If we imagine really bad things, it can affect crop yields. • Watts Up With That?

Gotta love this study:

My emphasis. Oh, and that’s all RCP 8.5 plugged into their imagine engine.

abstract

Previous analyzes of the probability of global bread basket failure have extrapolated risk based on the historical relationship between climate and output. However, climate change is causing unprecedented global eventswhich may exceed the critical thresholdS and reduced output, even without historical precedent. This means that we are likely to underestimate climate risk to our food system. In the case of wheat, some regions of the United States and China show little historical relationship between yield and temperature, but temperature extremes can now exceed physiologically important thresholds in wheat. Unprecedented Extreme Simulation (UNSEEN) Group approaches use large groups to generate unprecedentedly plausible events that could inform our assessment of risk to Crops. We use the UNSEEN method with a large set of stored seasonal forecasts to generate thousands of plausible events over the past 40 years and compare the results with extreme temperatures and precipitation observed over the past 40 years. history. In the midwest US, temperature extremes that could occur about once in 100 years in 1981 now have a repeat cycle of 1 in 6 years, while in China the current return cycle is 1 year -16 years. This means that in the midwestern United States, extreme temperatures that once had a 1% chance of occurring in 1981 now have a 17% chance of occurring in any given year, while in China, chance increased from 1% to 6%. Record years exceeding the critical threshold for enzymes in wheat are now more likely than in the past, and these record hot years are linked to extremely dry conditions in both locations. . Using topographic elevation and wind anomalies from the UNSEEN population, we demonstrate that strong inland winds pull dry air towards these regions during extremely hot and dry invisible events. We describe plausible extremes from the UNSEEN set that can be used to help visualize unforeseen events, including a composite event in which large impacts occur simultaneously in both regions. two regions, providing information for adaptation planning in these areas. Recent temperature extremes, especially in the midwestern United States, are unlikely to be a good representation of what might happen over the next few years given today’s climate and local stakeholders. may perceive their risk to be lower than it actually is. We found that there was a greater chance of surprises in these regions if people were only analyzing risk based on historical data sets.

Introduce

Due to the global interconnectedness of the world food system, simultaneous shocks to major food grain producing areas (wheat bowls) can significantly affect the price and availability of food. essential foods. Several studies have attempted to quantify the risk of multiple breadbasket failures due to climate shocks alone^first,2,3. These studies mainly extrapolate from historical models, quantifying the risk that past climate shocks may co-occur in the future. However, climate change brings new and unprecedented events, which may have different consequences than those experienced in the past, and thus historical analyzes can our current risk low price. In this study, we focus on historical events, instead presenting how the risk visualization of historically unprecedented events could cross important thresholds in rice-producing regions. Great noodles of the United States and China.

Most studies that quantify crop failure risk use historical relationships between climate and crop yields as the basis for assessing how future or unprecedented climate states may affect to productivity. For example² used historical yields to determine critical water pressure thresholds in the corn-growing regions of the United States and China, then they examined variation in the risk of this threshold using large populations to simulate unprecedented extreme conditions. Estimates of the failure risk of multiple bread baskets for different crops also apply this method, first estimating the relationship between climate and yield from historical data, then which extrapolates yield results based on changes to yield-related temperature and precipitation variables historically.⁴ In some regions, more than 50% of historical yield variations can be attributed to weather⁵.

However, under changing climate conditions, the climate yield relationship will change. Never-before-seen climates and unprecedented events may have a larger impact on crops than would be expected from a simple extrapolation of historical association. With regard to temperature in particular, we can assume that unprecedented high temperatures can cause crop failure, even if there is no historical relationship between yield and temperature. The non-linearity in plant responses to heat stress could mean that the future looks markedly different from the past. In addition, climate stressors can combine with other pressures to threaten agricultural productivity; these include conflicts, pests, diseases, soil quality, seed quality and irrigation for example.

Wheat (Triticum aestivum L.) yield in parts of the US and China did not show a strong relationship with temperature in past observed or simulated datasets⁶and so the extreme temperatures in these areas are often not included in models of bread basket failure.⁴. However, physiological models demonstrate that wheat plants are sensitive to temperature during several key growth stages.⁷. In general, prolonged periods of extreme heat lead to faster leaf aging and reduced leaf expansion and radiation efficiency. Short-lived heat events are especially harmful during sensitive stages of growth such as stem elongation. Excessive temperature during nut filling can reduce the growth rate and number of seeds^8,9while heat stress during bloom and can lead to partial or complete infertility of flower buds^ten,11.

Simulations later in the century show that unprecedented temperatures are likely to affect yields when higher thresholds are crossed.^twelfth In fact, statistical and process-based models tend to agree that warming will negatively impact wheat yields.^13,8and reviews of different types of models have found consensus that global wheat yields may be negatively affected by rising temperatures with climate change.^14,15. One solution to assess the impact of this nonlinearity is to use crop model simulations that can incorporate critical thresholds.^16,17 However, many of these crop models are developed based on historical yields, and many of them focus on annual extremes and “probable” ranges, rather than on high-impact event.

New methods for simulating unprecedented extremes could broaden our understanding of what could happen beyond historical events. Large sets of physically-based climate models can provide a larger sample of “alternative reality” for computing extreme value statistics.^18,19,20 One example is the unprecedented Simulated Extremes approach using ENsembles (UNSEEN), which uses a large set of stored forecasts to better understand extremes.²¹.

To date, most studies of UNSEEN events or climate plots have departed from a historical extreme event that has already occurred, assessing reasonable changes in frequency and magnitude. (e.g. Hurricane Desmond²²). This approach has also been used to derive similar future effects of historical events, such as soybeans (Glycine max (L.) Merr.) future drought¹⁷.

The UNSEEN method can also be used to discover synthetic events—events with no historical similarity—if the models have been properly evaluated for their ability to produce actual events.²³. Climate storylines that illustrate how record-breaking extreme events can happen can expand our imaginations to capture events that are plausible but have never been experienced before. Given that adaptation to climate change tends to be driven by people’s lived experience of extreme events^24,25,26,27 Visualizing such events before they occur can aid in preparedness and adaptation to climate change.

In this study, we use the UNSEEN method to look at unprecedented heat events in two wheat-producing regions of the world’s breadbasket, the United States and China. First, we assembled a large set of stored region-by-region forecasts for temperature and precipitation, estimating how often temperatures exceeded the critical rise threshold. We estimate changes to the return cycle of temperature extremes with climate change and consider the possibility of dual extremes of high temperature and low precipitation in each region. While many other studies focus on climate change in the distant future, we explore how today’s climate and risks have changed compared to the recent past, complementing our work.^first.

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