Do we have global warming? If measured against temperatures of a couple centuries ago, the answer appears to be “yes”. If measured against apparent temperatures of a thousand years ago, the answer would be “no”. It was back then that the Vikings colonized Greenland, only to be frozen out some centuries later when the temperatures fell and farming along with raising cattle for meat and milk became impossible. With the lower temperatures, the Thames froze over to the point that various festivals could be held on the ice. The canals in Holland froze over allowing ice skating to become commonplace. During the American Revolution, cannon were dragged across the Hudson River, which indicates that winters were colder then than they are now. It appears from this that variations in the Earth’s temperature can vary quite a bit. As the people of a thousand years ago were “pre-industrial”, we can safely assume that they did not release sufficient CO2 to alter the climate of the time. Nor do we really know why the Earth was colder a couple centuries ago than it was a century or so later. While volcano eruptions can alter climate, the biggest eruption in 1815 of Tambora only effected climate for a few years. The supposed Yellowstone “supervolcano” would likely affect our climate a lot more, but there were no known supervolcano eruptions in the last thousand years. So what did cause the world to cool down? The only answer that seems to make sense is that the Sun’s output varies from time to time. We know that the solar is a part of an arm of our galaxy. We also know that there are great clouds of “dust” scattered here and there through our galaxy. There are measurable changes in solar output that appear to be related to the number of “sunspots” on the solar disk as seen from the Earth. Whether or not the Sun undergoes longer term changes is unknown at the present time. We do know however that in the last million or so years, the Earth has several times been covered by great glaciers which came below 40 degrees of latitude down from the polar regions. There were “warm” periods between these “cold” periods, the last one before ours had temperatures apparently 4C. higher than what we now experience. These series of changes in our climate did happen. However we do not know exactly “why” they happened, only that they did. It should also be noted that for millions of years before this, there was far less change in our climate. If you go back far enough, there is evidence that at one time the Earth was far colder, times where it was much hotter. At one time the oxygen level of the atmosphere was higher than it is now, which resulted in gigantic insects (compared to those of today). Supposedly at one time due to volcanic activity, the CO2 level reached according to one estimate 2000 parts per million.* We are around 400 parts per million today. Prior to the industrial revolution and the burning of fossil fuels, we were somewhere around 280 parts per million CO2.
*Peter Douglas Ward states this in his study of the mass extinction at the end of the Permian era. His books are well worth a visit to your public library.
Our use of fossil fuels has increased the amount of CO2 in the atmosphere by 120 parts per million over pre-industrial levels. Or about 43%. Note however that this is not a constant over the entire Earth. Areas with more vegetation will generally have lower CO2 readings since plants use CO2 and strip off the carbon atom for their own use. However we are reducing the amount of vegetation over the world compared to what existed before. Plus cities tend to “trap heat” and are hotter than rural areas because of this. Then the use of air conditioning means that generating cold air also raises outside temperatures as the energy consumed by the air conditioners has to go somewhere. The effect of atmospheric water vapor has not had the attention it should have as it in effect a stronger “heat trap” than CO2 is. And of course everyone knows that damp hot air is a lot more uncomfortable than dry hot air is. This should also be a consideration. One problem is that we have large “inefficiencies” in the generation of useful energy. There is a lot of “waste heat” generated by fossil fuel engines which has to be disposed of somehow. Electric motors are more efficient, but they aren’t perfect either. Transmitting electricity results in loses depending upon the distance the electricity has to travel to reach the final user. It also takes more electricity to charge a battery than the electricity you can extract from that battery. And rechargeable batteries eventually have to be replaced with new ones.* In any case, the electricity to charge batteries and run motors has to come from “somewhere”.
* A Japanese company is developing a “carbon” rechargeable battery with better life plus being able to be recharged faster than present lithium ion batteries. Assuming this invention does pan out, the outlook for electric cars for urban transport improves considerably. And with fast recharging, even rural travel becomes “practical”. It should be noted here that fossil fuels are not all the same. Natural gas is the “cleanest” of the fossil fuels, alcohol is next, then gasoline, with coal being the worst CO2 producer. However reducing US CO2 production by importing more from China and India does not help matters as we’re merely moving the CO2 production from one place to another… And while wind and solar can help reduce our dependence upon fossil fuels, we still need an additional source of reliable energy that is “safe” to use. This would be “geothermal” energy, which taps the Earth’s natural heat underground and puts it to use. It would appear to me that the practice of “fracking” might have applications for geothermal energy. In any case, it is worth looking into here. And to answer the question that I used as the title, yes, it is my belief it is warmer now than it was back in 1938 when I was born here in Muskegon, Michigan. How much? I’m not really sure, but it is my impression that our average temperatures over the years are slightly higher than they were in the past if you now average out the yearly temperatures. The difference isn’t very great, but over the 75 years I’ve been alive, I do think it is a bit warmer now than it used to be. Not by a whole lot, as the population when I was born was less than half of the population we have now, but it does seem “warmer” to me. Last winter wasn’t, but it was a colder and longer winter than most of those we’ve had in the last couple of decades. Going back however further, we’ve had a couple of winters just as bad back in the late “70’s and early 80’s.