Pliocene environments and climates in the western United States
Pliocene environments and climates in the western United States
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DOI：
10.1016/0277-3791(91)90013-k
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发表时间：
1991
影响因子：
4
通讯作者：
R. S. Thompson
中科院分区：
文献类型：
--
作者：
R. S. Thompson
美国西部的现有证据表明，上新世早期和中期（距今2.4 Ma之前）的气候比现在的季节性更少（更平稳），而且通常更潮湿。沿着太平洋海岸，夏季干旱没有今天那么明显。在太平洋西北部内陆地区，降雨量更为充足，高平原的大部分地区冬季气温温和。在西北部内陆，在2004年后开始出现干燥的趋势，尽管在此之后可能有短暂的相对潮湿的条件。在2.5或2.4-2.0 Ma之间的时期，整个美国西部都比上新世更早的时期更干燥，而且在许多地区明显更冷，尽管在堪萨斯北部出现的陆龟可能表明在这段时间内间歇性的无霜条件。2.0Ma以后，气候变得温暖湿润，陆地资料的气候变化趋势与北太平洋和氧同位素记录的全球冰川波动相一致。全球气候模式（GCM）对晚新生代隆升造山作用区域效应的模拟，与上新世与现代气候差异的性质、方向和幅度基本雅阁。
The available evidence from the western United States suggests that the climate of the Early and Middle Pliocene (prior to ∼2.4 Ma) was less seasonal (more equable) and generally more humid than now. Along the Pacific coast, summer drought was less pronounced than today. In the interior of the Pacific Northwest rainfall was more abundant and mild winter temperatures prevailed across much of the High Plains. In the Northwestern interior, a trend toward drier conditions began after ∼4 Ma, although there may have been short periods of relatively humid conditions after this time. The period between 2.5 or 2.4-2.0 Ma was drier than earlier in the Pliocene throughout the American West, and apparently colder in many regions, although the occurrence of land tortoises as far north as Kansas may indicate intermittent frost-free conditions during this interval. After ∼2.0 Ma conditions became warmer and more humid.The general climatic trends in the terrestrial data parallel fluctuations seen in North Pacific and in Oxygen Isotopic records of global glacial fluctuations. Global Climate Model (GCM) simulations of the regional effects of Late Cenozoic uplift and mountain-building are generally in accord with the nature, direction, and amplitude of differences between Pliocene and modern climates.