20th century temperature data indicate that the "Last Best Place" is heating up
Pederson GT, Graumlich LJ, Kipfer T, Caruso CJ, Fagre DB. 2006. 20th century temperature data indicate that the "Last Best Place" is heating up. USGS, Montana State University
The people of Montana take a certain pride in enduring, and even enjoying, long, cold winters. That said, in the dead of winter the prospect of global warming is greeted by many with happy anticipation. While speculation about trends in Montana climate abounds, little scientific effort has been brought to bear on the topic. In this poster, we report on 20th-century trends in temperature extremes for nine Historical Climate Network stations with at least 100 years of record in the mountains of western Montana. What are extreme climate events? Weather conditions are highly variable in Montana. In seeking to detect changes in extreme climate events, we defined “extreme climate events” as large areas experiencing unusual climate values over a long period of time. More specifically, we used daily weather records to determine number of days per year exceeding three key thresholds (-17.8ºC (0ºF), 0ºC (32ºF), and 32.2ºC (90ºF); following Easterling et al. 2000). Why focus on temperature extremes? In Montana, episodes of extreme heat or cold are often associated with major impacts on human health, agricultural production, wildfire, and consumer energy demands (Easterling et al. 2000). Some of these impacts may be socially positive (e.g., reduction in the number of heating degree days). Some of these impacts have the potential to disrupt human livelihoods and local economies (e.g., large wildfires, Westerling et al. 2006). What causes extreme temperature events? Episodes of extreme climate events are associated with longterm changes in drivers of regional climate change in the American West, particularly Pacific Ocean temperature patterns such as El Niño – Southern Oscillation (ENSO) variability. Trends towards extreme warmth in recent decades provide evidence that Montana’s climate may be warming in synchrony with the overall climate of the Earth. Increasingly, scientific evidence indicates that approximately global temperature rise of 0.6ºC (1.1ºF) over the 20th century can be directly attributed to the accelerated accumulation of greenhouse gases in the atmosphere (Figure 1; IPCC 2001, Hansen et. al. 2005).