My tenth grade history teacher, good old Mr. Hennis, used to paraphrase the philosopher George Santayana: "Those who do not remember 10th grade History are condemned to repeat it." Well, a number of people seem to have trouble remembering history when it pertains to climate change.
First, the Earth was in an Ice Age some 10,000 years ago, and for some imperfectly understood reasons, that Ice Age came to an end, and the globe warmed abruptly. Our current warming period is believed to be long lived but ultimately it is expected to end, , and we expect to go back to an Ice Age someday (but probably not this year despite our lousy weather, which is due to La Nina plus the North Atlantic Anomaly and the Polar Oscillation all going haywire at the same time).
In addition, more recently there was a Medieval Warming Period from 950 to 1250, which coincided with the rise of the Vikings, and the colonization of Greenland, which really was green at the time.
There was also a Little Ice Age, from circa 1650 to 1850, during which time the Thames River in England froze in the wintertime, and in addition Charles X of Sweden marched an army from Sweden to Estonia in 1658, over a frozen Baltic.
We had a Year Without a Summer in 1816.
In the 1920's, through the 1930's significant glacier melt was recorded in Greenland. The amount of melting is estimated to be 50% higher than similar melting that occurred in the 1990's and 2000's, according to Petr Chylek's group at Los Alamos National Lab.
There was also a major disruption in climate observed in the 1930's in which the Western US was besieged by the Dust Bowl. Some ecologists believe that it is a historical fact that poor soil management was the sole cause of the Dust Bowl, although others wonder if it might be part of a larger pattern.
After a long warming trend, from 1940 to 1975 there were colder temperatures in the Northern Hemisphere (i.e., a least squares plot of global average temperature as estimated by the National Climatic Data Center shows a gradual cooling trend).
Then from 1976 to 2002, global average temperature rose by about 0.5 degrees Celsius.
From 2002 to 2010, however, the global temperature has been about constant, as estimated by the NCDC. Some of my passionate friends have had trouble believing that global average temperature has not risen since 2002, but, as Casey Stengle used, you say, you can look it up:Many skeptics have expressed doubt concerning the observed global warming that occurred from 1975 to 2002. However, the Village Elliot believes that the data, though a bit fuzzy, is clear enough that there can be no mistake. The earth did get warmer, at least until 2002, and it's silly to argue otherwise.
Left to be determined is how much of that warming is due to natural cycles such as the North Atlantic Oscillation and the Arctic Oscillation, versus anthropogenic causes and specifically carbon dioxide. The Village Elliot believes that other human-caused environmental issues such as ocean pollution may also play a major role.
What should be done about this? That also is up for grabs. Currently most of the Western nations urge a general dismantling of the fossil fuel economy, with the brave hope that something else will soon pop up to replace it. So far, however, an inexpensive substitute for fossil fuels has not be identified, at least not anything that can replace the billions of tons which we now use.
However, climate change is not a simple subject, and if we hearken back to a time in history when climate was totally predictable, well, that probably is a fantasy.
The Village Elliot also despairs of the ability of the scientific community to have reasonable discussions on this subject. In recent years, it seems that it has become acceptable to present a slanted, unbalanced view of the information in order to win an argument rather than to emerge with the best science. It's more about what is persuasive, rather than what we actually believe to be true.