Updated 9/21/17 for typos and the NOAA “reanalysis” of the temperature plateau.
Fundamental Climate Processes
To understand how the Greens have fallen down the rabbit hole, I need to run through a quick description of basic Earth processes as they relate to climate. The Greens tend to be highly selective in choosing the processes they care about, and they often misinterpret those they do care about.
The Earth is essentially a big rock orbiting the Sun in a vacuum. Because it is internally warmer than space, due to radioactive decay, it radiates heat into space. That heat radiation is technically known as black body radiation. With the application of some esoteric physics, scientists can predict what the surface temperature of a body would be for a given level of radiation. The models that predict such temperatures are known as black body radiation models and they provide the basis of most of the discussions of global warming.
The prediction of temperature by those models is complicated by three things: the Earth is not black; the Sun provides energy to the Earth; and the Earth has oceans and an atmosphere. These complications lead to an entire suite of rather intricate models. The first place where Green organizations dominated by meteorologists, such as the IPCC, go wrong in interpreting their models is in using the wrong temperature. They focus on the average temperature of the bottom of the Troposphere, when they should be talking about the temperature of the surface of the Earth on which we are standing. However, this misinterpretation is minor compared to other Green misinterpretations that I discuss throughout this blog.
The big problem with focusing on atmospheric temperature is that it largely ignores the oceans. As it happens, the oceans are an enormous reservoir of heat and they store nearly twenty times the amount of heat as the atmosphere. One implication of that is that the oceans ensure long term stability for climate because it takes a lot of heat to modify the oceans’ temperature by even a small amount. Without the oceans, our daily temperature would vary by 120°C from 3 AM to 3 PM. Such a differential would lead to hurricane force winds circumnavigating the Earth continuously, driven by the day/night divide. A second implication is that small changes in ocean currents that transfer heat back and forth with the atmosphere can be enormously important to climate. For example, a relatively minor increase in heat transferred from the equator to the poles can result in an Ice Age.
The real complexity lies in the models of the atmosphere because gases absorb heat. Thus gases can absorb the heat radiating from the surface of the Earth as long-wave black body radiation so that it does not escape into space. (Short-wave radiation from the Sun is not readily absorbed by atmospheric gases, so it goes directly to the surface.) That absorption is the basis of the greenhouse effect, where atmospheric gases trap heat trying to escape to space and cause the atmospheric temperature to rise, which changes our climate. However, the elevated temperature due to absorbing long-wave radiation creates an unstable energy state that causes those gasses to re-radiate the long-wave radiation in all directions. Thus almost half of the radiation absorbed is retuned to the surface of the Earth and warms it above the warming due to incoming solar radiation. In extreme cases like Venus, this feedback can lead to climates incapable of supporting life as we know it. The greenhouse effect is what the Greens are worried about when talking about global warming.
To further complicate things, different gases absorb heat at different rates. The Greens tend to focus on carbon dioxide (CO2) as a source of the greenhouse effect, but water vapor (H2O) and methane (CH4) are also important causes of the effect. To describe the greenhouse effect in the atmosphere, the Greens rely on a particular model known as the Carbon Cycle. It essentially describes how the element carbon moves back and forth between the atmosphere and the surface of the Earth, mainly though CO2. There are several sources of atmospheric CO2, such as plant and animal respiration, burning hydrocarbons, and volcanism. There are also several ways CO2 is removed from the atmosphere, such as through rainfall via solution and photosynthesis. For carbon-based life, such as ourselves, to be viable, these sources and sinks need to be roughly in balance to provide a fairly constant ongoing amount of CO2 in the atmosphere. (Without life and the greenhouse effect, the Earth would be an ice ball with an average surface temperature of -13°C.) A problem for analysis of the Carbon Cycle is that there are large delays in the cycle, because CO2 tends to stay in the atmosphere for centuries before it is removed.
At the present time the carbon cycle is out of balance, and each year the amount of CO2 in the atmosphere increases by about 1%. This is the primary concern of the Greens at IPCC, WMO, and NOAA. They see a direct correlation between rising CO2 content in the atmosphere and rising atmospheric temperature, as more black body radiation is trapped by the greenhouse effect. They see this as a major threat to our long-term survival. They predict rising sea levels as polar ice melts, and an increasingly arid climate that will greatly reduce food crops. To justify this fear, they point to mass extinctions in the past when atmospheric temperature and CO2 reached high levels — such as at the end of the Permian Period, 250m years ago, when as many as 95% of all species living at that time went extinct. The notion of a mass extinction is quite scary and the IPCC tries to present the threat of increasing CO2 and global warming in the scariest possible light. (In their zeal, they cross the line into scientific charlatanism and my last post in the blog describes a number of techniques they use to do that.)
