Global analysis of the specific climate periods

Bioclimatic variables are chief components of models targeting climate change effects on the potential distribution of species and other ecological phenomena (e.g., vegetation types). Predicted distributions depend on the values of the bioclimatic variable (e.g., temperature of the wettest quarter of the year). At the same time, a shift in period underlying the variable calculation (e.g., wettest quarter of the year) easily remains hidden, even though the ecological meaning of these variables depends heavily on it. A study recently published in the D1-ranked scientific paper “Global Change Biology” uncovers how the within-year position of these specific climate periods (SCPs) are expected to shift in a global context in reaction to climate change according four future time periods, four scenarios, and four global climate models. The research was conducted by Ákos Bede-Fazekas, assistant professor in our department and Imelda Somodi, senior research fellow at the Centre for Ecological Research. The scientists found ample examples of SCP shifts exceeding 2 months, with 6-month shifts being predicted as well. Many areas in the tropics are expected to experience both temperature and precipitation-related shifts, but precipitation-related shifts are abundantly predicted for the temperate and arctic zones as well. The combined shifts at the Equator reinforce the likelihood of the emergence of no-analogue climates there. The shifts become more pronounced as time and scenario progress, while global climate models could not be ranked in a clear order in this respect. For most SCPs, the modeler's decision on the global climate model was the least important, while the choice of time period was typically more important than the choice of scenario. Future predictive distribution models should account for SCP shifts and incorporate the phenomenon in the modeling efforts.