Spatio-Temporal Variation of Drought within the Vegetation Growing Season in North Hemisphere (1982–2015)

Abstract

Drought disasters jeopardize the production of vegetation and are expected to exert impacts on human well-being in the context of global climate change. However, spatiotemporal variations in drought characteristics (including the drought duration, intensity, and frequency), specifically for vegetation areas within a growing season, remain largely unknown. Here, we first constructed a normalized difference vegetation index to estimate the length of the growing season for each pixel (8 km) by four widely used phenology estimation methods; second, we analyzed the temporal and spatial patterns of climate factors and drought characteristics (in terms of the Standardized Precipitation Evapotranspiration Index (SPEI)), within a growing season over vegetation areas of the northern hemisphere before and after the critical time point of 1998, which was marked by the onset of a global warming hiatus. Finally, we extracted the highly drought-vulnerable areas of vegetation by examining the sensitivity of the gross primary production to the SPEI to explore the underlying effects of drought variation on vegetation. The results revealed, first, that significant (p < 0.05) increases in precipitation, temperature, and the SPEI (a wetting trend) occurred from 1982 to 2015. The growing season temperature increased even more statistically significant after 1998 than before. Second, the duration and frequency of droughts changed abruptly and decreased considerably from 1998 to 2015; and this wetting trend was located mainly in high-latitude areas. Third, at the biome level, the wetting areas occurred mainly in the tundra, boreal forest or taiga, and temperate coniferous forest biomes, whereas the highly drought-vulnerable areas were mainly located in the desert and xeric shrubland (43.5%) biomes. Our results highlight the fact that although the drought events within a growing season decreased significantly in the northern hemisphere from 1998 to 2015, the very existence of a mismatch between a reduction in drought areas and an increase in highly drought-vulnerable areas makes the impact of drought on vegetation nonnegligible. This work provides valuable information for designing coping measures to reduce the vegetative drought risk in the Northern Hemisphere.

Length of growing season is modulated by Northern Hemisphere jet stream variability

“…NHJ variability has been observed and is projected to increase due to anthropogenic warming (Mann et al ., 2018; Trouet et al ., 2018). Multi‐decadal trends of longer growing seasons, earlier onset, and/or delayed senescence attributed to warmer growing season temperatures (e.g., Schwartz et al ., 2013; Liu et al ., 2016b) and increased water availability (Zeng et al ., 2020) may be reduced as plants are forced to respond to increased interannual climate variations or decreased water availability. Indeed, warmer temperatures may increase the sensitivity of phenology to climate variability (Chen et al ., 2020).…”

Characterisation of Vegetation Response to Climate Change: A Review

“…Consequently, affecting certain structural characteristics of the world vegetation types and their associated functions in the earth-atmospheric system functioning, which are determined by the vegetation sensitivity response effect, productivity and distribution of plant species [22,52,60]. In general, global vegetation coverage has been noted to have undergone significant transformation, affecting species dynamics and grassland conditions [61,62]. The world's vegetation types including the native vegetation such as forests, grasslands and shrublands are adversely affected by land, topography and soil (land cover change, drainage and erosion potentials and decreased cohesion of residual plant) in response to environmental factors [63,64].…”

Quantifying the Spatio-Temporal Pattern Differences in Climate Change before and after the Turning Year in Southwest China over the Past 120 Years

“…The North Asian region from Siberia to Mongolia has shown the most drastic warming over the last hundred years, with the warming rate exceeding 2 • C/(100 a) [12,[15][16][17]19,20], and the global annual mean land surface temperature showing a more significant warming trend in the first 20 years of the new century; however, spatial differences have been more significant [21][22][23]. The situation described above has led to a further increase in the intensity and number of extreme weather events worldwide, resulting in accelerated glacial melting, significant cryospheric retreat, significant reductions in the quantity and acreage of snowpack, and rapid sea-level rise, altering the quantity and quality of rivers, lakes, and wetlands [6,[8][9][10][11]14,24] and ultimately affecting the distribution pattern of global precipitation [16,[25][26][27]. For example, mid-and high-latitude regions in the Northern Hemisphere, tropical regions, and subtropical regions in the Southern Hemisphere have shown a significantly increasing precipitation trend [25,26].…”

“…The situation described above has led to a further increase in the intensity and number of extreme weather events worldwide, resulting in accelerated glacial melting, significant cryospheric retreat, significant reductions in the quantity and acreage of snowpack, and rapid sea-level rise, altering the quantity and quality of rivers, lakes, and wetlands [6,[8][9][10][11]14,24] and ultimately affecting the distribution pattern of global precipitation [16,[25][26][27]. For example, mid-and high-latitude regions in the Northern Hemisphere, tropical regions, and subtropical regions in the Southern Hemisphere have shown a significantly increasing precipitation trend [25,26]. There has been a decreasing precipitation trend in the warm temperate climate regions and an increasing trend in the arid and polar climate regions [28].…”