The timing and duration of the coldest period in the last glacial stage, often referred to as the last glacial maximum (LGM), has been observed to vary spatially and temporally. In Australia, this period is characterised by colder, and in some places more arid, climates than today. We applied Monte-Carlo change point analysis to all available continuous proxy records covering this period, primarily pollen records, from across Australia (n = 37) to assess this change. We find a significant change point occurred (within uncertainty) at 28.6 ± 2.8 ka in 25 records. We interpret this change as a shift to cooler climates, associated with a widespread decline in biological productivity. An additional change point occurred at 17.7 ± 2.2 ka in 24 records. We interpret this change as a shift towards warmer climates, associated with increased biological productivity. We broadly characterise the period between 28.6 (± 2.8) – 17.7 (± 2.2) ka as an extended period of maximum cooling, with low productivity vegetation that may have occurred as a combined response to reduced temperatures, lower moisture availability and atmospheric CO2. These results have implications for how the spatial and temporal coherence of climate change, in this case during the LGM, can be best interrogated and interpreted.

中文翻译：

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澳大利亚末次冰期环境变化时间的大陆视角

已观察到末次冰期最冷时期（通常称为末次冰期最大值（LGM））的时间和持续时间在空间和时间上有所不同。在澳大利亚，这一时期的特点是气候比今天更冷，在某些地方更干旱。我们将 Monte-Carlo 变化点分析应用于涵盖这一时期的所有可用连续代理记录，主要是来自澳大利亚 (n = 37) 的花粉记录，以评估这种变化。我们发现在 25 条记录中发生显着变化点（在不确定范围内）为 28.6 ± 2.8 ka。我们将这种变化解释为向凉爽气候的转变，与生物生产力的普遍下降有关。在 24 条记录中，一个额外的变化点发生在 17.7 ± 2.2 ka。我们将这种变化解释为气候变暖的转变，与提高生物生产力有关。我们将 28.6 (± 2.8) – 17.7 (± 2.2) ka 之间的时期广泛描述为最大冷却的延长时期，低生产力的植被可能是对温度降低、水分可用性降低和大气 CO2 的综合反应2. 这些结果对于如何最好地询问和解释气候变化的空间和时间一致性（在这种情况下是在 LGM 期间）具有重要意义。