Human civilization has grown and prospered during a 10,000 yr period of remarkably stable climatic patterns. Different cultures have adapted to specialize in certain foods largely because different places have had conditions that favor one crop or another.
Small Shifts Have Consequences
In our modern society people may only be conscious of weather impacts after prices increase from a smaller harvest. Those living in cities don’t see the everyday effects of heat or rainfall on plants. Yet weather extremes are already affecting the reliability of farm yields. 2019 has provided textbook examples of what weather extremes can do. Do a search for terms like “2019 weather midwest corn” or swap corn for soybeans, or try “2019 weather Australia flood” to be reminded of some of the events. Yet droughts, floods and fires are the extreme events hitting more places each year. Beneath those extreme events is a constant and more insidious shift. The growing season is getting warmer decade by decade, and crops are at their limits of being able to adapt.
While people deal with wide daily and seasonal variations in temperature, plants are less adaptable. Plants need consistency in their seasonal or annual patterns.
The normal bell curve of “normal” rainfall and temperature patterns is different for various regions. Regional difference are why some regions are good for corn, and other regions are better for either rice or wheat. Some places are great for grapes (and wines) while other
places are better for oranges, or coffee. For any particular crop, it is not only the range of temperatures and timing of precipitation, but also the number of days of the growing season for having a seasonal crop reach maturity to be harvested.
Climate Shifts Will be Disastrous for Many Crops
Into this need for plants, let’s look at what we have already seen happen to the “Normal” bell curve for temperature. Below are a series of images taken from the last half hour of a video lecture by Prof David Battisti. I’d encourage everyone to watch the video – to understand well the situation ahead as shared in these few images.
The temperature projections for this century vary, but taking the average of expected temperatures for the different CO2 projections still points to nearly everywhere (red) having odds of seasonal temperatures exceeding the hottest growing season ever experienced are nearly 100%.
Geographic Concerns Spread
Trends to Expect from Temperature and Precipitation
As the planet warms the range of temperatures and timing of precipitation will shift away from what had been the optimal growing conditions for current crops. Especially in tropical and sub-tropical regions, the fertility of plants will RAPIDLY fall off, yielding smaller harvests. Regions that are below the optimal temperature conditions now will briefly enjoy the warmer, optimal conditions. The projections remain grim. By the end of the century, even temperate zones will experience declining harvests.
Net Consequences for Farming
Cereal Killer: Climate Change Stunts Growth of Global Crop Yields – “Scientific American”
A crop-yield analysis reveals that warming temperatures have already diminished the rate of production growth for major cereal crop harvests during the past three decades. … burning fossil fuels, however, is now contributing to the slowing of such rising yields, cutting harvests of wheat 5.5 percent and maize 3.8 percent from what they could have been since 1980, according to a new analysis of yields.”
Later in the article an attempt was made to soften the concerns by saying CO2 increases also raised yields – though the warming harm for wheat outpaced the CO2 benefits. Worse than that is the compounded news of what excess CO2 does to nutritional content.
The great nutrient collapse by Helena Bottemiller Evich
The atmosphere is literally changing the food we eat, for the worse. And almost nobody is paying attention.
The data we have, which look at how plants would respond to the kind of CO2 concentrations we may see in our lifetimes, show these important minerals drop by 8 percent, on average. The same conditions have been shown to drive down the protein content of C3 crops, in some cases significantly, with wheat and rice dropping 6 percent and 8 percent, respectively.”
“In 2014, Myers and a team of other scientists published a large, data-rich study in the journal Nature that looked at key crops grown at several sites in Japan, Australia and the United States that also found rising CO2 led to a drop in protein, iron and zinc.”