One thing the Greens don’t tell you is that the range of CO2 that will support carbon-based life is actually quite large. Those climate-caused mass extinctions occurred when CO2 was 12-20 times greater than it is now and there was also a lot more methane in the atmosphere. They also fail to mention that current levels of CO2 are close to historic lows for the past four billion years. But I’ll have more to say about that later.
While the role of CO2 in the greenhouse effect is important and there have been climatic mass extinctions in the past, the IPCC is actually suffering from several problems in interpreting the black body radiation models and the Carbon Cycle. These are…
CO2 myopia. CO2 is not the only greenhouse gas. CO2 is a just one moderately effective greenhouse gas. It is important at the scale of millennia because of its role in the Carbon Cycle and because it is fairly common. Methane (CH4) is 72 times more effective in absorbing long-wave radiation than CO2 and nitrogen oxide (N2O3) is 230 times more effective. However, these gases are present in such small quantities (normally) that they account for only about 16% of the overall greenhouse effect at present. Curiously, the official list of greenhouse gases provided by the IPCC does not include water vapor (H2O). H2O is much less effective than CO2 but there is a lot more of it than CO2 in the atmosphere, so it currently accounts for roughly 60% of the greenhouse effect. The variability of its volume in the atmosphere makes it critical to most rapid climate changes, such as the notoriously rapid changes in temperature associated with the starting and ending of interglacial hiatuses. (I will be talking about this in the next post because we are living in such a hiatus at present).
If pressed, IPCC will justify not including H2O in their list of greenhouse gases because technically water vapor is not a gas because atmospheric temperatures are too low to support produce steam, the gaseous phase of H2O. Thus water vapor in the atmosphere is merely a suspension of liquid water molecules. I submit using this sort of pedantic quibble to justify ignoring it (I could not find a single reference to its effect on the greenhouse on the IPCC web site) is scientific charlatanism. You can’t talk about Earth’s greenhouse effect in any meaningful way without talking about water vapor. If IPCC was that concerned with technical definitions, they should have renamed their list “Greenhouse Components” and included water vapor to provide proper balance. But they didn’t because if the naïve reader does the math from their list, CO2 will seem to contribute over 70% of the greenhouse effect, which is exactly what they want you to think.
Recently the Greens have argued that the increasingly erratic weather worldwide during the past three decades is due to global warming from increased CO2 levels. That claim is completely false. Local weather is driven by temperature, water vapor, and local geography. Meteorologists have several equations that are used to explain everything from hurricanes to offshore breezes and cloud formations. Each of those equations has a term specifying water vapor content or temperature or both. None of those equations has a term specifying CO2 content. In fact, increasingly erratic weather is a harbinger of imminent rapid climate change due to changes in heat transfers between equator and poles via ocean currents, which I will have more to say about later in the blog. Note that the Earth has been warming fairly steadily for a few thousand years. If erratic weather is due to increasing atmospheric CO2 and erratic weather is driven by that, why has erratic weather only increased over the past three decades?
Assuming the natural Carbon Cycle is constant. A critical part of the Green position is that Man’s burning of hydrocarbons for energy is the sole cause of present global warming. That position is predicated on the assumption that the contributions of all the natural mechanisms of the Carbon Cycle, such as plant respiration, are constant over time. This enables the Greens to point the finger at Man for causing the current surplus, because Man has only seriously added CO2 via burning hydrocarbons since the start of the Industrial Revolution in the early 19th century. That assumption of nature being constant is simply not true and a major goal of the geological history of the Earth in the next post is to demonstrate why it is nonsense.
Ignoring the geologic record. 550 million years ago multi-cellular life became dominant on Earth. If we look at the geologic history of the Earth since that time, there are a number of inconvenient facts for the Greens. The present atmospheric temperature and CO2 content are close to historic lows for that entire time period. The only times they have been lower is during the glacial phases of our current Ice Age. The average atmospheric temperature for the Earth for the last 500 million years is about 7-10°C higher than present, including ice ages. The average CO2 content over that time is well above 3,000 ppm. Yet life thrived at the mean levels with more diversity than at present; the Earth between the 30° latitudes, north and south, was a largely a tropical paradise. At the present time we are living in the Quaternary Ice Age that began about 2.6 million years ago and will likely continue for at least another million years. There aren’t a lot of ice sheets around now because we are currently in what is technically known as an interglacial hiatus. That is a short period (usually 1-2 thousand years) of temporary warming. There have been several previous hiatuses over the past 2.6 million years and they are all essentially identical — and there are well-understood mechanisms for starting and terminating them that I will talk about in detail later.
