Capturing Change: The Power of Repeat Photography in Unraveling Climate Impact

 By Jim Cornett

A great deal has been discussed regarding how our evolving climate affects natural environments. However, tangible evidence has been difficult to find. There is minimal concrete data about the variety and abundance of plant species from the recent past. How can we ascertain if plant communities have altered since the 1980s, when researchers initially noted that temperatures were rising and droughts were intensifying, especially in California’s deserts?

Some advocates have claimed that desert areas, like Anza-Borrego Desert State Park, will exhibit resilience amidst climatic shifts. As one camper remarked to me, “Desert flora and fauna are well-suited to their environment. A slight increase in heat, a bit more aridity, won’t affect them significantly.”

Is the camper correct? Will desert flora manage to adapt to climate change? To uncover this, I utilized a previously untapped resource of information regarding desert plant life in California: historic landscape photographs. I scoured library archives and museum collections for as many historical landscape images as I could find. All in all, I located nearly one hundred historical photos showcasing plants and vegetation from years gone by in sites we could accurately revisit. Subsequently, I returned to those sites to take contemporary photographs. The old and new photos were contrasted to identify any potential differences. This method is referred to as repeat photography and has been used previously to evaluate landscape transformations, though not specifically in California’s desert areas.

What I uncovered was unexpected, and at times, alarming. Despite the resilience of desert flora, certain species were struggling. Notably concerning was the decline of our most emblematic plants, including ocotillo, teddy bear cholla, and desert fan palm. For instance, within Anza-Borrego Desert State Park, nearly all the historical images revealed a significant reduction in ocotillos today. In one specific instance, all ocotillos had vanished from the location. A similar trend was observed with the teddy-bear cholla, with severe declines noted in each image. In three photographs, the cactus had disappeared entirely. Though desert fan palms depend on upwelling fossil water along faults, persistent drought seems to have adversely affected some palm oases. Particularly alarming was the complete halt in palm reproduction at Seventeen Palms. There were no young palms to replace the aging trees that would eventually perish, nor have the adult palms produced seeds for three consecutive years. Only the palm oasis located in Borrego Palm Canyon appears to be thriving based on repeat photographs, likely due to the Park’s decision to redirect hikers away from the stream corridor towards the canyon’s edges. As a result, palm seedlings are now protected from being trampled by the crowds of visitors who regularly hike up the canyon.

In addition to the effects on individual plant species, regional patterns were observed. Climate change seems to have inflicted the most severe effects on the Colorado Desert. The higher, more northerly Mojave Desert exhibited negative consequences, but these were less pronounced. There was little to no change in plant coverage or composition in the even higher Great Basin Desert to the north. It appears that flora in the hottest and driest regions, the Colorado Desert, is nearing a critical threshold for survival under the new climatic conditions.

I consider these findings to be significant, albeit preliminary. The number of repeat photography sites was less than one hundred, which is inadequate for thorough statistical evaluation. It is hoped that we can enhance these findings with more researchers employing this technique to assess changes. Equally crucial, desert enthusiasts can aid by examining their photographic collections and rephotographing locations they have visited previously. Such old and new photographs would provide a valuable contribution and would be of great interest to scientists.