In a semi-arid region like the southwestern Mojave, the presence of water and climate variations influence where biotic communities flourish. Human impact on plant communities may create barriers to natural plant community development and migration. Related plant and animal extinctions may then occur, creating a loss in all-around biodiversity, as formerly established species are eliminated and new species coming into a region simply don’t provide habitat for keystone species. As long-term plant communities are exterminated, invasive species tend to establish themselves. In the southern Mojave Desert this has led to increase in wildfires and loss of habitat for many native animal species. We’ve watched parts of the Mojave burn over the last ten years that will take a hundred years to recover.
Cycles of wildfires encouraging the growth of nonnative invasive plants has been shown to be related to establishment of nonnative invasive species which then provide more biomass for future fires and even fewer amenable habitats for established Mojave Desert animal communities.
There were USGS studies a decade ago indicating slight overall increase in precipitation in the desert between 1892 and 1996. Now, in 2012, these numbers are less promising than they sounded back then. We’ve had a monumental increase in human population over the last twenty years particularly along the highly populated Interstate 15 corridor which bisects the southern Mojave Desert and the Highway 14 corridor, at the northern edge of our region, thus draining any excess precipitation that occurs due to human need for water.
I don’t know anyone living here, who has been here a while (I’ve been here since 1981), who hasn’t been talking about regional climate change over the last five to ten years. The talk is increasing. I don’t think this is some kind of Millennium Fever (or maybe I should say 2012 Fever). It is talk based on long-time residents noticing changes in climate that may be more extreme than subtle year to year variations. Here at Rainshadow Farm the rainfall patterns are changing. And the winds are not only intensifying but they are becoming more frequent. Yes, the high desert is windy. However, even five years ago, the winds at Rainshadow Farm had a different ebb and flow to them, seasonally.
The United Nations International Panel on Climate Change predicted in 2007 that in the Western portion of the United States there would likely be increased drying with a likelihood of longer wildfire seasons and more intense fires. In California we have observed over the last decade that this already seems to be occurring.
Changes in wind patterns and decreased snowpack and snow cover in mountainous regions in the western United States have also been predicted. Annual-mean precipitation is been projected to decrease in the Southwest of the United States, with increase over the rest of the continent. No models have been done specifically for the Mojave Desert and, while it is good to bear in mind that weather patterns are among the most complex of earth systems, those of us who want to raise small amounts of food here may be wise to also bear in mind that we’ve begun in semi-arid conditions. Food producers in the southern Mojave Desert, particularly those of us close to the mountain ranges, on the piedmont, like Rainshadow Farm, would be wise to plan for growing with no more than 6-9 inches of rain annually in such unpredictable times. This is especially a consideration given the currently lack of coherent water planning along with few constraints on development in the region.