When your only tool is a hammer, the world is full of nails. The Green’s CO2 myopia and ignorance of the geologic record are only two examples of their focus on meteorology as the solution to the world’s problems, to the exclusion of other mechanisms. In particular, the Greens see atmospheric CO2 as driving atmospheric temperature. That is true up to a point. However, if you look at long-term trends in temperature and CO2 content, temperature actually leads CO2 content by about 800 years. That is, at major climatic turning points, the temperature trend will reverse before the CO2 trend does. The reason is that climate turning points are usually triggered by other mechanisms, such as changes in atmospheric water vapor content. My point here is that the Earth is a very complex system and there are a lot of powerful forces at work that drive conditions in the atmosphere and, consequently, climate. The Greens tend to focus only on atmospheric CO2 content.
Plate Tectonics. The last point allows me to segue into a discussion of one of the most important factors in the Earth’s climate: plate tectonics. The Earth’s crust is relatively thin, ranging from 5 Km thick for oceanic crust to up to 40 Km thick for continental crust. (That may seem pretty thick but it is quite thin compared to the Earth’s 12,000 Km diameter. If the Earth were reduced to the size and mass of a chicken egg, the surface would be so smooth that it would be impossible to pick up with two fingers.) That crust literally floats on the Earth’s Upper Mantle. The Upper Mantle is quite hot and under great pressure, so it has huge convective cells where solid mantle rocks flow via plastic deformation. Those cells push the continents around like slag on top of a bucket of molten recycled iron. The movement is slow – just a few centimeters per year. However, the momentum is huge, so that when continents collide massive mountain ranges are formed. An example is the ongoing formation of the Himalayas as India continues to crash into Asia (Mount Everest has grown 27 feet in the 150 years). Plate collisions also drive major amounts of volcanism that produce greenhouse cases (for example, the famous Pacific Ring of Fire).
[Man’s recorded history has been a remarkably quiet period compared to the rest of the geologic record. For example, there has only been one supervolcano eruption, Mt. Toba in Indonesia in 999 CE, in our recorded history. A single, smallish supervolcano eruption can thrust more than three times man’s annual production of CO2 into the atmosphere. There are 26 known active supervolcanos. Plateau basalts can produce similar amounts of CO2 in almost continuous eruptions for as long a 1m years.]
The movements of continents around on the surface of the Earth are called plate tectonics (or, more popularly, continental drift). Every physical thing we observe on the surface of the Earth, from Mt. Everest to a grain of beach sand, is a product of plate tectonics. The Earth is 4 billion years old, yet there are only a handful of locations on Earth where we can actually find rocks that are more than 3 billion years old. All the other rocks have been recycled many times through what is quaintly called the Rock Cycle (see the figure below, which describes how the three major classes of rock types morph into one another via geologic processes). That recycling is the direct result plate tectonics. Even the atoms of our bodies have passed through the Rock Cycle several times.
Plate tectonics does far more than manipulate rock materials, though. There are several ways it directly affects climate. A major example is that whenever the continental land masses are bunched together at the poles, we have an ice age. In that situation, the major ocean currents tend to simply circumnavigate the planet on the equator and do not transfer any heat to polar regions, causing the polar atmospheric cells to expand towards the equator. Similarly, when continents bunch up near the equator, we tend to have a tropical paradise. (This is a somewhat oversimplified explanation because life and atmospheric Hadley Cells combine to change the heat gradient between equator and poles as the continents move.)
At a smaller scale, the mountain ranges created as plates collide deflect winds. That causes the winds to drop moisture as rain as they climb over the mountains. Thus the western part of Washington State has high rainfall but the eastern part of the state behind the Cascade Range is quite arid. Major mountain ranges, like the Himalayas, also dictate where large convective cells in the atmosphere form. That, in turn, affects rainfall and creates monsoons for fertile areas like the ‘rice bowl’ in Southeast Asia that feeds nearly 4b people.
