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Evidence that Alpine Grasslands are Coping Well with Rising Temperatures

Paper Reviewed
Huang, N., He, J.-S., Chen, L. and Wang, L. 2018. No upward shift of alpine grassland distribution on the Qinghai-Tibetan Plateau despite rapid climate warming from 2000 to 2014. Science of the Total Environment 625: 1361-1368.

Some people are concerned that Earth's temperature will rise so high and so fast in response to predicted CO2-induced global warming that many alpine plant and animal species will soon be mere memories, because of the assumption that after being forced to migrate to the tops of the mountains upon which they now reside at lower levels, there will be nowhere else for them to go in a vertical direction but to the sorry state of extinction.

Such has long been the siren call of James Hansen, former Director of NASA's Goddard Institute for Space Studies, who in testimony given to the Select Committee of Energy Independence and Global Warming of the United States House of Representatives in 2008, declared that "climate is nearing dangerous tipping points," that if CO2 emissions follow a business-as-usual scenario, "alpine species will be pushed off the planet," and that "we have used up all slack in the schedule for actions needed to defuse the global warming time bomb," adding that his conclusions "have a certainty exceeding 99 percent."

But is this really so? Are rising temperatures and atmospheric CO2 concentrations driving alpine species toward extinction? Ten years have now elapsed since Hansen issued his siren call and a new paper by Huang et al. (2018) is pouring some cold water on his hot temperature/alpine extinction claim.

Recognizing that temperatures on the Qinghai-Tibetan Plateau -- the world's highest and largest plateau -- have experienced a rate of warming that has exceeded that observed for all other areas of the same latitude in recent decades, it was their hypothesis that alpine grasslands in this region would surely show recent upward shifts, marching ever so closer to that point of no return theorized by Hansen on the path toward being pushed off the planet. So, to examine this hypothesis, the four Chinese scientists performed field experiments and analyzed remotely-sensed normalized difference vegetation index (NDVI) data across six elevational transects on the Qinghai-Tibetan Plateau to determine trends in alpine grassland distribution over the period 2000 to 2014.

The results of their study indicate that during the period of examination there was no trend in precipitation across the study region of the Plateau. However, the observed rate of warming across the transects amounted to approximately 0.4°C per decade, which, in the authors' estimation, should have driven an equivalent altitude grassland upslope increase of around 70 meters. Analysis of the NDVI data, on the other hand, yielded results that Huang et al. describe as "inconsistent with expectations related to climate warming on the Qinghai-Tibetan Plateau," which is a rather nice way of admitting they failed to agree with their hypothesis. Rather, the data, in the authors' words, "provided compelling evidence that alpine grassland distribution on the Qinghai-Tibetan Plateau has not increased in altitude from 2000 to 2014, during which time the temperature has increased." Furthermore, they note that "across all transects, there was no general increase in aboveground biomass towards higher elevations."

The plain and simple interpretation of the above findings is that, despite a recent warming rate that is greater than that averaged for all of the Northern Hemisphere, there was still no shift in the range of the alpine grasslands measured by Huang et al. These findings, therefore, along with others we have written about on our website on this topic, totally contradict the predictions of climate alarmists like James Hansen, who continue to push forth the false storyline that global warming is pushing alpine species off the planet and toward extinction. That narrative simply is not true.

Posted 21 September 2018