COS 37-3
Distributions of stable and non-analogous climate areas in the past and in the future in the world’s major continents
Understanding global patterns of stable and non-analogous climate areas at continental scale is critical for studying species distribution and historical range shifts, which has profound implications in biogeography, evolutionary ecology, biodiversity science and conservation. However, quantitative analysis in dealing with this problem is still lacking.
Here we present a preliminary analysis that describes the spatial patterns of stable and non-analogous climate areas in the past (21kBP, 6kBP) and in the future (in 2100 AD) based on predictions of seven general circulation models (GCMs). Firstly we downscaled the coarse resolution predicting results of monthly mean temperatures and precipitations into 10-minutes-resolution grids; and then applied these layers to calculate map layers of five essential bioclimatic variables, including temperature of the coldest month (T_cld), growing degree days (GDD), growing season aridity (Arid), precipitation seasonality (P_season) and temperature precipitation synchronicity (TP_syn). To quantify stable and non-analogous climates, thresholds at continental scale for each variable were derived from frequency distribution and standard deviation of that variable at present. Appling these thresholds to the corresponding past and future variables, we got classifications for each climatic variable. Finally, we merged the classifications into an integrated map.
Results/Conclusions
The spatial distributions of both the stable and the non-analogous climate areas contain divergent patterns, varying among bioclimatic variables and time periods of analysis. 1) Temperature-related variables (T_cld, GDD) contribute much more to non-analogous climate areas than other variables do, probably because of their directional trends. However, the effects varied between continent locations and time periods. For example, during warming period, non-analogous climate (exceptional warm) areas prevalently occurred in tropical areas of all continents except Antarctic. 2) Aridity (Arid) varied greatly at local scale but contributed little to non-analogous areas, which were derived from continental scale analysis. It did contribute significantly to unstable climate areas. P_season and TP_syn contributed still less to distributions of non-analogous climate areas than Arid did. 3) Different GCMs produced large locally incongruence in all precipitation-related variables. Surprisingly, this produced little overall pattern changes in stable and non-analogous climate areas at continental scale.
Our results confirmed that the directional change in temperature is the upmost important factor affecting world ecosystems and biodiversity at global and continental scales, and could also relieve, to some extent, the major concerns on the reliability of climate based biodiversity trend assessment caused by uncertainties in precipitation.