200 million years ago there was a single huge continent called Gondwanaland located on the equator. It was crisscrossed with large mountain ranges formed by the collisions of several plates. The result was a tropical paradise with rain forests and swamps everywhere. That paradise gave birth to the dinosaurs by supporting the gigantic herbivores at the base of their food chain (though there were quite a few small dinosaurs that don’t get much press). Alas, by the end of the Cretaceous Era, 65 million years ago, that continent had broken up into the continents we know today. They were starting to drift apart and most of the mountain ranges had been eroded away, drastically reducing rainfall. The new continents had arid interiors with Saharan-like sand dunes. That climate could no longer support huge herbivores and the dinosaurs went away.
Two other mechanisms have an enormous effect on climate. They are the two most important mechanisms with respect to life as we know it and they operate in tandem to control our climate…
Photosynthesis. This is the process where CO2, H2O, and sunlight are converted to hydrocarbons. The basic reaction is:
6CO2 + 6H2O + light energy => C6H12O6 + 6O2
The reaction varies and the large molecule on the right, glucose, will be substantially different in various plants and microbes. Without photosynthesis our atmosphere would be utterly toxic to human life. All plants and most microbes on the surface of the Earth employ some form of photosynthesis, but almost no animals provide the process.
Respiration. This is the process where hydrocarbons and O2 are converted into energy for cell formation, movement, and reproduction by all living things on Earth. It is essentially the chemical process of metabolism in carbon-based living things. The basic equation is:
C6H12O6 + 6O2 => energy + 6CO2 + 6H2O
Note that this is exactly the opposite of photosynthesis. All living, carbon-based organisms require respiration for growth, reproduction, and movement.
An obvious question is: If only plants remove CO2 and produce O2 while both plants and animals remove O2 and produce CO2, why doesn’t CO2 dominate our atmosphere? The simple answer is that plants and microbes, which are not very active, do a lot more photosynthesis than they do respiration. However, that ratio depends on the type of organism. Although there are exceptions, the general rule is that faster growth and more activity requires more energy, so the metabolism of the organism will be higher and more respiration will be necessary. Similarly, animals that live on land must fight gravity to move, so they have much higher metabolisms than animals in the ocean, which require less energy to move due to neutral buoyancy. As it happens, respiration of animals on land is critical to climate. That’s why ice ages occur when land masses concentrate at the poles: lower temperatures => shorter growing seasons => fewer land animals => less respiration => lower atmospheric CO2 => Ice Age.
In my geology days, I sometimes walked across fern meadows in the tropics. The temperature in the meadow is 5-10°F warmer than the surrounding forest. In the center of the meadow, one has a stifling feeling because the CO2 produced is replacing oxygen rapidly, so you can actually feel short of breath. Ferns are a plant whose respiration is quite high. The same is true for several human food crops. In contrast, trees tend to be slow growing and have low metabolisms for their bulk, so their respiration is relatively small compared to their photosynthesis. (Sap is moved primarily through capillary transport that requires very little energy.) Trees also store large amounts of carbon from CO2 for extended periods of time, while food crops tend to store carbon for less than a year due to harvesting.
Food for thought. Plant respiration emits hundreds of billions tons of CO2 to the atmosphere each year while Man contributes only about 15 billion tons each year burning hydrocarbons for energy. For the past several centuries Man has removed forests and replaced them with high metabolism food crops and grazing grasses to feed himself. For example, the central plains states of the northern Mississippi valley were completely forested prior to European settlement. Today trees are only found there in small, isolated pockets and decorating people’s front lawns. Europe has an even larger proportion of deforestation and the same thing is happening to the Amazon rain forests. Today, more that 50% of the continental land area is devoted to farming and livestock. Is it not plausible that man’s seven-fold population growth in two centuries has more to do with increasing CO2 levels in the atmosphere than the burning of hydrocarbons? But I’m getting ahead of the story…
Oceans. The last major influence on overall climate is the oceans. I mentioned previously that heat transfers in the oceans are enormously important to climate. Winds blowing over ocean currents extract heat from the currents and distribute it elsewhere. A classic example of this is Europe. Madrid, Spain is on roughly the same latitude as New York City, yet it has a subtropical arid climate while NYC has a north temperate climate. Indeed, most of Europe is temperate despite being on the same latitudes as Newfoundland and the Northwest Territories, which have sub-arctic climates. The reason is that westerly trade winds pick up heat from the Gulf Stream in the North Atlantic and transfer it to Europe.
Most of the heat transfers that affect local climate are in circular currents called gyres. There is a gyre in every major ocean, as shown in the following diagram. These currents flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere due to trade winds driving East to West on the equator and West to East at higher latitudes. These currents exist only in the surface of the ocean, down to about 300 meters depth. They are primarily wind-driven.
