First off, the long term trend presented here starts around 1890. So that trend results, to a degree we cannot determine, from the natural warming following the end of the Little Ice Age. But there were temperature trends before that, we just don’t have direct thermometer measurements to consider. Nevertheless, we can confidently say some things about those trends. Such as, there was a long term cooling trend from the Medieval Age to the Little Ice Age. And there were warm periods during Roman times and before that when the Egyptian Empire was young.
Second, we must be careful to observe the time period when charts are presented to us. Example: Ethan’s chart about how “skeptics” view global warming starts at 1970. That was around the end of thirty years of cooling so pronounced that the worry was that the world was slipping into a new ice age. Warming would be expected. But present the same data on a longer time scale, say from 1950 when we started getting reliable atmospheric data from balloon measurements, and we see a decline from 1950 to the mid 1970s, and then a recovery to the present day. Atmospheric temperatures are now about what they were in 1950.
Ethan says “…that it continues to rise — is a real long-term problem facing the entire world”. Well, it continues to rise in the limited time scale Ethan presents us, but on longer time scales it rises and falls throughout human history; no one knows what trend this century will follow because climate is heavily affected by many powerful natural forces.
Third, Ethan says of the long term (meaning since the end of the Little Ice Age) warming trend “…that’s also the component that humans — through emissions reduction, energy efficiency, renewable power, policy changes and (possibly) geoengineering — can do something about.” Those actions all consist of stopping things that humans are doing: burning fossil fuels. Stopping certain human actions will only “do something about” global temperatures if doing those things is what is causing those changes in global temperatures. If it isn’t, stopping them will have no effect. That causality is not scientifically proven; it is still an assertion hotly contested.
What the Manmade Global Warming “proof” consists of is the warming trend since the Little Ice Age concurrent with the increased CO2 of the Industrial Age. In other words, a correlation. Correlation is not causation. Causation requires proof that is yet to be developed.
The assertion that current warming trends are beyond what natural forces could produce, requiring the added force of human activity, is a theory that is hotly contested and not at all scientifically proven. On a geologic time scale, there is little correlation between temperatures and atmospheric CO2, and many instances of natural warming and cooling trends much stronger than what we see today. It is quite possible that humans could succeed in twisting our economies into knots with expensive, unreliable and difficult energy sources, and then have no effect on global temperature trends. Science’s understanding of the climate is far too crude to sort that out.
Fourth, as readers we have to be sensitive to and aware of the tricks and codes words writers use to advocate their side and denigrate the other side. We are all familiar with the word “denier” used in this way, linking skeptics to Holocaust Deniers. Ethan uses words like “insidious argument”, “usual suspects”, “anti-science claims” and “dishonest arguments” to describe the other side. Even the word “skeptic”; would Ethan describe astronomers who aren’t convinced that a new theory has been scientifically proven as “skeptics”? Or is a new theory considered correct until it has been disproven?
He says that warming won’t stop until there is a causative reason, “and there isn’t one”; sliding the reader quickly past the fact that climate is governed by multiple, powerful, and natural forces any of which could suffice as a “causative reason” to change climate, and hoping the reader agrees without thinking about it that only human action can provide that “cause” — the conclusion Ethan wants us to arrive at.
I highly doubt Ethan would ever use such tricks when discussing the astronomical work of a fellow astrophysicist.
Fifth, Ethan starts the article by quoting Richard Muller “…as a scientist I was trained you always have to show the negative data, the data that disagrees with you”. The advocates of Manmade Global Warming never deal with negative data, never acknowledge its existence, never debate it; in the face of such data, the response is always the same — that scientist’s work is funded by oil companies, that person is a know denier, 97% of scientists agree with us so why listen to the deniers. Astrophysicists not only don’t react that way to challenges to their data or conclusions, they themselves actively try to disprove their own work before publishing it. That is the polar opposite of how Global Warming Scientists have behaved.
The charge that an astronomer would “adjust” his data to make his conclusions more pronounced would be a career ender. But since 1999, that has been routinely done to the NOAA/NASA temperature records. That the records have been repeatedly altered is beyond dispute. The justifications have not been openly discussed or defended. The fact that all of the changes have magnified the alleged warming trend can’t be mere coincidence.
Then there is the fact that radiosonde balloon data and satellite measurements do not confirm the strong warming trend of the “adjusted” data, a fact which has not been explained. Wouldn’t Richard Muller, and shouldn’t Ethan, as good scientists, demand that the contrary, negative data be shown and thoroughly debated? The assertion that “the debate is over” is absurd; the scientific debate has truly not begun.