Some of the net Global Warming since 1880 is undoubtedly due to human actions, but how much?
[Update 10 April. My PowerPoint Show that includes the following graphic is available for download here: https://sites.google.com/site/iraclass/my-forms/2014%20Global%20Warming%20Civil%20Discourse.ppsx?attredirects=0&d=1 ]
The height of the bars on the graphic indicates the relative magnitude of Natural Processes and Cycles (in BLUE) versus Human-Caused Warming (in RED). The scale on the left is in °C with corresponding °F on the right.
Going from left to right:
The first BLUE bar represents the Atmospheric “Greenhouse” Effect, responsible for about 59°F (33°C) warming. This is the Natural Process that makes life as we know it possible on Earth. The mean temperature on the surface of the Earth is about 59°F (33°C) warmer due to Atmospheric absorption of long-wave radiation by water vapor (H2O), carbon dioxide (CO2), and other so-called “Greenhouse” gases, and the subsequent “back-radiation” of some of this heat energy towards the Earth surface. (See my WUWT Visualizing series [Physical Analogy, Atmospheric Windows, Emission Spectra, and Molecules/Photons
Light and Heat])
The second bar represents the major Natural “Ice Age” Cycles that have occurred about every 100,000 years according to the ice core records from the past 400,000 years. The climate is always changing, with up and down temperature jigs and jags at all time scales. The major Ice Age Cycles change temperatures over a range of about 13°F (7°C ).
The third bar represents the Human-Caused Warming that my wife and I experienced when we retired from full-time employment and moved from Upstate New York to Central Florida. The average temperature in Florida is about 20°F (11°C ) warmer than that in New York. I miss cross-country skiing a bit, but, overall, we are happy here and we enjoy water aerobics. While not exactly “Global” Warming, this warming was certainly caused by our Human-Caused decision to move and, of course, we enjoy the resulting moderately higher temperatures :^).
The fourth and fifth bars represent the YEARLY 43°F (24°C ) temperature range (July mean minus January mean), and the DAILY 19°F (11°C ) temperature range we experience here in Central Florida. Please notice that these ranges are much larger than the Ice Age Cycles, and they recur on a daily or yearly basis.
The sixth bar represents the mean Global Warming since 1880 based on the official NASA GISS accounting. It is 1.4°F (0.8°C). According to the IPCC, the majority of this Global Warming is due to human activities (mainly unprecedented burning of fossil fuels and land use that has reduced the albedo of the Earth). I have interpreted “majority” to mean about 70% and have therefore allocated 1°F (0.6°C) to Human-Causation and the remaining 0.4°F (0.2°C) to Natural Cycles.
The seventh bar represents my personal opinion as to the actual Global Warming since 1880, discounting the “adjustments” made by the official Climate “Team” that I believe have inflated the temperature record. We know that the US thermometer record is so unreliable that it has had to be “adjusted” several times by the official US Climate “Team” at GISS, see The Past is Not What it Used to Be, and Skeptic Strategy.
The above GISS email from Makiko Sato to James Hansen details seven adjustments to the US thermometer record, made from 1999 to 2007. According to GISS, the very warm year 1998 was originally thought to be 0.541°C (0.97°F) COOLER than 1934, which, in a warming world, would be, let us say Inconvenient. It took multiple “adjustments” to bring them to a dead heat. Further adjustments to the thermometer records subsequent to the 2007 Sato email have brought 1998 up to a significant lead over 1934 :^).
When this email came to light due to a Freedom of Information request, it was explained away by Warmists as follows:
1) The adjustments correct for differing Times of OBServation (TOBS). OK, that could be true, but why did it take so many analyses to come to the correct result? It seems one or two would be sufficient. Also, the 1998 data has been warmed more by the TOBS adjustments than the 1934 data has been cooled. Are we to believe that TOBS was less standardized in 1998 than it was in 1934?
2) The US is only 2% of the Globe. Therefore, any adjustment to US data would have only a minor effect of Global data. True enough, but, if US data is so unreliable that it has had to be adjusted so much, are we to believe that world data is any better? Does anyone really think that years-old data from Asia, Africa, South America is more reliable than US data? That ocean data based on some seaman dropping a bucket overboard, hauling it back, and sticking a thermometer into it, is any better than US thermometer data?
So, unless we believe that the world temperature record is more reliable than the US record, it is likely the world record has also been similarly “adjusted”. Therefore, I have discounted the GISS estimate of Global Warming by about 30%, so actual warming is about 1.0°F (0.6°C). As for allocation of this actual warming to Human- vs Natural-Causes, I believe the IPCC has over-estimated Climate Sensitivity by a factor of two or three, so I have allocated the majority of the warming 0.8°F (0.5°C) to Natural Cycles, and the remaining 0.2°F (0.1°C) to Human-Causation.
I’d appreciate comments on my estimates and conclusions. advTHANKSance