Unveränderte Höhenlage: Alpines Grasland im Himalaya von Klimaerwärmung unbeeindruckt

Die globale Temperatur steigt. In der ganzen Welt? Nein. Ein unbeugsames Land trotzt dem Trend und weigert sich standhaft, sich zu erwärmen. Wir sprechen von den Vereinigten Arabischen Emiraten. Basarir et al. 2017 schauten sich die Zahlen an und konnten für die Zeit 2003-2015 nur einen Hiatus feststellen:

Trend Detection in Climate Change Indicators Using Non-Parametric Statistics: A Case Study of Abu Dhabi, United Arab Emirates
This study focuses on detecting trends for climate change indicators, such as average monthly temperature, rainfall, humidity, and wind speed for fourteen stations located between Al Ain and Abu Dhabi cities of the United Arab Emirates. Mann-Kendall non-parametric test was run on monthly time series data for the period 2003-2015 with consideration of seasonality. Significant increasing/decreasing trends in rainfall (for four stations), humidity (for six stations), and wind speed (for nine stations) were detected while no significant trend was observed in temperature for all stations.

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Sie kennen die Baumgrenze oberhalb der es den Bäumen zu kalt wird. Die Baumgrenze ist daher auch ein guter Klimaindikator. Wenn es kälter wird, sinkt die Baumgrenze, und wenn es wärmer wird, klettert die Baumgrenze in größere Höhenlagen. Eine Forschergruppe um Huang et al. 2018 untersuchte nun die Höhenentwicklung des alpinen Graslandes im Himalaya mithilfe von Satellitenbildern. Interessanterweise veränderte sich die Höhenlage zwischen 200-2014 in keinster Weise, obwohl die Temperaturen anstiegen. Abstract:

No upward shift of alpine grassland distribution on the Qinghai-Tibetan Plateau despite rapid climate warming from 2000 to 2014
The distributions of many species show climate-driven shifts towards higher elevations, but evidence for elevational shifts is scarce for the alpine grasslands on the Qinghai-Tibetan Plateau. The upward shift of alpine grassland distribution from 2000 to 2014 was assessed with field measurements and satellite remote sensing data obtained across six elevational transects on the Qinghai-Tibetan Plateau. The aboveground biomass (AGB) of alpine grasslands varied with altitude and its data produced a bell-shaped curve. This was mainly due to the elevational dependency of climate change at the surface (i.e., producing drier climate at low elevations and wetter climate at middle elevations). The normalized difference vegetation index (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) exhibited a positive exponential relationship with the AGB of alpine grasslands. Overall, MODIS NDVI initially increased, then peaked at median altitude sites, then decreased with altitude on each elevational transect. MODIS NDVI at the upper limit of alpine grassland distribution did not show a significant increasing trend from 2000 to 2014, even though land surface temperature increased and precipitation remained approximately constant. High spatial resolution Landsat data supported this result. Further analyses of MODIS NDVI at all other sites found no general increase in AGB towards higher elevations. The results suggest that the distribution of alpine grasslands on the Qinghai-Tibetan Plateau did not show an upward shift despite rapid climate warming having occurred from 2000 to 2014.

Siehe auch Kommentierung des Papers auf CO2 Science.