It is certainly not news that it has been incredibly warm this past winter over most of the country. Here in the Colorado High Country, the warm sun has already melted the tiny amount of snow we managed to get this winter. Even A-Basin, the closest thing we have to the Alps, had to close its Montezuma lift in March. Back in Wisconsin, the Geneva Lake tour boats were operating in March for the first time ever.
One is tempted to blame this unseasonable weather on our changing climate, but it's not that easy. Climate, it turns out, is long term, average weather and weather pattern changes in one direction or the other since last year have no bearing on the long-term direction our climate is heading. On the other hand, continuous, year-after-year observations of higher average daily low temperatures are signals the climate is getting warmer. The same story goes for average moisture. If we continue to receive less moisture year after year, the climate charts will gradually change.
There is no longer any real argument. The average temperature of the Earth's surface and water temperatures have been rising, and the rise is most evident in the northern hemisphere. This is most dramatic over the last decade where we have seen many "first time ever" events relating to our warming climate. At a Summit Foundation presentation at CMC last month, David Thoreson presented dramatic pictures of a sailing expedition through the Northwest Passage; a feat that would have been far more difficult a decade ago. For those who insist on checking it out for themselves, you can now book tours - and the boats do not need icebreaker support.
Those who tend to blame the sun for this trend now have a problem. The sun's peak irradiance has been decreasing since the early '90s. At the same time, our average global temperatures have remained stable or even increased during low or declining periods in our solar cycles. Since the late '70s, the trend is going steadily upwards, and contrary to what some politicians may think, the sun is not the main contributor. I am personally convinced it has to do with our growing use of carbon fuels, and there is sound scientific evidence to prove it. Unfortunately, we have a large percentage of our elected officials who still think anthropologic (human-caused) global warming is a hoax.
Our routine weather patterns have more to do with the various air pressure and temperature oscillations over our oceans and the periodic "El Nino" and "La Nina" events that have been measured for decades. The trigger for many of these events is the surface temperature of the water in our oceans, including the Arctic Ocean. Changes in polar temperatures can cause jet streams to move further north or south as well as impact their intensity. These jet streams drive the weather fronts that continuously impact our North American continent. Changes in these jet streams control how warm it gets and how much moisture hits a particular area. When the Gulf of Mexico is warming up while strong cold fronts are blowing in over the Rockies, huge colliding air masses can result in major storms, some of which can cause major tornadoes. With a warming of our oceans, and more importantly, with the opening of large areas of ice in the Arctic, there is potentially a risk of dramatic cooling of the waters in the northern oceans. As the temperature differential between the northern Pacific and the Gulf increases, stronger storms may result.
Given that our climate is getting warmer, it is certain we will see changes from what is regarded as the norm. Warmer air will also cause the water vapor content in our atmosphere to increase, adding further stimulus to this warming effect. Water vapor is also a "greenhouse gas," just like carbon dioxide, and clearly has an impact on the direction our temperature trend is going. As it gets warmer and the polar ice melts, there is less reflection of the suns rays and even more heat is radiated from the earths surface; adding even more outbound infrared energy to the equation. We are starting to see this energy balance shift in a direction where we better start compensating for the changes that we will see in the future. That is a message some of our political candidates do not want to hear.
Dave Yost is a retired Bell Labs engineer, now living in Williams Bay, Wisc. and Silverthorne. He can be contacted at firstname.lastname@example.org.