Generalized additive model was applied to explore the effect of temperature, humidity and diurnal temperature range on the daily death counts of COVID-19. There were 2299 COVID-19 death counts in Wuhan during the study period. A positive association with COVID-19 daily death counts was observed for diurnal temperature range (r = 0.44), but negative association for relative humidity (r = −0.32). In addition, one unit increase in diurnal temperature range was only associated with a 2.92% (95% CI: 0.61%, 5.28%) increase in COVID-19 deaths in lag 3. However, both 1 unit increase of temperature and absolute humidity were related to the decreased COVID-19 death in lag 3 and lag 5, with the greatest decrease both in lag 3 [−7.50% (95% CI:
Owing to a lack of available long-term climatic records, data related to past climatic variability throughout the Tibetan Plateau remains limited. In this study, we found that Qilian juniper tree growth was significantly and positively correlated (p < 0.001) to yearly mean temperatures in the northeastern margin of the Tibetan Plateau. We developed an annual mean temperature reconstruction from year 1740 CE based on growth-climate relationships in the study area. Our reconstruction accounted for 53.9% of total variance from 1956 to 2012 (the calibration period). Through this reconstruction, we were successfully able to capture recent abrupt climate change events that generally agreed with other temperature-sensitive tree-ring reconstructions on both regional and hemisphere scales under a decadal timescale. Periods from 1820 to 1830, 1855 to 1890, and 1960 to 1985 CE corresponded to cold periods in the reconstruction, while the 1740s and periods from 1795 to 1815 and from 1990 to 2012 CE corresponded to relatively warm periods. We also detected increased interannual change variability in annual mean temperatures since the 1980s, which could be related to increasing variability in the East Asian winter monsoon as well as the rapid climate warming that has occurred since this time. From these reconstructed temperatures, we were successfully able to capture the occurrences of large volcanic events in China as well as five historic volcanic events outside China that had global implications on climate variability and that resulted in planetary cooling during the period from 1740 to 2012 CE. This in turn suggested that these volcanic events would have had short-lived impacts (approximately from 1 to 3 years) on temperature variation in the study area. The aim of this study was to provide a perspective in which to explore the mechanisms that simultaneously influence tree rings and climate.
As an important Tibetan medicine and a secondary protected plant in China, Pomatosace filicula is endemic to the country and is mainly distributed in the Qinghai–Tibet Plateau (QTP). However, global climate change caused by greenhouse gas emissions might lead to the extinction of P. filicula. To understand the potential spatial distribution of P. filicula in future global warming scenarios, we used the MaxEnt model to simulate changes in its suitable habitat that would occur by 2050 and 2070 using four representative concentration pathway (RCP) scenarios and five global climate models. The results showed that the QTP currently contains a suitable habitat for P. filicula and will continue to do so in the future. Under the RCP2.6 scenario, the suitable habitat area would increase by 2050 but shrink slightly by 2070, with an average reduction of 2.7%. However, under the RCP8.5 scenario, the area of unsuitable habitat would expand by an average of 54.65% and 68.20% by 2050 and 2070, respectively. The changes in the area of suitable habitat under the RCP4.5 and RCP6.0 scenarios were similar, with the unsuitable area increasing by approximately 20% by 2050 and 2070. Under these two moderate RCPs, the total suitable area in 2070 would be greater than that in 2050. The top three environmental factors impacting the habitat distribution were altitude, annual precipitation (BIO12) and annual temperature range (BIO7). The cumulative contribution rate of these three factors was as high as 82.8%, indicating that they were the key factors affecting the distribution and adaptability of P. filicula, P. filicula grows well in damp and cold environments. Due to global warming, the QTP will become warmer and drier; thus, the growing area of P. filicula will move toward higher elevations and areas that are humid and cold. These areas are mainly found near the Three-River Region. Future climate change will aggravate the deterioration of the P. filicula habitat and increase the species’ survival risk. This study describes the distribution of P. filicula and provides a basis for the protection of endangered plants in the QTP.
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