Malevich and Matisse on the M-shelves of French booksellers. According to Schwitters, this is very much the elite bookshelf for 20th-century art, containing as it does the Monstructivists Malevich, Moholy-Nagy, Mondrian and, of course, the German artist’s Merz. This alphabetical cohabitation occasioned by publishing events, is alogical, a piece of z..

Zasady nowej ordynacji wyborczej do Sejmu i Senatu

Digitalizacja i deponowanie archiwalnych zeszytów RPEiS sfinansowane przez MNiSW w ramach realizacji umowy nr 541/P-DUN/201

Le Pinceau et la plume

La publication des Ecrits complets de Magritte, édités par André Blavier, permet au peintre belge d’accéder, chez les libraires à la lettre “M”, aux côtés de Malévitch et de Matisse. Selon Schwitters, c’est l’étagère élue pour l’art du XXe siècle, dominé par la lettre M qui regroupait au sein du Monstructivism, Malévitch, Moholy-Nagy, Mondrian et naturellement Merz. Cette cohabitation alphabétique inattendue, provoquée par l’actualité éditoriale, relève de l’alogisme, du zaoum mais Magritte p..

Implications of climate mitigation for future agricultural production

Climate change is projected to negatively impact biophysical agricultural productivity in much of the world. Actions taken to reduce greenhouse gas emissions and mitigate future climate changes, are thus of central importance for agricultural production. Climate impacts are, however, not unidirectional; some crops in some regions (primarily higher latitudes) are projected to benefit, particularly if increased atmospheric carbon dioxide is assumed to strongly increase crop productivity at large spatial and temporal scales. Climate mitigation measures that are implemented by reducing atmospheric carbon dioxide concentrations lead to reductions both in the strength of climate change and in the benefits of carbon dioxide fertilization. Consequently, analysis of the effects of climate mitigation on agricultural productivity must address not only regions for which mitigation is likely to reduce or even reverse climate damages. There are also regions that are likely to see increased crop yields due to climate change, which may lose these added potentials under mitigation action. Comparing data from the most comprehensive archive of crop yield projections publicly available, we find that climate mitigation leads to overall benefits from avoided damages at the global scale and especially in many regions that are already at risk of food insecurity today. Ignoring controversial carbon dioxide fertilization effects on crop productivity, we find that for the median projection aggressive mitigation could eliminate ~81% of the negative impacts of climate change on biophysical agricultural productivity globally by the end of the century. In this case, the benefits of mitigation typically extend well into temperate regions, but vary by crop and underlying climate model projections. Should large benefits to crop yields from carbon dioxide fertilization be realized, the effects of mitigation become much more mixed, though still positive globally and beneficial in many food insecure countries

Climate analogues suggest limited potential for intensification of production on current croplands under climate change

Climate change could pose a major challenge to efforts towards strongly increase food production over the coming decades. However, model simulations of future climate-impacts on crop yields differ substantially in the magnitude and even direction of the projected change. Combining observations of current maximum-attainable yield with climate analogues, we provide a complementary method of assessing the effect of climate change on crop yields. Strong reductions in attainable yields of major cereal crops are found across a large fraction of current cropland by 2050. These areas are vulnerable to climate change and have greatly reduced opportunity for agricultural intensification. However, the total land area, including regions not currently used for crops, climatically suitable for high attainable yields of maize, wheat and rice is similar by 2050 to the present-day. Large shifts in land-use patterns and crop choice will likely be necessary to sustain production growth rates and keep pace with demand

Climate Change Effects on Agriculture: Economic Responses to Biophysical Shocks

Agricultural production is sensitive to weather and thus directly affected by climate change. Plausible estimates of these climate change impacts require combined use of climate, crop, and economic models. Results from previous studies vary substantially due to differences in models, scenarios, and data. This paper is part of a collective effort to systematically integrate these three types of models. We focus on the economic component of the assessment, investigating how nine global economic models of agriculture represent endogenous responses to seven standardized climate change scenarios produced by two climate and five crop models. These responses include adjustments in yields, area, consumption, and international trade. We apply biophysical shocks derived from the Intergovernmental Panel on Climate Change's representative concentration pathway with end-of-century radiative forcing of 8.5 W/m(sup 2). The mean biophysical yield effect with no incremental CO2 fertilization is a 17% reduction globally by 2050 relative to a scenario with unchanging climate. Endogenous economic responses reduce yield loss to 11%, increase area of major crops by 11%, and reduce consumption by 3%. Agricultural production, cropland area, trade, and prices show the greatest degree of variability in response to climate change, and consumption the lowest. The sources of these differences include model structure and specification; in particular, model assumptions about ease of land use conversion, intensification, and trade. This study identifies where models disagree on the relative responses to climate shocks and highlights research activities needed to improve the representation of agricultural adaptation responses to climate change