People continue to debate climate change, including whether it’s actually happening, how much people contribute to it and if we can stop or reverse it. Precipitation and warming trends in the Rio Grande Valley, however, can’t be denied.
A recent update to the U.S. Department of Agriculture’s zones for growing plants reflects those trends, and could portend changes that might occur, or that might be needed, to the agricultural industry that’s such a big part of our economy.
Hot and dry conditions have been growing longer and more severe in southern Texas and northern Mexico, and appear to have worsened our southern neighbor’s already spotty compliance with the water-sharing treaty between our two countries. The treaty defines how much water each country must feed into the Rio Grande, which communities on both sides of the border use to supply their communities, farms and orchards. Mexico frequently falls behind in its release of water from tributary rivers into the Rio Grande, and current is years behind in its compliance.
Droughts have become commonplace in this region, forcing many local communities to declare water emergencies and restrict residents’ use of water for washing cars, watering lawns and other activities.
During the decade-long drought of the 1990s, climate experts already were predicting that the conditions reflected not an extraordinary weather pattern but a permanent climate shift. The years since then have only added more evidence to support that prediction.
That information reflected a large economic blow to many South Texas farmers. Some lost harvests to the hot and dry conditions; others changed crops, and still others felt compelled to switch from flood irrigation methods to dryland farming or invest in less-wasteful irrigation systems.
The USDA’s most recent plant hardiness zone map, which professional growers and backyard gardeners use to decide what crops to grow, an when to plant them, shows similar changes nationwide.
The map takes weather data from recent decades and provides the coldest average temperatures, first frost dates and other information. On average, those coldest new temperatures are more than two degrees Fahrenheit warmer than the previous map that was published in 2012.
It divides the country into agricultural zones to make the information easier to understand.
For example, the previous map had most of the Valley in zone 9, divided into A and B subzones; the new map places the region solidly in zone 10.
In northern regions the change means that many people now can plant vegetables that do not grow well in cold temperatures, and they might be able to plant them, and thus harvest them, sooner.
But in warmer climes such as the Valley it might be harder to grow delicate herbs and plants that bolt, or transfer their energy from producing leaves and fruit to producing seeds, or trees such as peaches that need winter temperatures to drop to a certain level in order to bear fruit.
We can only speculate whether the warming trend will continue and if it eventually will be reversed. For now, however, it’s clear that climate patterns already are causing changes that can affect our behavior, and our economy.