Montana State (West), USA

This is part of the Regional Summary series at www.appinsys.com/GlobalWarming

This document provides a regional study of the western part of Montana State, USA. Only temperature and precipitation stations that have data from prior to 1930 and after 1995 are included in this study, since climate studies are only valid by including long-term data (the IPCC includes stations that have data from 1961 to 1990, since their intent is not long-term climate study, but only to show recent warming).

The following figure shows the temperature trends (mean annual temperature) for long-term stations in western Montana. No long-term warming is observed.

A 2006 paper by scientists at Montana State University and the U.S. Geological Survey (Pederson, G.T., S.T. Gray, D,B. Fagre, and L.J. Graumlich. 2006. “Long-Duration Drought Variability and Impacts on Ecosystem Services: A Case Study from Glacier National Park, Montana”. Earth Interactions, 10, Paper No. 4.) examined drought history for Glacier National Park and the surrounding area, using tree ring proxies. The following figure is from their paper. The top of the two plots shows the observed and reconstructed mean summer soil moisture deficit over the past century, while the lower plot shows us the reconstructed drought levels back to 1540. There is no correlation between drought and CO2.

Above: Glacier National Park Drought: (A) Comparison of the observed and reconstructed mean summer deficit records for the 1900–2000 calibration period. (B) Mean centered reconstructed mean summer deficit (blue line) and smoothed values (red line) spanning 1540–2000. (C) Decadal-scale drought regimes exhibiting the significant step changes in the mean.

The same study provides the following figure showing the decreasing area of the Sperry Glacier over the available timeframe of observations (left). The graph (right) shows the glacier area versus year.

The following figure shows annual total precipitation data for three locations in western Montana. Although there has been recent drought in some areas (see Kalispell and Cut Bank below), the decadal trend does not have any correlation to CO2.