Cenozoic Mountain Building and Climate Evolution

Abstract

Climate and land surfaces are intimately linked. This manuscript provides an introduction to mountain and climate interactions, with a particular focus on how temperature, atmospheric circulation and precipitation change with surface uplift. Although the timing and mechanisms of the South American Andes and North American Cordillera uplift are uncertain, both orogens have a first- order control on regional climate. With surface uplift, climate models generally suggest enhanced windward precipitation, orographic deflection of prevailing winds and decreased surface temperatures. However, the details of these responses are unique to each orogen and dependent on geographic position. In South America, Andean uplift led to a shift in prevailing winds from a Pacific source to an Atlantic source, development of a low-level jet along the eastern flank, increased moisture transport from the tropics and enhanced convective rainfall along the Andean lowlands and eastern flank. In North America, topographic blocking enhanced windward precipitation and initiated monsoonal conditions along the eastern flank, modified atmospheric circulation to create a pronounced trough-and-ridge pattern over western North America and formed a rain shadow over central North America. These changes add to the mechanistic understanding of regional Cenozoic climate and environmental change.