In Science, a study by I-Ching Chen and colleagues shows that organisms are shifting toward the poles almost three times faster than previously estimated: at 16.9 km per decade (median rate). Species are also shifting upslope twice as fast previous estimates indicated, moving at a median rate of 11.0 m per decade.
In Nature, Joshua Tewksbury and colleagues emphasise a major reason for the faster shifts: the different time span used for Chen’s study, compared to previous studies on range shifts, and the increased warming rate. Warming from 1970 to the present is four times the rate of that from 1900 to 1970. “Because the rate of climate change is expected to increase further in the future, we may expect upward revisions in the rates observed by Chen and colleagues,” write Tewksbury and colleagues.
Does this mean life is keeping up with climate change? The Science study looked at dozens of reports of range shifts, many of them from the past eight years. For latitudinal range shifts, there were nearly as many instances (nine) of species moving as fast as expected as there were instances where species are lagging behind (11).
However, for elevational range shifts a very different picture emerges. Despite much shorter distances required to track climate change, it found only two instances of species keeping up with warming, and 28 instances where they appear to be lagging behind. There may be many reasons for the lags: complexity of mountain terrain and climate, for example, or that suitable locations may actually lie on other, distant mountain peaks.
Looking specifically at birds, Chen and colleagues found that they are making latitudinal shifts at a rate slightly greater than expected, but are lagging most in their elevational responses.