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. 2018 Sep 15;259:329-344.
doi: 10.1016/j.agrformet.2018.05.013. Epub 2018 Jun 1.

Climate Shifts Within Major Agricultural Seasons for +1.5 and +2.0 °C Worlds: HAPPI Projections and AgMIP Modeling Scenarios

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Climate Shifts Within Major Agricultural Seasons for +1.5 and +2.0 °C Worlds: HAPPI Projections and AgMIP Modeling Scenarios

Alex C Ruane et al. Agric For Meteorol. .
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Abstract

This study compares climate changes in major agricultural regions and current agricultural seasons associated with global warming of +1.5 or +2.0 °C above pre-industrial conditions. It describes the generation of climate scenarios for agricultural modeling applications conducted as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Coordinated Global and Regional Assessments. Climate scenarios from the Half a degree Additional warming, Projections, Prognosis and Impacts project (HAPPI) are largely consistent with transient scenarios extracted from RCP4.5 simulations of the Coupled Model Intercomparison Project phase 5 (CMIP5). Focusing on food and agricultural systems and top-producing breadbaskets in particular, we distinguish maize, rice, wheat, and soy season changes from global annual mean climate changes. Many agricultural regions warm at a rate that is faster than the global mean surface temperature (including oceans) but slower than the mean land surface temperature, leading to regional warming that exceeds 0.5 °C between the +1.5 and +2.0 °C Worlds. Agricultural growing seasons warm at a pace slightly behind the annual temperature trends in most regions, while precipitation increases slightly ahead of the annual rate. Rice cultivation regions show reduced warming as they are concentrated where monsoon rainfall is projected to intensify, although projections are influenced by Asian aerosol loading in climate mitigation scenarios. Compared to CMIP5, HAPPI slightly underestimates the CO2 concentration that corresponds to the +1.5 °C World but overestimates the CO2 concentration for the +2.0 °C World, which means that HAPPI scenarios may also lead to an overestimate in the beneficial effects of CO2 on crops in the +2.0 °C World. HAPPI enables detailed analysis of the shifting distribution of extreme growing season temperatures and precipitation, highlighting widespread increases in extreme heat seasons and heightened skewness toward hot seasons in the tropics. Shifts in the probability of extreme drought seasons generally tracked median precipitation changes; however, some regions skewed toward drought conditions even where median precipitation changes were small. Together, these findings highlight unique seasonal and agricultural region changes in the +1.5°C and +2.0°C worlds for adaptation planning in these climate stabilization targets.

Figures

Figure 1:
Figure 1:
+1.5 °C World (a,c,e,g,i) temperature and (b,d,f,h,j) precipitation changes for (a,b) all land areas and seasons; (c,d) rainfed maize; (e,f) rainfed wheat; (g,h) rainfed rice; (i,j) rainfed soy. These maps are the basis for estimating local climate change patterns between the 1995 Climate used by AgMIP protocols and the 2010 climate used by HAPPI. Hatch marks for temperature indicate that median changes are greater than twice the range among GCMs, and hatch marks for precipitation indicate agreement on the direction of change by 4 of the 5 HAPPI models. Grid cells with <10ha rainfed crop area in the SPAM dataset (You et al., 2014) are omitted to focus on regions with substantial production.
Figure 2:
Figure 2:
+2.0 °C World (a,c,e,g,i) temperature and (b,d,f,h,j) precipitation changes for (a,b) all land areas and seasons; (c,d) rainfed maize; (e,f) rainfed wheat; (g,h) rainfed rice; (i,j) rainfed soy. Hatch marks and area mask as in Figure 1.
Figure 3:
Figure 3:
Classes of +1.5 °C World local (a,c,e,g) temperature and (b,d,f,h) precipitation change deviations for growing seasons compared to annual changes for (a,b) rainfed maize; (c,d) rainfed wheat; (e,f) rainfed rice; (g,h) rainfed soy. ‘Substantially’ different indicates that growing season change differences in at least 3 out of the 5 HAPPI models changed at a pace that was ‘faster’ or ‘slower’ than 0.2 °C for temperatures or 5% for precipitation compared to the annual mean, while ‘Consistently’ different indicates that all 5 HAPPI GCMs agreed on the sign of difference. Areas that meet both the ‘substantially’ and ‘consistently’ criteria are designated as ‘substantially’ different. Area mask as in Figure 1. Note that a Figure S3 presents corresponding results for the +2.0 °C World.
Figure 4:
Figure 4:
Shifts in extreme conditions for rainfed maize season in +1.5 °C World. (a) Change in the frequency of extreme heat years (above 90th percentile in current climate); (b) change in the frequency of extreme drought years (below 10th percentile in current climate); (c) additional extreme heat years in the +2.0 C World compared to the +1.5 C World; (d) additional extreme drought years in the +2.0 C World compared to the 1.5 C World; (e) change in the skewness of seasonal temperature distribution; (f) change in the skewness of seasonal precipitation distribution. Hatch marks in (a) and (b) indicate reduction in frequency of more than ¼ or increases of more than ½ Regions marked as inconsistent in (e,f) unless 2 of the 3 HAPPI daily GCMs demonstrate substantial shifts in skewness (percentile change differences greater than 0.1 °C for temperature and 2% for precipitation). Area mask as in Figure 1c-d.
Figure 5:
Figure 5:
+1.5 °C World HAPPI projected (a,c,e,g) temperature and (b,d,f,h) precipitation changes, weighted by cropped area within the top 10 producing countries (presented in descending order from left to right) for (a,b) maize; (c,d) wheat; (e,f) rice; (g,h) soy.
Figure 6:
Figure 6:
+2.0 °C World HAPPI projected (a,c,e,g) temperature and (b,d,f,h) precipitation changes, weighted by cropped area within the top 10 producing countries (presented in descending order from left to right) for (a,b) maize; (c,d) wheat; (e,f) rice; (g,h) soy.
Figure 7:
Figure 7:
HAPPI and CMIP5 RCP4.5 (a) temperature changes and (b) precipitation changes for annual conditions across all land areas as well as maize, wheat, rice, and soy seasons weighted according to cropped area. Symbols represent HAPPI simulations, while box-and-whisker diagrams indicate CMIP5 median projections and their interquartile range, while whiskers extend to the last point within an additional 1.5 times the interquartile range.

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