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RocketDoc Blog - Week of February 21, 2021

Global Warming – The Plan

I haven’t taken a shot at Global Warming lately so I thought I would present my plan to see what you think. I think everyone agrees the parts per million (ppm) of CO2 in the Earth’s atmosphere is increasing even we don’t all agree on how fast that is going to raise the Earth’s temperature, or even where. Figure 1 below shows the monthly mean CO2 concentration measured at Mauna Loa Observatory and the year over year trend is undeniable.

Figure 1 – Monthly Mean CO2 Concentration at Mauna Loa Observatory

Is a measurement at Mauna Loa a fair assessment of the World’s CO2 concentration? For that we fall back on satellite measurements as shown in figure 2 below. The CO2 concentration is measured in mole fraction instead of parts per million in this figure but the same global year to year trending is obvious, only now you can see that most of the CO2 originates in the northern hemisphere and gets distributed into the southern hemisphere by weather patterns. This characteristic is important to one of the possible solutions to Global Warming I will cover shortly. This says Mauna Loa is a representative site to measure world CO2.

Figure 2 – Global Tropospheric CO2 Mole Fraction in 2011

The Earth’s mean temperature is controlled by the thermal radiation equilibrium between the Sun’s daily radiation to the Earth’s surface and the Earth’s daily radiation back into deep space.

The Sun radiates largely in the visible wave lengths (~ 550 nanometer wavelength) and the sunlight’s energy density at the upper edge of the atmosphere is about 400 W/m2 as shown in in the upper half of Figure 3 below. Overall, the Earth reflects back about 29% of the on-coming solar radiation as is shown by the energy intensities at the surface shown in the lower half of figure 3. The fraction of solar energy absorbed in the atmosphere and at the surface is averages about 344 W/m2 and is very dependent on the cloud cover and surface conditions as shown in Figure 4 below. For long term energy equilibrium, the same 341 W/m2 needs to be reradiated back into deep space as heat in the infrared spectrum. Global Warming is caused by a buildup of greenhouse gases in the Earth’s atmosphere which are absorbing this infrared energy and requiring a higher surface temperature to achieve the 341 W/m2 average reradiation requirement.

Figure 3 – Solar Energy Densities outside the Atmosphere and at the Surface

Figure 4 – Percentage of Solar Energy Reflected for various conditions

Figure 5, below shows Earth’s average albedo for March 2005, measured by the Clouds and Earth’s Radiant Energy System (CERES) instrument aboard NASA’s Terra satellite. Albedo is the fraction of incoming sunlight that our planet reflects back to space. If Earth was covered in ice like a giant snowball, its albedo would be about 0.84, meaning it would reflect most (84 percent) of the sunlight that hit it. On the other hand, if Earth was completely covered by a dark green forest canopy, its albedo would be about 0.14, meaning most of the sunlight would get absorbed and our world would be far warmer than it is today. Satellite measurements made since the late 1970s estimate Earth’s average albedo to be about 0.27 noted earlier.

Figure 5 – Earth’s Measured Albedo

In the albedo image above, white shows areas where Earth reflected the highest percentage of shortwave solar radiation. Dark blue shows areas where Earth reflected the lowest percentage of shortwave solar radiation. Notice how the highest albedo values are in regions where Earth is mostly covered by snow and ice, or clouds, or both. The lowest albedo values occur in forest-covered landscapes or open ocean.

There are factors in Earth’s climate system that influence how much sunlight our world reflects back to space versus how much it catches and stores in the form of heat. Any significant changes in the brightness of the land surface or in the extent of clouds and aerosols in the atmosphere affect how much sunlight Earth reflects, which, in turn, affects the climate system. A drop of as little as 0.01 in Earth’s albedo would have a major warming influence on climate—roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area.

This brings me to my solution for postponing the effects of increased CO2 until we have had time to fix the problem. We need to gradually increase Earth’s albedo by 0.01 to counter the rising CO2 ppm trend until we can economically eliminate fossil fuels. How do we do that? A strong clue is the historical year without a summer, 1816. What caused this calamitous “Year Without a Summer?” At the time, many people believed the chaos was some form of divine retribution, but most scientists now place the lion’s share of the blame on an Indonesian volcano called Mount Tambora. In early 1815, Tambora roared to life with one of the most devastating volcanic eruptions on record—an explosion 10 times more powerful than Krakatoa. Along with killing thousands of locals, the blast also spewed sulfur dioxide into the stratosphere. The ash cloud drifted across the globe in the months that followed, blotting out the sun and creating a volcanic winter. When combined with the lingering effects of the Little Ice Age—a period of global cooling that lasted from the 14th to 19th centuries—the additional cloud cover was enough to lower the planet’s average temperature by about one degree F. and send weather patterns into a tailspin.

I’m not suggesting we trigger volcanic eruptions but saying that Tambora temporarily increased the cloud cover in the northern hemisphere, increasing the Earth’s albedo, and thereby reducing the temperature in the northern hemisphere (and Incidently increasing precipitation at the same time. I propose we seed clouds over the Earth’s equatorial regions to increase the albedo enough to maintain current temperatures and prevent a catastrophic melting of glacial and polar ices. This should also reduce ocean temperatures (a good thing to reduce hurricanes and cyclones) as well as reduce total Earth mean temperature.

Cloud seeding is a well-known, but generally frowned upon phenomena, because it is deemed to interfere with Mother Nature. I would propose we either modify jet fuel with additives known to seed clouds when burned or carry additives on board jetliners flying over equatorial routes and spray them into the upper atmosphere when cloud formation opportunities are available. The airlines should be reimbursed for performing this service. The best airplane exhaust product for cloud formation is probably water vapor so I would propose we rapidly switch from jet fuel to liquid methane as long-range aircraft fuel to reduce the CO2 and increase the water vapor injected at altitude. Eventually, we could go all the way to liquid hydrogen fuel for long-range aircraft and this would maximize the water vapor injected at high altitudes over the equatorial regions. The location of cloud cover and the depth of the water vapor column (depth of the total water in the atmosphere measured from ground level to space) during December 2020 is shown in figure 6 below.

This is based on satellite measurements. The upper half of the figure is measured cloud fraction where 1.0 is total cloud cover and 0.0 is clear sky. The lower half of the figure is the measured total water in a column from the surface to space in centimeters of water. Generally, the more average water vapor, the more average clouds. The other factor is air temperature which is why there or more clouds near the equator and less near the poles.

Figure 6 – Worlds Cloud Fraction and Water Vapor Column

If we modify long-range aircraft to emit less CO2 and more H2O, will it make enough of a difference to slow down the inevitable temperature rise? I don’t know, I’m still crunching the numbers, but it looks like a win-win scenario to me. As you know I’ve been very critical of the shenanigans currently underway at the behest of some politicians who are increasing energy costs by leaps and bounds while making the energy generation system less robust. I am striving to come up with practical options that reduce average costs while increasing robustness. I’ll revisit this topic is a week or two.

Good Luck and Thanks for Reading

Dana Andrews

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