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Climate Change Part 1

Updated: Nov 17, 2019

Our resident Rocket Scientist analyzed all the data available and came to the conclusion that the threat is real, but that the so-called Green Revolution is not pursuing the right strategies, and by ignoring nuclear power could even make the crisis worse.

Enclosed is a three-part blog. Part 1 explains historical climate change and how we got long ice ages with relatively short warming periods. Part 2 explains where the current global warming came from and what the true current situation is. Part 3 explains how bad it is going to get, and what we can do about it.

These blogs are not political and present the current scientific data which is sufficient to draw hard-conclusions. There is no much-discussed “tipping-point”, but if we ignore the recommendations offered, our grandchildren will be living in a physically smaller world with greatly reduced opportunities. You decide.Figure 0. Climate Change Visualized

Blog 1 - Part 1 - Historical Climate Change Explained

I have had an interest in Climate Change for several years, but I really never dug in to study it until recently. What I found was unsettling, so I’m going to share my findings. The Earth’s climate has been changing for millions of years, and up until recently the Earth has had natural safeguards that have limited the global temperature excursions to roughly plus or minus four degrees Celsius. These safeguards allowed early humans to survive and prosper through both warm spells and ice ages. Now we are told that the Earth’s Climate is on a disaster course and unless we stop the increase in Carbon Dioxide (CO2) in atmosphere, the Earth will soon be unfit to support human civilization.

Does current data and analyses really support that conclusion? Some do, and some don’t, which is why I did this study. First of all, look at the data in figure 1. What you see is that the Earth has experienced a number of temperature excursions, both warming and cooling episodes, over the past 4000 years while the CO2 level was essentially constant. I was made very aware of these temperature excursions when I visited the old family farm from 1640 across the river from Jamestown and the old original access road was partially under salt water! During the Little Ice Age in 1600s’ sea level was significantly lower. The main point I want to make is that from 1200 BC until about 1975 AD the temperature in Greenland varied appreciably and the average temperature dropped 1.5 degrees Celsius over that period while the amount of CO2 in the air over Greenland increased steadily by an insignificant amount; 5 parts per million (ppm).

Figure 1. Temperature and CO2 variations over the last 10,000 years.

Look also at figure 2 which shows the variation in temperature and CO2 over geological ages. This is equivalent to the figure Al Gore showed in his movie, “An Inconvenient Truth” in 2006.

The key point to notice is that the red line always precedes the blue line. In other words, the temperature goes up or down and then the CO2 follows. This makes sense because the Ocean holds many gigatons of dissolved CO2 and the amount varies inversely with the ocean’s temperature, i.e. a cold ocean can hold much more CO2 than a warm ocean. Hence over geological times the air and ocean temperatures changed, and CO2 would follow a few hundred years later. Al Gore has mistaken cause and effect. These two figures tell me that, historically, CO2 is not responsible for climate change. It is a greenhouse gas and plays a part, but it is not the agent driving climate change back in history.

Figure 2 Long term variations in Temperature and atmospheric CO2

As it turns out, Climate Change and our periodic Ice Ages are driven not by CO2 but by orbital mechanics! Earth’s orbit around the sun is not circular but slightly elliptic, and the Earth is not a uniform sphere so it processes around its axis of rotation on a 25,772-year cycle. The precession of the axis of rotation and slight changes in Earth’s orbit caused by Jupiter and Saturn means that for long periods summer in the northern hemisphere does not occur during the Earth’s closest approach to the sun (perihelion) and so the northern hemisphere does not receive enough solar heating during its summer to melt the ice that formed during the winter. Thus, the ice in the existing glaciers and Polar Ice Caps builds up, which increases the albedo and drives the mean temperature down even more. The reduction of CO2 during the Ice Ages is probably caused by the reduction in ocean temperature caused by extensive glacialization and remember a colder ocean adsorbs more CO2. Therefore, Ice Ages are a naturally occurring phenomena caused by precession of the Earth’s tilt in its orbit. The warm period or “interglacial period” which lasts about 12,000 of every 100,000-year cycle corresponds to the period when summer in the northern hemisphere occurs at orbit perihelion. The current interglacial period is ending, and but for the excess burning of fossil fuels, we would be experiencing the start of the next ice age right now. The process of Climate Change is shown in Figure 3 below.

Figure 3 Earth’s Temperature Variation caused by Milankovitch Cycles (from Reference 1)

The idea that orbital mechanics was driving historic Climate Change was first put forth in the 1920’s by a Serbian scientist, Milutin Milankovitch (he did his orbital mechanics research while a prisoner of war during WWI). It is now widely accepted as the driver for historical Climate Change.

Milankovitch cycles explain world temperature variations up until about 1900, but what is driving the steep temperature climb now? Could it be that the annual rate of increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases, such as those that occurred at the end of the last ice age 11,000-17,000 years ago? To tie this altogether, we need to understand the impact greenhouse gases have on Earth’s heat balance and its subsequence effect on average temperatures. The Earth absorbs solar radiation (which is centered in the visible wavelengths because the Sun’s surface is at ~ 5800 degrees Kelvin) and radiates back into deep space in the infrared (IR) wavelengths because the Earth’s average surface temperature is at ~ 280 degrees Kelvin. The amount of radiation energy an object emits, per unit surface area of the object, increases with temperature to the fourth power. This is called Stefan’s Law, after a Serbian scientist named Jozef Stefan who lived in the late 1800’s. Earth Energy Radiated = σT^4⋅(4πr2),where T is the Earth’s average Temperature, r is the Earth’s average radius, and σ is Stefan’s constant (σ = 5.670374419...×10−8 W⋅m−2⋅K−4). The thermal balance of Earth is near equilibrium (heat in equals heat out), but the greenhouse effect causes much of the outgoing radiation to warm the atmosphere, which in turn then radiates to space.

This relatively simple energy radiated relationship is complicated by the fact that not all the incident Sun’s energy makes it to the Earth’s surface (some is reflected by clouds and some is reflected by water and ice on the Earth’s surface), and only a relatively small fraction of the IR radiation from the Earth’s surface makes it to deep space (see Figure 4 below). Water and Ice plus clouds reflect approximately 30% of the incident solar radiation back into space, while approximately 80% of the radiation from the earth’s surface is absorbed before it escapes the atmosphere, and most of that absorption is by greenhouse gases and some by clouds. The heat still gets radiated to space but from the atmosphere instead of the surface.

Figure 4 Earth Energy Balance Components (from Ref 1)

Note that Figure 4 shows both the current problem and some possible ways to reduce the radiation from the sun to the surface.

The absorption characteristics for Green house gases (primarily water vapor and CO2) are shown in Figure 5 below. From Figure 5 we see that the outgoing radiation from Earth is centered at about 10 microns wavelength where water vapor, CO2, ozone, CH4, and NO3 all have partial absorption bandwidths. They are termed Greenhouse gases because the radiation energy from the Earth’s surface gets partially absorbed in the atmosphere and this maintains the current air temperature distribution. The major absorbers are water vapor and CO2 and the net result is that roughly 80% of the outgoing radiation is currently being absorbed before it can be reradiated to outer space. The increase in CO2 is increasing the amount absorbed by the atmosphere.

Figure 5 - Greenhouse Gases Absorption Characteristics (Ref 2)

For the rest of the story go to Climate Change Part 2.

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