By Bob Valen 

The last glacial maximum

Weather Watcher

 

Last updated 9/9/2020 at 8:25am



If you live in the Coulee, it’s likely you have an inkling of glacial history and the power that can be unleashed by glaciers. The Grand Coulee is prime evidence of glacial activity. There have been about a half dozen major Ice Ages in the history of Earth over the past three billion years. The landscape we live on was, in part, created by glacial activity, cataclysmic flooding and thousands of years of lava flows. Drive the Coulee Corridor and read the new roadside exhibits, or read about the events that occurred here on the Ice Age Floods Institute website.

With the image of major glacial periods in our heads, consider what the atmospheric temperatures were like. Cold, certainly – how cold? A team of researchers from the University of Arizona have conducted work that had narrowed down the temperature of the last ice age, what is called the Last Glacial Maximum (LGM) of 20,000 years ago to 46 degrees Fahrenheit, or so. In your own experiences, 46˚F doesn’t sound ground shattering at all. So, what’s the big deal?


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Here’s what Jessica Tierney, the lead author of the research that was recently published in the Journal Nature, says. “In North America and Europe, the most northern parts were covered in ice and were extremely cold. Even here in Arizona, there was big cooling,” Tierney said. “But the biggest cooling was in high latitudes, such as the Arctic, where it was about 14 C (25 F) colder than today.” Tierney goes on to explain how climate models address high latitudes. “Climate models predict that the high latitudes will get warmer faster than low latitudes,” Tierney said. “When you look at future projections, it gets really warm over the Arctic. That’s referred to as polar amplification. Similarly, during the LGM, we find the reverse pattern. Higher latitudes are just more sensitive to climate change and will remain so going forward.”

The research team addressed Atmospheric Carbon Dioxide (C02). Our atmosphere is sensitive to C02. During the ice age, C02 levels were in the range of 180 parts per million (ppm). As humanity grew more industrialized, C02 levels began to rise. Today, our atmospheric levels of C02 are about 415 ppm. “Tierney and her team determined that for every doubling of atmospheric carbon, global temperature should increase by 3.4 C (6.1 F), which is in the middle of the range predicted by the latest generation of climate models (1.8 to 5.6 C).” The researchers plan to use the same technique to recreate warm periods of Earth’s past.

Our summer months are now history. With that, let’s take a look at what the Climate Prediction Center (CPC) says about the next three months. For September through November 2020, the CPC shows above normal temperatures and above normal precipitation, as well.

Here are the numbers for the month of August. All data are from my home weather station. The high temperature was 103.6˚F on the 16th, while the all-time high was 110.0˚F in 1961. The low temperature was 49.4˚F on the 13th, and the all-time low was 38.0˚F back in 1951. The mean for the month was 75.0˚F. The all-time mean for August is 72.0˚F. We did see a bit of precipitation. I measured a total of 0.04 inches. It fell around the 6th and 7th of August. The all-time mean precipitation for the month is 0.41 inches. The wettest August was back in 2014 with 1.76 inches.

Clear nights mean sky observations. Here’s what our friends at EarthSky.com say about visible planets. “Mercury, Jupiter and Saturn are in the sky at dusk throughout September 2020, with Mercury hard to view from northerly latitudes. Bright Mars rises in the east in the early evening. Brilliant Venus rides high in the east in the hours before sunrise.”

 

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