So You Accept Global Warming but Deny the Human Component?

Many people have taken the position that the Earth is warming and/or that the climate is changing, but are “skeptical” or in outright disbelief that humans and their burning of fossil-fuels are the primary reason for this phenomenon. To some this may seem like a moderate position, but in reality, it is as extreme and ignorance-based as complete denial of warming itself. The denialist position is not a position carefully arrived at after looking through the scientific peer-reviewed data, it is a retreat. It is the position a person takes after having been dragged kicking and screaming from total denialism.

Society has itself finally accepted, at minimum, a warming in enough numbers that denialists have shifted their position to avoid looking foolish. But since they still hold the same ideological dogmas that the liberals must be wrong on this issue, they have shifted to denying humanity’s role in the warming rather than the warming itself. However, they are as wrong on this as they were when they were denying the warming.

Carbon, the greenhouse effect, and human emissions

The scientists haven’t just been predicting random warming for more than a century without any idea of a cause; a carbon dioxide-driven green house effect was the hypothesis from the beginning, and everything since then has only confirmed their hypothesis (e.g., Arrhenius, 1896; Baes, Goeller, Olson, & Rotty, 1977; Callendar, 1938; Kaplan, 1960; Keeling, 1970; Manabe & Wetharald, 1967; Peterson, 1969; Plass, 1956, 1959; Revelle & Suess, 1957; Sawyer, 1972). Titles such as The Artificial Production of Carbon Dioxide and Its Influence on Temperature by Callendar (1938) and Man-Made Carbon Dioxide and the “Greenhouse” Effect by Sawyer (1972) make this unambiguously clear.

Newer studies such as those by Berner and Kothavala (2001), Fielding, Frank, and Isbell (2008), Frakes, Francis, and Syktus (1992), Ghosh and Brand (2003), Maher and Chamberlain (2014), Marzoli et al. (2004), Reichow et al. (2009), and Royer, Berner, Montañez, Tabor, and Beerling, (2004) are just a few examples of the continuing mountain of research demonstrating the power of CO2 as a greenhouse gas, and its role in changing the Earth’s temperature.

What about the Earth’s tilt?

McDermott (2001) explains that Milankovitch cycles (the fancy name for changes in the Earth’s tilt relative to the Sun) are detectable players affecting global temperatures on scales from 1 to 100 thousand years, while its effects at time scales of 1,000 years and less are virtually too small to detect. Climate science textbooks summarize that the primary effects of the Milankovitch cycles are seen at time scales above 10,000 years and are inconsequential when studying climate at time scales less than that (Ruddiman, 2000; Wilson, Drury, & Chapman, 2005).

In other words, the Earth’s tilt can have nothing to do with the drastic increase in average global temperatures in the last 150 years. Unless the Earth’s orbit around the Sun has reversed course and done more than 10,000 years worth of travel in 150 years, it cannot be the cause of the warming. I say reversed its course because we are actually in a cooling cycle as far as the Earth’s tilt goes. That means AGW is overpowering the “natural” patterns working against it.

Even at large time scales Milankovitch cycles only trigger warming, they aren’t the cause for most of it. Wunsch (2004) estimated that changes in the Earth’s tilt only account for 20% of the overall temperature change. Most of the temperature changes result from the initial warming causing the oceans to release stored CO2, causing further warming, more CO2 to be released, and thus a cascade of feedback warming occurs.

In other words, yes, the scientists have thought about the Earth’s tilt, and based on mountains of evidence, concluded the Earth’s tilt has nothing to do with the surge of warming in the last 150 years.

What about the Little Ice Age and the Medieval Warm Period?

Crowley and Lowery (2000) explain two reasons why the Medieval Warm Period (WMP) is not helpful for the denialist argument: 1. The temperature during that time period was for the most part at cooler-than mid 19th century levels, and 2. it was a regional phenomenon, not a global change. In other words, the WMP isn’t an example of the Earth spontaneously warming quickly and independent of CO2 concentration; it was just a short-lived moderate temperature shift specific to places in Europe and the northern hemisphere.

