There is a cooling; there is a heating.
What an elegantly simple way of describing – not climate. Perhaps the seasons. Temperatures generally rise in spring and summer and decline in fall and winter. But these seasonal changes are not climate. If one is to talk about climate, one should use the word correctly. By definition, “climate” is a description of long-term trends in weather. Trends that are at least ten years long, often more. Climate is not an instantaneous measure of temperature, but includes a long-term average.
By those rules, there has been a recent heating of Earth. Every year for the past 17, the average global temperature has been at least 0.4° C warmer than the average during the 20th century. That’s clearly “a heating.” By those rules, the average global temperature on Earth has increased by about 0.8°C since 1880. On the other hand, there hasn’t been a cooler-than-average year since 1976. It would be more correct to say, “Forty-one years ago, there was a cooling; since then, there has only been a heating.”
Eight-tenths of a degree C? That’s just a shade less than one-and-a-half degrees F. Difficult, but not impossible to detect with a tongue or a fingertip. On the other hand, that is an average of temperature readings taken from around the world. In some places, the local average increase has been higher than 0.8°C. In some places, the local average increase has been lower. (Ref 1)
Earth is warmed by the sun, by radioactive decay from deep within Earth, and by heat left over from the primordial Earth (the Hadean Eon, from about 4.5-to-4.0 billion years ago). What is important about the last two is that they are slowly but inexorably decreasing. (Ref 2) The only source of an increase in Earth’s average temperature is the sun.
The sun’s output is known to fluctuate. For example, there is an eleven-year cycle in the number of sunspots.
When there are more sunspots, the sun radiates more light than when there are fewer. In addition, when there are fewer sunspots, there is a lighter solar wind. More cosmic rays strike Earth’s atmosphere and may create aerosol particles that may create more clouds which reflect more sunlight. (Ref 5)
Recent research (Refs 3, 4) offers other measures of solar activity, and suggests an increase in some measures during the early 20th century. The effect on climate, if any, is not yet known; however, solar activity has leveled off in the past several decades, while average temperatures on Earth have continued to rise.
The amount of energy from the sun that is absorbed by Earth depends, first, on a number of cyclical factors, including the eccentricity of orbit (how close to the sun the earth is) and some wobbling of Earth’s axis, as well as the imbalance in land area in the northern and southern hemispheres. These factors were first captured by Milutin Milancović in the 1920s. Please see Ref 6 to begin a look at this.
We should be able to agree, at this point, that Earth’s internal heat is not causing a rise in average global temperatures, but that the sun’s affect on Earth’s average global temperature is the culprit (if culprit is the right word).
There is not, however, enough of a difference in solar energy explained by either the Milancović cycles or sunspot cycles to account for the recent (since 1880) increase in average global temperatures. A simple reason is that these things are, after all, cyclical and we would expect they would “level out” over the past nearly 140 years.
If you will accept what has been presented so far, perhaps you would also be willing to accept the notion that the rise in average global temperature can be laid at the feet of greenhouse gasses.
In preparation for writing the fourth book in the “Stuff of Life” tetralogy, I’ve been reading Jared Diamond’s “Collapse: How Societies Choose to Fail or Succeed.” So far, I’ve read about Easter Island, Montana (at least the Bitterroot Valley), the Maya, Pitcairn Island, and the Anasazi. What I’ve taken from this is that those collapses are largely due to bad decisions made by people in power, usually decisions made to benefit those in power at the expense of the public. Certainly there were other factors, including (let me whisper these, lest I offend) climate change and people’s inability to restrict breeding (think Malthusian catastrophe).
An order from Amazon was scanned as being at the PTC Post Office at 4 AM yesterday morning and then scanned as Out for Delivery about 11 AM. Now the order is marked as "Carrier Delay" and neither Amazon nor I can find anything else.
A package for which I paid much money for Two Day Air, and which was marked Out For Delivery by UPS on Wednesday, then marked delayed until Thursday, then marked delayed until Friday, then marked for delivery by 4:30 PM Friday was finally delivered at 5:50 PM on Friday.
Peachtree City offices and I suspect most of the schools were closed for several days. All this due to perhaps an inch of snow.
Oh, yes, and the entire government was "shut down" because either (1) some people got the guts to stand up to a bellwether that is leading us to disaster, or (2) some sort of pecker contest among idiots on both sides of the aisle, or (3) the entire Congress overdosed on Imodium and is so tight and full of feces they can't do anything, or (4) lack of interest. Perhaps, all of the above.
How are these things related? I hypothesize that they are all symptoms of the civilization we have crafted being too fragile to be sustained and well into its inevitable decline.
For a long time, I thought it was Thomas Jefferson who said that the new Republic would exist only until the people discovered they could vote themselves largess from the public purse. Apparently, there is some debate about who said that. (For example, see the reference, below.)
Still, I cannot help but watch as the current administration and its allies vote themselves and their supporters largess in the form of tax breaks for multi-millionaires while pretending to offer crumbs to the middle class while also killing off the poor and people of color by restricting or denying reasonable medical treatment. I cannot help but be aghast at the lack of honesty and ethical behavior by the administration and the coterie of vultures with which it has surrounded itself.
(Final message to supporters of the current administration, only: Are you offended, yet? Good. Maybe, just maybe, that will cause you to think for a change.)
Registered Curmudgeon, scientist, skeptic, humanist, and writer.