Climatology and meteorology studies in the Yucca Mountain area have resulted in the following key observations and conclusions: • The present-day arid climate of the Yucca Mountain area can be understood in terms of global-scale atmospheric circulation and regional to-local physiographic features. In general terms, the area is under the influence of mid-latitude westerly winds and associated storm systems during the cool part of the year and and is under the influence of moist air advected from the eastern tropical Pacific Ocean and Gulf of California during the summer. Temperature and precipitation data from Nevada regions 3 and 4 (southern Nevada) between 1895 and 1998 suggest a mean annual temperature of 13.4 °C and a mean annual precipitation of 125 mm at 1524 m (5,000 feet) elevation (Thompson et al. 1999 , Figures 13, 14, pp. 27-28). • Climate change over the past several hundred thousand years can be partially understood in terms of changes in these atmospheric circulation patterns, physiographic features, and predictable variations in the earth's orbital characteristics. • Past climate change can be timed using the Earth's orbital parameters: eccentricity and precession. This implies some past climate or aspects of past climate will recur in the future because future eccentricity and precession can be calculated. • Regional and local evidence indicates that the Yucca Mountain site has experienced, over the past several hundred thousand years, many different climate states, ranging from glacial to interglacial periods. Glacial and intermediate climate periods were periods of sustained greater effective moisture (commonly defined as precipitation minus evaporation, thus temperature is important) with greater infiltration and recharge than the present interglacial period. Although Yucca Mountain experienced glacial climates, it did not experience glaciation. • For the purposes of this report, long-term past climate proxy data were simplified into four climate states (interglacial, monsoon, intermediate, glacial), each with a different level of effective moisture. Climate states typical of the past 500,000 years are thought likely to reoccur in the next 500,000 years. These climate states, their duration, and magnitude are based on the assumptions and methods used and discussed herein. • Six glacial stages are predicted to occur over the next 500,000 years. They may range between 8,000 and 38,000 years in duration and encompass about 19% (95,000 years) of the next 500,000 years. These glacials will vary in magnitude, ranging from relatively warm and wet to cold and dry. • Future glacial period upper bound (most conservative) estimates for mean annual temperature and mean annual precipitation in the Yucca Mountain area are 0°C and 513 mm, respectively. Glacial period lower bound estimates for mean annual temperature and mean annual precipitation in the Yucca Mountain area are approximately 9°C and 430 mm, respectively. Other published estimates of past temperature and precipitation for the Yucca Mountain area and western Great Basin during glacial periods range from 5-15° C colder than today and precipitation from 1.4 to 2.6 times modern. • The intermediate and intermediate/monsoon climate states are estimated to encompass over 68% of the next 500,000 years (>340,000 years). Intermediate climate state bounds range from approximately 9 to 10°C and 430 to 200 mm per year. • Monsoon climate states, which tend to occur between interglacial and intermediate climate states, are estimated to occur 3% of the time over the next 500,000 years during the intermediate/monsoon climate state. Monsoon climate state bounds range from about 13 to 17°C and 125 to 400 mm per year. • Interglacial (e.g. modern) climate is the warmest and driest of all climate states. This climate state has been dominant in the Yucca Mountain area, with some variation, for only the last 7 to 8 ka. The interglacial climate state is estimated to occur about 13% (65,000 years) of the time during the next 500,000 years. Mean annual temperature and precipitation are estimated to be about 13°C and 125 mm per year. • Present-day meteorological stations were selected to represent the four past climate state.
Climate; Climatic changes; Nevada – Yucca Mountain; Paleoclimatology
Climate | Meteorology | Oceanography and Atmospheric Sciences and Meteorology
Sharpe, S. E.,
Smiecinski, A. J.
Climate: Past, present, and future.
Available at: http://digitalscholarship.unlv.edu/yucca_mtn_pubs/69