Paper Reviewed
Campbell, T.K.F., Lantz, T.C., Fraser, R.H. and Hogan, D. 2020. High Arctic vegetation change mediated by hydrological conditions. Ecosystems doi.org/10.1007/s10021-020-00506-7.

According to Campbell et al. (2020), "understanding high Arctic vegetation change is important because it will impact wildlife habitat and ecological feedbacks to the climate system." And thus they went on to examine how this key parameter has changed over the period 1984-2014 within the Banks Island Migratory Bird Sanctuary on Banks Island, the westernmost island in the Canadian Arctic Archipelago, Northwest Territories, Canada. To accomplish this objective, the four Canadian researchers analyzed satellite images to produce a record of Tasseled Cap Greenness (TCG), which index "uses the difference between near-infrared and visible bands, making it suitable for measuring green vegetation" and which is "strongly correlated with Normalized Difference Vegetation index (NDVI)."

The results of the analysis can be summarized in the figure below. Approximately 0.3% of all pixels (67.58 km²) experienced vegetative decline (i.e., browning) across the study period, 20% (3943.39 km²) showed no significant trend in TCG, and a whopping 80% (15,628.08 km²) exhibited a significant positive TCG trend (i.e., greening) from 1984-2014." It was also reported that this vegetative improvement was indicative of new or shifting species, but rather the product of "increases in biomass of the dominant vegetation in upland and lowland habitats."

With respect to the cause of this overwhelming enhancement of vegetative productivity, Campbell et al. say "the widespread nature of these changes suggests that they are linked to recent increases in air temperature, but a strong association between the magnitude of greening and flow accumulation, long-term changes in moisture, and slope also suggests that observed greening is being mediated by hydrological conditions." It is also quite likely that the greening trends are largely the product of the modern rise in atmospheric CO2, which relationship the authors did not examine. However, as demonstrated in numerous links found in our Subject Index under the heading Greening of the Earth, more and more studies are confirming the growth-enhancing, water-saving and stress-alleviating effects of rising atmospheric CO2 are responsible for the lion's share of recent greening trends. Regardless of the cause, one thing is for sure, the rise in atmospheric CO2 and temperature have not been harmful in contrast to climate alarmist predictions.

Figure 1. (Panel A) Significant changes in vegetative productivity based on Tasseled Cap Greenness (TCG) trend slopes (p < 0.05) across Banks Island Migratory Bird Sanctuary No. 1. (Panel B) Enlarged inset showing an alluvial terrace adjacent to the Bernard River. (Panel C) Enlarged inset showing an upland area northeast of the Egg River Snow Goose nesting colony. (Panel D) The proportion of pixels with significant positive (greening) or negative (browning) TCG trend slopes (p < 0.05) in each habitat type; pixels were classified as stable (gray) if there was no significant trend. Habitat types include: dry-mesic tundra (MT), hummocky tundra (HT), dwarf shrub-herb tundra (ST), lowland pond complex (PC), wet meadow (WM), moist meadow (MM), and degraded lowland (DL). Source: Campbell et al. (2020).