By Andy May
Some have speculated that the distribution of relative humidity would remain roughly constant as climate changes (Allen and Ingram 2002). Specific humidity can be thought of as “absolute” humidity or the total amount of water vapor in the atmosphere. We will call this amount “TPW” or total precipitable water with units of kg/m2. As temperatures rise, the Clausius-Clapeyron relationship states that the equilibrium vapor pressure above the oceans should increase and thus, if relative humidity stays the same, the total water vapor or specific humidity will increase. The precise relationship between specific humidity and temperature in the real world is unknown but is estimated to be between 0.6 to 18% (10-90%ile range) per degree Celsius from global climate model results (Allen and Ingram 2002).
Carl Mears and colleagues (Mears, et al. 2018) have recently published a satellite microwave brightness record of TPW from 1988 to 2017 showing TPW, over the world’s ice-free oceans, increasing in lockstep with global mean temperature. This surprised me since Benestad (Benestad 2016), (Partridge, Arking and Pook 2009), (Miskolczi 2014) and (Miskolczi 2010) have previously reported that TPW, as computed from weather balloon data, has gone down recently, although their time periods were earlier and longer than the record shown in Mears, et al. Continue reading
Opinion by Andy May
Al Gore wrote in the Huffington Post (August 28, 2014) that the need for “bold action” to curtail “old dirty sources of energy … is obvious and urgent.” The proper scientific response to an assertion like that is why? How can I test this idea? Science is not a belief, it is a method of testing ideas. We use an idea to make predictions and then we gather data to see if the predictions are correct. If the predictions are accurate, the idea survives. If any of the predictions fail, the idea is disproven, and it must be modified or simply rejected. Continue reading
By Andy May
U.S. coal production declined from 2011 through 2016 as it was displaced in U.S. power plants by cheaper and cleaner natural gas. Some of the reduction was also due to the Obama Clean Power Plan regulations. However, the shale gas revolution in the U.S. has not spread to other countries, perhaps due to the “fracking” scare, so worldwide use of coal increased rapidly until 2013. From 2000 until 2013 global coal use increased at a rate of over 4% per year. This led to an increase in U.S. coal exports (see Figure 1) because the U.S. is a low-cost producer of high quality coal. Coal consumption worldwide has flattened and is expected to stay flat through 2040, according to ExxonMobil’s 2018 Energy Outlook as well as the EIA. Currently coal provides 25% of the global energy supply and this is projected to decrease to 20% by 2040 according to ExxonMobil. Continue reading
By Andy May
While researching fossil fuel history recently, I discovered a PBS article entitled “The Whale Oil Myth.” You can see the full article here. It is based on another blog post on the environmental history web site here. The authors are not identified, but the original ideas are from Dr. Bill Kovarik from the School of Communication at Radford University and the late Dr. Lester Lave, an economist at Carnegie Mellon University. Continue reading
By Andy May
18O is a rare isotope of oxygen. The ratio of 18O to the normal 16O in foraminifera fossils (“forams”) can be used to estimate paleo-ocean temperatures. Higher values mean lower temperatures. A recent article on geologypage.com (here) led me to Bernard, et al., 2017, which has experimental data that suggest 18O concentrations can be altered in fossils by solid-state diffusion after fossilization. This can corrupt the measurement and the resulting calculated temperature. According to Bernard and colleagues, the 18O concentration alteration is visually imperceptible, so one cannot tell the fossil has been altered by visual inspection. If their results are valid, how will this impact our view of climate history? Continue reading
By Andy May, Michael Connolly and Ronan Connolly
In this post, we will discuss the tropopause, atmospheric molar density and the lapse rate (the change in atmospheric temperature with altitude). The key points are:
- A change in the molar density versus pressure best-fit line is a change in the equation-of-state.
- The NOAA and WMO definitions of the tropopause are different and somewhat clumsy.
Molar density plots are a better and more robust way to pick the tropopause.
By Andy May
Georgiou, et al. 2015 have reported that coral reefs in the Australian Great Barrier Reef, near Heron Island, are insensitive to ocean pH changes. Continue reading