Cold weather locally belies threat posed by warming on a global scale

The mission of the Kootenai Climate Group is to help our community understand climate science, identify associated issues, and promote local and global solutions.

A good place to start is to understand the difference between weather and climate. Weather describes short term, day-to-day conditions like temperature, humidity, precipitation, cloudiness and wind. Climate describes how weather behaves over seasons, years, centuries and millennia.

In any location there will be seasons — or years — that are colder or warmer, drier or wetter, but climate is characterized by long term averages. The colder than average conditions we experienced this year were just a variation on the cooler side of average. Our brief cold snaps this fall, or even an entire cool year, will not tell us what the trend of the average temperature is over time and fails to characterize long term trends in our climate.

Using the data from thousands of weather stations around the earth and satellite remote sensing, scientists are able to determine the annual global average temperature. Examination of temperature data going back to the late 1800s conclusively demonstrates the earth has been getting warmer. The last five years have been the hottest five years ever recorded.

The principle cause of accelerated global warming right now is the increase in greenhouse gas emissions from human activities. These gases are trapping more solar energy in our atmosphere, enhancing a process known as the greenhouse effect. This process is much like how sunlight streaming through a window is trapped and warms a room.

The greenhouse gases of primary concern are carbon dioxide, methane, nitrous oxides and fluorinated gases (e.g. refrigerants). Scientists used computerized models to test different factors that influence the earth’s temperature and have determined that the increasing concentration of greenhouse gases in the atmosphere is the only valid explanation for the rate of increase we are experiencing.

Warming of our landmasses, and most importantly our oceans, changes the global pattern of ocean currents that dictate the characteristics of climate and weather. This affects every organism on earth.

Montana, like other northern states, is actually warming faster than the United States as a whole and is projected to continue to do so. Depending on the effort we make to combat global warming, average temperatures in Montana are projected to increase by 5.6 to 9.8 degrees F by the end of this century. This would have significant impacts on our environment and our way of life. We will discuss those potential impacts in future articles.

The authors are members of the Kootenai Climate Group