Personal Note: Dr. Gray was in the process of writing up the results discussed below when he passed away in 2016. Before he died, he asked us to compile his figures and preliminary text into a paper to be posted online. We have attempted to maintain his writing style and the tone that we think he would have wanted to convey. Dr. Gray studied tropical meteorology for over 50 years (Klotzbach et al. 2017, available below), and we believe that his views on this important topic should be heard. Please note that the views of this paper are Dr. Gray’s and may not be our own personal views on climate change. Barry Schwartz, Phil Klotzbach and Sarah Gray
Flaws in Applying Greenhouse Warming to Climate Variability
By Bill Gray (Professor Emeritus, Department of Atmospheric Science, Colorado State University)
Edited by: Barry Schwartz (retired from NOAA), Phil Klotzbach (CSU) and Sarah Gray (Univ. of San Diego)
There is little controversy that the earth has experienced a warming trend since the mid 19th century with an acceleration of this warming from the mid-1970s to ~2000. Following a hiatus in global warming for about 15 years, the globe began warming again around 2014, associated with the El Niño that developed around that time. What is in dispute is whether these periods of warming are the result of changes to the earth’s energy balance due to a) human addition of greenhouse gases to the atmosphere, b) natural variability of the climate system, or c) a combination of both factors.
The idea that the earth’s climate can be altered by addition of greenhouse gases is known as the greenhouse theory and is depicted in Fig. 1. Of most concern is the addition of carbon dioxide (CO2 ) to the earth’s atmosphere as a result of the burning of fossil fuels and deforestation. This theory has been the subject of debate since its introduction by Joseph Fourier in 1824.
Fig 1. The Greenhouse theory of global warming (after Trenberth 2009).
Climate sensitivity is complex and involves much more than the state of radiation balance and greenhouse gases. The globe’s climate system is in a close state of energy balance. A global radiative average imbalance of 1 Wm-2 (or 0.3%) of the difference between the continuous solar radiation impinging on the earth and infrared energy being fluxed to space can bring about significant climate changes if this small energy imbalance were to persist over a period from a few months to a year or two. The critical argument that is made by many in the Global Climate Modeling (GCM) community is that an increase in CO2 warming leads to an increase in atmospheric water vapor resulting in more warming from the absorption of outgoing infrared radiation (IR) by the water vapor. Water vapor is the most potent greenhouse gas present in the atmosphere in large quantities. Its variability (i.e., global cloudiness) is not handled adequately in GCMs in my view. In contrast to the positive feedback between CO2 and water vapor predicted by the GCM’s, it is my hypothesis that there is a negative feedback between CO2 warming and and water vapor. CO2 warming ultimately results in less water vapor (not more) in the upper troposphere. The GCMs therefore predict unrealistic warming of global temperature. I hypothesize that the earth’s energy balance is regulated by precipitation (primarily via deep cumulonimbus (Cb) convection) and that this precipitation counteracts warming due to CO2.
1. CO2 observations and exaggerated global warming predictions
Continuous measurements of atmospheric CO2 which were first made at Mauna Loa, Hawaii in 1958 show that atmospheric concentrations of CO2 have risen since that time.
The warming influence of CO2 increases with the natural logarithm (ln) of the atmosphere’s CO2 concentration. With CO2 concentrations now exceeding 400 parts per
million by volume (ppm), the earth’s atmosphere is slightly more than halfway to containing double the amount of CO2 from the 280 ppm CO2 amounts in 1860 (at the beginning of the Industrial Revolution) [(ln 400/280) = 0.357 in 2016 versus (ln 560/280 = 0.691) when CO2 doubles near the end of this century].
Given this increase in CO2, we have not observed the global climate change we would have expected to take place. Assuming that there has been at least an average of 1 Wm-2 CO2 blockage of IR energy to space over the last 50 years and that this energy imbalance has been allowed to independently accumulate and cause climate change over this period with no compensating response, it would have had the potential to bring about changes in any one of the following global conditions.
- Warm the atmosphere by 180°C if all CO2 energy gain was utilized for this purpose – actual warming over this period has been about 0.5°C, or many hundreds of times less.
- Warm the top 100 meters of the globe’s oceans over 5°C – actual warming over this period has been about 0.5°C, or 10 or more times less.
- Melt an average amount of land-based snow and ice so as to raise the global sea-level by about 6.4 meters. The actual rise has been about 8-9 cm, or 60-70 times less. The gradual rise of sea-level height has been only slightly greater over the last ~50 years (1965-2015) than it has been over the previous two ~50-year periods of 1915-1965 and 865-1915 when atmospheric CO2 gain was much less (Church et al. 2008)
- Increase global rainfall over the past ~50-year period by 60 cm.
- Large and important counterbalancing influences to CO2’s energy addition must have occured over the last 50 years to negate most of CO2’s expected climate change if CO2 gain were the only influence on climate variability. Similarly, this hypothesized
- CO2-induced energy gain of 1 Wm-2 over 50 years must have stimulated a compensating response which acted to largely negate energy gains from the increase in CO2.
Read the entire paper, which is well worth your time, but too long to present here in entirety. PDF, open access – here: https://wattsupwiththat.files.wordpress.com/2018/01/bill-gray-climate-change-1.pdf
Additionally, there was a recent tribute paper in the Bulletin of the American Meteorological Society, that covered decades of Dr. Gray’s work. Also open access:
Thanks to Dr. Philip Kloztbach for selecting WUWT to publish this.