Some of the net Global Warming since 1880 is undoubtedly due to human actions, but how much?
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.
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