Expansion of the Sahara Desert and shrinking of frozen land of the Arctic - PubMed (original) (raw)
Expansion of the Sahara Desert and shrinking of frozen land of the Arctic
Ye Liu et al. Sci Rep. 2020.
Abstract
Expansion of the Sahara Desert (SD) and greening of the Arctic tundra-glacier region (ArcTG) have been hot subjects under extensive investigations. However, quantitative and comprehensive assessments of the landform changes in these regions are lacking. Here we use both observations and climate-ecosystem models to quantify/project changes in the extents and boundaries of the SD and ArcTG based on climate and vegetation indices. It is found that, based on observed climate indices, the SD expands 8% and the ArcTG shrinks 16% during 1950-2015, respectively. SD southern boundaries advance 100 km southward, and ArcTG boundaries are displaced about 50 km poleward in 1950-2015. The simulated trends based on climate and vegetation indices show consistent results with some differences probably due to missing anthropogenic forcing and two-way vegetation-climate feedback effect in simulations. The projected climate and vegetation indices show these trends will continue in 2015-2050.
Conflict of interest statement
The authors declare no competing interests.
Figures
Figure 1
The Sahara Desert (SD) extent and boundary change based on climate and vegetation indices. (a) The Northern Africa climate zones averaged over 1950–2015. SD southern boundary changes based on climate index from (b) observation and (c) CFS/SSiB4 simulation during 1950–2015, and (d) CFS/SSiB4 simulation during 2015–2050. Observed and simulated (e) time series and (f) trend of SD extent defined by climate and vegetation indices. The error bars in (f) indicate one standard deviation due to the LAI based non-vegetation criterion range of 0.08–0.12 m2/m2. * in (f) indicates the value with significant level at p < 0.01 (Mann-Kendall test). Figure including maps in (a–d) are created by NCL (version 6.6.2,
).
Figure 2
The Arctic Tundra-Glacier (ArcTG) extent and boundary change based on climate index. (a) The Arctic climate zones averaged over 1950–2015. ArcTG boundary changes based on climate index from (b) observation and (c) CFS/SSiB4 simulation during 1950–2015, and (d) CFS/SSiB4 simulation during 2015–2050. Figures including maps in (a–d) are created by NCL (version 6.6.2,
).
Figure 3
The Arctic Tundra-Glacier (ArcTG) extent and boundary change based on vegetation index and comparison. Changes of ArcTG based on CFS/SSiB4 simulated vegetation index during (a) 1950–2015 and (b) 2015–2050. Observed and simulated ArcTG extent (c) time series and (d) trends based on climate and vegetation indices. * in (d) indicates the value with significant level at p < 0.01 (Mann-Kendall test). Figures including maps in (a) and (d) are generated by NCL (version 6.6.2,
).
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