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.
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.