There are also major vertical circulations in the ocean where water moves between the surface and deep oceans, known as the Thermo-Haline Circulation (THC). There are two major upwelling zones, where water moves from the deep ocean to the surface, and two major downwelling zones, where water moves from the surface to the deep ocean. The downwelling zones are in the North Atlantic off Scandinavia and around Antarctica. The one in the North Atlantic occurs because the Gulf Stream carries warm water with high salinity from the equator. When that water mixes with cooler Arctic waters, its salinity makes it relatively dense and it sinks into the deep ocean. A very different mechanism operates around Antarctica. A permanent wind blows around Antarctica offshore, the Antarctic Vortex. That wind drags surface water. An exotic mechanism, known as Ekman Transport, causes the water to flow towards the continent all around this circle. The water was has no place to go except down into the deep ocean. (There is also a similar density change to that in the North Atlantic as the South Australia Current carries warm, salty surface water from the equator to the Antarctic.)
Ocean ice also contributes to downwelling at the poles. Sea ice is fresh water. When it forms, the salts in the water are expelled and form a brine under the ice. That brine is cold and dense, so it sinks into the deep ocean. (This mechanism only works for new sea ice; permanent ice packs accrete ice via precipitation from the atmosphere.)
Once in the deep ocean, the downwelling currents disperse widely through the vast deep ocean, which causes them to slow down to roughly 20 Km/yr (compared to ~10 Km/hr for the Gulf Stream). So they are more properly called a ‘circulation’ by oceanographers, rather than a ‘current’. Nonetheless, the downwelling flows from the surface displace deep ocean waters, much like massive hydraulic pistons. To balance these displacements, there are two major zones of upwelling from the deep ocean to the surface, which form two major cycles in the oceans. These are roughly on the equator just off the coasts of western Africa and western South America. (There are also a number of secondary upwelling zones that are driven by things like undersea volcanism, but these usually dissipate before reaching the surface.)
The mechanism that determines the location of these upwellings, known as divergence, is interesting. The gyres in the Atlantic and Pacific oceans provide parallel East-to-West currents near the equator. However, they don’t mix because weak Coriolis forces tend to bend them both away from the equator. That divergence creates a void between them. That’s impossible in a fluid, so water must fill the void created. That water is pulled up from the deep ocean at the upwelling points. One can actually see this on satellite infrared photos as a thin line of cool water between the two warm gyre currents.
These upwellings have to be linked to the polar downwellings to balance displacements. The upwelling point off Africa is linked primarily through the Gulf Stream off the East coast of North America to the North Atlantic downwelling. The upwelling point off South America is linked to the Antarctic downwelling primarily through the South Australia Current. This overall system is known as the Thermo-Haline Circultaion (THC) The link via the Gulf Stream is the most powerful for two reasons. There is no downwelling in the North Pacific because the Bering Straight is too narrow and too shallow to allow proper mixing with cool Arctic waters. In addition, the South Australia current is limited by friction as it moves over the huge, shallow shelf of the South China Sea and around the islands of the Indonesian Archipelago. Also, the Ekman Transport mechanism is weaker than the density differential off Scandinavia, so the downwelling around Antarctica is weaker.
Normally the gyre in the North Atlantic would have a volume flux of about 20m tons/second. However, there is an additional 30m tons/second added by the Gulf Stream to balance the welling displacements. This makes the Gulf Stream the largest current in all the oceans. It is 70 Km wide and 450 m deep. Thus it carries an enormous amount of heat from the tropics to the pole. In fact, this current is critical to terminating interglacial hiatuses, which I will discuss in detail later. Terminating an even larger version of the Gulf Stream triggered the current Quaternary Ice Age, but that is getting ahead of the story.
Before leaving the subject of oceanic influences on climate, I would like to discuss one classic example of how important oceanic currents are to climate. The upwelling point off Peru enables one of the world’s best fisheries. That’s because the surfaces of the oceans are actually rather short of critical nourishment elements like phosphorus, iron, and magnesium. (In this respect they are similar to the notoriously poor soils of tropical rain forests; the profusion of life has extracted all the nourishment.) The upwellings bring these nutrients to the surface from the deep oceans. Those nutrients result in plankton blooms that support the large fishery off peru. (The Gulf Stream also carries such nutrients to the fisheries of the North Atlantic.)
