In introducing their intriguing new paper, Lenoir et al. state that "several models using the IPCC climate-change scenarios to forecast impacts on biodiversity predict that many organisms risk extinction within the next century." However, they indicate that "these models were computed at a coarse spatial resolution (>>1 km²) and fail to capture spatial variability in temperature over tens or hundreds of meters," which latter phenomenon can, in their words, "potentially constitute an important buffer in ecosystem response to climate change," citing Ackerly et al. (2010). In fact, they note that topo-climatic variability may provide "micro-refugia where species might persist locally amidst unfavorable regional conditions," as described by Dynesius et al. (2009), Ashcroft (2010), Austin and Van Niel (2011) and Dobrowski (2011), simply "by shifting by as little as a few meters to neighboring locations with cooler conditions," such as "towards more polar-facing slopes with lower insolation or towards patches of wetter ground with higher heat-consuming evaporation," as has been described by Edwards and Armbruster (1989), Wesser and Armbruster (1991), Armbruster et al. (2007) and Ackerly et al. (2010).

Focusing on Northern Europe (53-82°N, 3-32°E), the 35 researchers compiled a comprehensive database of 42,117 fine-grained (<1000 m²) and geo-referenced plots of terrestrial vascular plant communities that encompassed a large array of vegetation types, including forests, scrublands, grasslands and moorlands, after which they combined all vegetation plots with Ellenberg et al. (1992) species-indicator growing-season temperatures that ranged from 1 (cold) to 9 (warm) with independent data on field records of plant community composition, as had previously been done by Karlsen and Elvebakk (2003), Karlsen et al. (2005) and Scherrer and Korner (2011), which procedure they describe as "an approach that is particularly well suited for predictive purposes."

And when (at last!) all was done, Lenoir et al. concluded that "fine-grained thermal variability over tens or hundreds of meters exceeds much of the climate warming expected for the coming decades," which led them to further conclude that "thermal variability within 1-km² units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains," while indicating once again that this variability in temperature "provides buffering to mitigate climate-change impacts."

Sherwood, Keith and Craig Idso

References
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