Abstract
Abstract. Closed basins, mainly located in subtropical and temperate drylands, have experienced alarming declines in water storage in recent years. An assessment of long-term hydroclimate change in those regions remains unquantified at a global scale as of yet. By integrating lake records, PMIP3–CMIP5 simulations and modern observations, we assess the wet–dry status of global closed basins during the Last Glacial Maximum, mid-Holocene, pre-industrial, and 20th and 21st century periods. Results show comparable patterns of general wetter climate during the mid-Holocene and near-future warm period, mainly attributed to the boreal summer and winter precipitation increasing, respectively. The long-term pattern of moisture change is highly related to the high-latitude ice sheets and low-latitude solar radiation, which leads to the poleward moving of westerlies and strengthening of monsoons during the interglacial period. However, modern moisture changes show correlations with El Niño–Southern Oscillation in most closed basins, such as the opposite significant correlations between North America and southern Africa and between central Eurasia and Australia, indicating strong connection with ocean oscillation. The strategy for combating future climate change should be more resilient to diversified hydroclimate responses in different closed basins.
Highlights
A great number of observations in the last 100 years show that the Earth’s climate is experiencing significant change characterized by global warming (Hansen et al., 2010; Trenberth et al, 2013; Dai et al, 2015; Huang et al, 2016; Li et al, 2018), which is unequivocally induced by the increase in concentrations of greenhouse gases according to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2013)
In the North and South American continents, almost all closed basins experience a wetter Last Glacial Maximum (LGM) compared to the MH status, and the same situations exist in some closed basins of the eastern Mediterranean, Tibetan Plateau and Australia
This study presents a new compilation of lake records and analyses of hydroclimate change at different timescales in global closed basins
Summary
A great number of observations in the last 100 years show that the Earth’s climate is experiencing significant change characterized by global warming (Hansen et al., 2010; Trenberth et al, 2013; Dai et al, 2015; Huang et al, 2016; Li et al, 2018), which is unequivocally induced by the increase in concentrations of greenhouse gases according to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2013). According to Held’s hypothesis, rising atmospheric humidity will cause the existing patterns of atmospheric moisture divergence and convergence to intensify, thereby making effective precipitation more negative in the drylands and more positive in the tropics, referred to as the “dry gets drier, wet gets wetter” (DGDWGW) paradigm (Held and Soden, 2006; Hu et al, 2019) This mechanism may be more complex regionally, especially over terrestrial environments, where wet–dry pattern changes over the past decades and in future projections do not follow the proposed intensification trend (Greve et al 2014; Roderick et al 2014). To accurately project future terrestrial hydroclimatic changes, past climates may aid in understanding the regional nuances of the DGDWGW effect (Lowry and Morrill, 2019). Quade and Broecker (2009) have verified Held’s hypothesis by taking the Last Glacial Maximum (LGM) as a reverse analogue for modern global warming and point out that the hydroclimate changes in subtropical regions are more complicated
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