“Preserve and cherish the pale blue dot, the only home we’ve ever known” — Carl Sagan

Changes born of a warming planet are evident to anyone and anyone who takes the time to look. Rising sea levels, retreating glaciers, temperature records that are being broken every year, extreme weather events that were once rare but are now increasingly common.

And then there are the less obvious biotic changes, vast areas of seemingly healthy Joshua trees lacking enough recruitment to sustain their populations. Lizard species exploiting higher elevations and/or abandoning lower elevations. Plants, birds, and pollinator populations in decline. The list goes on.

Documenting these changes is a seemingly Herculean task, yet it is a task that naturalists, including and arguably especially, volunteer community scientists are well positioned to take on. And documenting these changes is critically important. We need to understand the multifaceted impacts of climate change and we need to know how far patterns of biodiversity are departing from baseline levels. That baseline is or could be the target for telling us when or if we have reversed the negative impacts of a warming planet and once again have a healthy world.

While the drivers of modern climate change began with the Industrial Revolution of the 19^th century, the earth’s ability to buffer those effects worked well until the 1970s-1980s. That is when the signal of rising temperatures became evident. So, a true baseline of the species distributions should, ideally, be measured prior to that tipping point. There were a few naturalists who had the presence of mind to understand that change was inevitable and so collected that earlier baseline.

Joseph Grinnell was a leader in that effort, establishing data sets of where mostly birds and mammals, but also reptiles and amphibians, occurred in the early 1900s throughout California. Groups from UC Berkeley and the San Diego Museum of Natural History have resurveyed those same sites Grinnell visited and have documented changes. Not surprisingly, species have not all responded in the same way. Some appear resilient to the levels of climate change so far, while others are more sensitive to those changes. I was able to take advantage of a data set for 1960s era reptile occurrences in what is now Joshua Tree National Park, collected by students and professors from California State University Long Beach, and was able to show that nearly all the lizard species have now shifted their centers of abundance to higher elevations.

Another way to identify departures from a pre 1970s baseline is to use repeat photography. Landscape photographers, collecting images of nature, have created a qualitative catalogue of a world prior to its current warming trajectory. Replicating those images, matching ridgelines, and other stable features (rocks and boulders) can allow modern photographers a means of finding the exact spot where the original photo was taken. From those images we can visually show what change has occurred.

As valuable as those comparisons are, they are limited to the few naturalists and photographers created the early baselines from which to replicate. We need more. Even though some change has already occurred, there are almost certainly greater levels of change on the horizon. Even if data collected today is not a pre-climate change baseline, it is nevertheless a point in time before what are anticipated to be more dramatic shifts in the decades to come. We need to know species occurrences from those points and time for the next generation of naturalists to understand where species once were and what we have lost and to identify targets for restoring healthy ecosystems.

Modern databases such as those being populated through iNaturalist or eBird will provide the foundation for those future comparisons. They provide point data verifying that a species was there and when. However, ideally these data need to be supplemented with total counts on permanent plots or sections of trails. The difference between these types of data is that the former (iNaturalist) data are individual points, whereas the area-constrained counts provide density values. Point data from iNaturalist records do an amazing job of defining species’ ranges and identifying changes at those range boundaries. Over time, and as the climate warms, with area-constrained counts, we can measure decreases or increases in density as habitats become less or more suitable for different species. Both approaches can and should work together to help identify the impacts of climate change on biodiversity.

Human-caused, anthropogenic, climate change is one of the greatest challenges our species of nearly hairless apes has faced since emerging from the African savannas. Greater than wars, famine, or pandemics. The challenge is great because of the potential impact to every living thing on earth, and because our social, political, and economic systems are so resistant to making the necessary changes to reverse the spiral, the falling dominos we have created. The cause of course is our rampant emissions of greenhouse gasses. Reducing those emissions and reversing the climatic changes will require changes in what we eat, what we use to build our homes and cities, and how and how frequently we need to move from point A to point B. So just about everything, and there is the rub. Humans resist change, which is ironic since we have proven ourselves to be the most adaptable species on this blue planet, occupying every biome, every vegetation zone on earth. No other single species can claim that achievement, and no other species has the capacity to reverse what we have wrought. We need to harness our adaptability to restore a healthy planet.

Nullius in verba

Go outside, tip your hat to a chuckwalla (and a cactus), think like a mountain, and be safe.