Further supporting this, Mann et al. (2009) used numerous data series to analyze global temperature during both the WMP and the Little Ice Age (LIA), also finding that those were regional rather than global occurrences. In short, while it was hot in Europe during the WMP, it was much colder than usual elsewhere, and global average temperature was not as high as today. Similarly, the LIA meant colder temperatures in the northern hemisphere but warmer temperatures in the southern hemisphere. Mann and colleagues further concluded that El Niño events, the North Atlantic Oscillation, and the Arctic Oscillation were important factors driving climate shifts during the WMP and LIA. So the factors causing those events aren’t exactly unknown.

And before anyone tries to dismiss that last bit of evidence simply because their boogie-man, Michael E. Mann, was involved in the study, I will point out that such results have been replicated by other scientist such as Ahmed et al. (2013). Those authors concluded explicitly that “there were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age.”

To make it painfully clear, the WMP and LIA resulted NOT from from differing amounts of trapped solar energy (which is all that matters to the argument for or against AGW), but from the existing energy being shifted around largely by aberrant ocean currents, causing strange regional weather patterns like the LIA and WMP.

The Sun

The Sun is not the driver of our increase in temperature. Fröhlich & Lean (1998) determined that there was no increase in Sun irradiance during the period they looked at, 1978–1996, and that the Sun contributed little if any to the global increase in temperature. Looking at possible factors affecting global temperature such as variations in solar radiation and atmospheric aerosol concentrations, Hansen and Lacis (1990) determined CO2 to be the primary factor driving temperature increase, not the Sun. Addressing potential shortcomings of previous papers and adjusting for multiple factors Solanki and Krivova (2003) determined that “the solar influence on climate (through the channels considered here) cannot have been dominant.” Yeo, Krivova, and Solanki (2017) confirmed these findings using improved methods.

Graph from Skeptical Science: Global temperature (red, NASA GISS) and Total solar irradiance (blue, 1880 to 1978 from Solanki, 1979 to 2009 from PMOD), with 11-year running averages

Essentially, during the last 4 or 5 decades average global temperature has continued to climb while the Sun’s output has declined, deflating the position that it is the cause of our warming. Additionally, if the Sun was the reason for the warming, we should be warming from the outer layers of atmosphere inward. Instead, the outer layers of atmosphere are actually cooling while the layers closest to the surface are heating. That is a tale-tell sign that the warming is coming from within (us pumping CO2 into the atmosphere), not from the Sun.

Another thing to look at is the scale of the Sun’s irradiance. The difference in Sun irradiance between 1880 and the early 2000s is 0.4 W/m squared out of 1,365.3. That is a difference of 0.029%. When looked at with all the other evidence, that doesn’t make for a very convincing “the Sun dunnit” argument.

It is not just my interpretation of the evidence

I have thus far reviewed a considerable amount of peer-reviewed information on the science of climate change. But I am not so hubristic as to assume that that is sufficient to qualify me as an expert on climate change (though I am more of an expert than any denialists I’ve encountered). The experts spend careers studying the topic. What do they say about AGW? They say the same thing I say—or at least 89-97% of them do (Anderegg, Prall, Harold, & Schneider, 2010; Carlton, Perry-Hill, Huber, & Prokopy, 2015; Cook et al., 2013; Doran & Zimmerman, 2009; Farnsworth & Lichter, 2012; Oreskes, 2004; Stenhouse et al., 2014; Verheggen et al., 2014). Average global temperatures have been increasing, and the primary cause is the production of CO2 from fossil-fuel burning.


The talking point that goes, “of course the climate is changing, it has always changed” needs to die. Saying it is one of the quickest ways to demonstrate that you know nothing about the topic of climate change outside of memorizing partisan talking points.

The problem is not that climate changes, the problem is that the current warming was directly driven by human burning of fossil-fuels, and that the future economic and ecological costs resulting from it could have been largely avoided. The problem is that we’ve done 5,000 years worth of changing in 150 making it more difficult and costly for humans to adapt to it, and virtually impossible for many animal and plant species.

Climate change doesn’t become false because you don’t like what liberals may suggest to do if it is true. It doesn’t matter if the liberals were wanting to institute Stalinist totalitarianism, you can’t hold the facts hostage to your fears about how your political enemies will use it.

Admitting the anthropogenic cause of our increase in temperature is imperative if we want to have an evidence-based approach to public policy relating to it. Rabid partisan denial of basic facts because they are inconvenient is never a good way to move forward.


Categories Climate Change, Politics, Science

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