Some of my readers may not be aware that Nevada (actually the entire Great Basin) used to be quite a bit hotter and drier than it is now. Donald Grayson writes in Great Basin Natural History* that the Ruby Marshes, which currently make up the heart of the Ruby Lake National Wildlife Refuge near Elko, Nevada, was dry or nearly dry between about 6,800 and 4,500 years ago. Owens Lake dried up as well, while at Lake Tahoe trees were growing on land that is now 13 feet below the level at which the lake flows into the Truckee River. Summer temperatures at Pyramid Lake were around 9° F warmer than they are at present.
This is not an odd or controversial claim. The climate over much of the planet during the Middle Holocene period, sometimes called the Altithermal, was significantly warmer than today. Many places, including the Great Basin, were also quite a bit drier. So dry, in fact, that large portions of the Great Basin appear to have been completely abandoned by the people who had lived there during earlier periods.
Other instances of climate change have also impacted human societies in various ways. To pick just one example, the Medieval Climate Optimum had a profound impact throughout much of the western part of North America. Both the Puebloan peoples in the Southwest and the Chumash along the coast of California seem to have undergone significant social change during this time, although exactly how much of that was a direct response to climate stress will likely remain a subject of vigorous archaeological debate for some time to come. Thousands of miles to the southeast, along the west coast of South America, Michael Moseley, in The Incas and Their Ancestors: The Archaeology of Peru, interprets much of the cultural development in this part of the world as a series of responses to climactic stress. Many more examples could be given, but I think this is enough to make the point.
Understanding relationships between human societies and their surrounding natural environments has been a major focus in archaeology at least since the advent of processualism in ca. 1958. It therefore seems more than a little bit strange that archaeologists have not been major participants in current debates about climate change. Of course, I’m well aware that a few of the most shrill voices out there have already decided, usually for ideological reasons, what must be done. Those people have no real desire to hear from anybody except other true believers. But I think they are very much a minority (although a loud one). For the rest of the crowd, those who seriously want to understand what is going on and, just as importantly, make the best possible decisions about what, if anything, should be done, I think archaeology has the potential to offer some critical insights about adaptive strategies that have been used in the past.
I have a lot more to say about this, but it’s dinner time and I’m hungry, so it will have to wait until a future post.