Differences, arising from differences in gross primary production (GPP) model structures and driving forces, have fuelled arguments concerning interannual changes of GPP in China since 2000. To better investigate the interannual variability of GPP and its covariance with climate factors in China, this study adopted a multi‐model analysis based on three GPP models (i.e., Terrestrial Ecosystem Carbon flux model [TEC], Breathing Earth System Simulator model [BESS], and MOD17 GPP model). The results show that annual GPP in China increased by 0.021–0.057 Pg C year−1 from 2000 to 2015 attributable to atmospheric‐CO2 fertilization effects and favourable climate change, that is, increasing precipitation (Pr) and temperature (Ta). However, northern China and southern China had a large difference in the amplitude of these GPP changes; annual GPP increased by 0.017–0.039 Pg C year−1 in northern China but only 0.001–0.018 Pg C year−1 in southern China. Northern China and southern China occupy contrasting climate zones and this contrast produced different interannual variability of GPP through different mechanisms. Northern China has a dry climate with GPP changes sensitive to Pr. As a result, more Pr along with higher Ta in northern China produced the strong uptrend of GPP from 2000 to 2015. In contrast, southern China has a wet climate with its GPP sensitive to solar radiation and Ta. For the interval of 2000–2015, decreasing radiation plus drought exerted a negative influence on GPP in southern China. This study highlights the diverse mechanisms in which climate change affects GPP in dry and wet climate zones. A robust multi‐model analysis is preferred to reduce uncertainties arising from a single GPP model and its driving data.
Climate warming generally is expected to increase drought, but arguments about China's past drought trends persist. PDSIARTS, a revised self‐calibrating Palmer Drought Severity Index, was computed for China over 1982–2016 using satellite leaf‐area indices combined with monthly climate data interpolated from 2000 high‐density stations. Drought climatology was analysed against climate factors. The results show that temperature has increased at a rate of 0.38°C per decade (p < .001) in China in the past 35 years (1982–2016). However, over the same interval, China and the northern China region became wetter. PDSIARTS increased at a rate of 0.03 yr−1 (p < .001) across China during 1982–2016. The analogous increase of PDSIARTS in northern China was 0.05 yr−1 (p < .001). In China, the 5‐year interval from 2012 to 2016 was the wettest 5 years in the 35‐year interval. This arises from the coupled effects of decreased potential evaporation (Ep) and increased precipitation (Pr). The implication is that temperature increase does not necessarily indicate increased drought. A potential complication is that the 2015/16 El Niño event induced the highest Pr in southern China for 1982–2016, and northern China still had plentiful Pr in 2015/16, which further contributed to the wettest 2‐years (2015/16) during the past 35 years in the whole of China. This study highlights the joint impacts of Pr and Ep on the dry/wet changes and the possibility of extremely wet events in the warming future.
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