Rapacciuolo G, Maher SP, Schneider AC, Hammond TT, Jabis MD, Walsh RE, Iknayan KJ, Walden GK, Oldfather MF, Ackerly DD, Beissinger SR

Understanding recent biogeographic responses to climate change is fundamental for improving our predictions of likely future responses and guiding conservation planning at both local and global scales. Commonly, studies conclude that climate change underlies observed responses if those responses are akin to those expected given ubiquitous increases in temperature – collectively termed a warming fingerprint. However, the influence of climate change on species and communities is likely to be much more complex than the simple influence of temperature increases. We show that many of the responses of plants, birds, mammals and butterflies to 20th century climate change across California do not appear to be consistent with a warming fingerprint, with downslope shifts in elevation being as common as upslope shifts across a number of taxa and many demographic and community responses being inconsistent with upslope shifts. We identify a number of potential direct and indirect mechanisms for these responses, including the influence of aspects of climate change other than temperature (e.g., the shifting seasonal balance of energy and water availability), differences in each taxon’s sensitivity to climate change, trophic interactions, as well as land‐use change. Finally, we highlight the need to move beyond a warming fingerprint in studies of biogeographic responses by considering a more multifaceted view of climate, emphasizing local‐scale effects, and including a priori knowledge of relevant natural history for the taxa and regions under study.

Global Change Biology 20: 2841-2855

Keywords: biogeographic responses, California, climate change, climatic water balance, elevation, range shifts, temperature