Alas, there is a problem, known as the Southern Oscillation. The equatorial currents, driven by Easterly Trade Winds, pick up a lot of heat from the Sun as they cross the Pacific near the equator. That current piles up warm water in the South China Sea (literally; sea level is 2-3m higher on the Western side of the Pacific). That warmth creates a large high pressure dome in the atmosphere over that area. As that dome builds up over a few years, it gradually curtails the Easterly Trade Winds. Eventually the Trade Winds weaken enough so that gravity wins out and the higher sea level in the West evens out with warm water flowing back across the Pacific to Peru. That warm water shuts down the upwelling and the plankton bloom dies, creating an economic disaster for Peru.
This phenomenon of warm water moving back to Peru is known as El Nino. I mention it because it has far wider effects on climate than just the Peruvian fishing industry. El Nino has been linked to worldwide climate effects, such a increased frequency of hurricanes in the Atlantic and droughts in the US Southwest. That’s because when the Pacific Trade Winds are curtailed, the atmosphere has to adjust its own thermal displacements, which has far reaching effects — all because of a partial reversal of the South Australia Current. (The atmosphere is a chaotic system in a mathematical sense. One property of such systems is that a small push in one place can sometimes produce a major change a long distance away.)
There is a lesson to be learned from all this. Despite the myopic view of some meteorologists, now calling themselves climate scientists, the atmosphere only effects local weather, like tornados and floods. It has very little to do with the overall climate of the Earth (aside from ozone formation). Things like the greenhouse effect are actually driven by surface mechanisms, like photosynthesis and respiration, that add and remove greenhouse gases. Similarly, major atmospheric heat transfers are primarily driven by ocean currents. Finally, plate tectonics determines where major atmospheric convection cells live and where permanent climate features, like monsoons, do their thing.
Recently the weather has become more erratic; the ’00s decade had the most erratic weather worldwide in recorded history. The Greens have latched onto this and claimed it is just another example of the effects of global warming through increased atmospheric CO2 content. That is just plain wrong. Local weather is driven by solely by temperature and moisture content. All the equations that describe thunderstorms, tornadoes, monsoons, hurricanes, and even summer offshore breezes are dominated by moisture content and temperature terms. Those equations do not have any terms for CO2 content.
Erratic weather started in the mid-’80s and has been steadily increasing in severity since then. However, global warming began 10,000 years ago and has risen 7°C since then, while temperature has increased only slightly since the mid-’80s and not at all in the past 15 years. So what really happened in the mid-’80s to trigger erratic weather? The Gulf Stream began to shut down and the North Atlantic began to cool. That has caused the atmosphere to make adjustments for the reduced evaporation there and, much like El Nino, that has far-reaching effects. In fact, the oceanographer’s models back in the ’80s predicted erratic weather as a harbinger of a return to the depths of the ice age when the Gulf Stream shut down. In other words, attributing current erratic weather to increasing CO2 is utter nonsense.
The oceans are also the driver for rapid climate change. That is because of a mechanism known as positive feedback. Almost all of the moisture in the atmosphere is provided by evaporation of the oceans. The rate at which oceans evaporate depends primarily on surface temperature. At 0°C evaporation is near nil. The evaporation plateaus a little over 50°C because there is a physical limit to how much water vapor the atmosphere can carry at a given temperature. Evaporation rises in a nonlinear fashion from 0°C until it becomes asymptotic to the saturation maximum in a flattened ‘S’ curve. The evaporation curve changes most rapidly in our “normal” climate temperature range of 10-20°C.
This is critically important to climate. If the surface temperature rises significantly, say due to a sudden introduction of CO2 in a volcanic eruption, the oceanic evaporation rate will increase. That increase puts more water vapor into the atmosphere than normal. That sudden addition of water vapor, as a greenhouse component, raises the surface temperature another increment. That increment, in turn, increases the evaporation rate, which puts more water vapor in the atmosphere, and so on. This cycle is a positive feedback loop that can raise the Earth’s temperature very rapidly over several degrees in a few decades. That large, sudden rise has nothing to due with atmospheric CO2, other than the initial, triggering increment in surface temperature from the eruption. This is the primary mechanism for initiating interglacial hiatuses very rapidly. A super volcano raises the temperature 0.5°C or so. That triggers positive feedback in evaporation to raise the temperature another 6-7°C.
The same mechanism can operate in reverse to cool the Earth very rapidly. However, changes in CO2 cannot trigger such decreasing rapid climate change because there is no mechanism to suddenly decrease atmospheric CO2 as a trigger mechanism like volcanism raises it. The only way to trigger decreasing rapid climate change today is to have a catastrophic shutdown of the THC. That has happened several times in the past 800,000 years when several interglacial hiatuses were terminated by rapid climate change. When that happens, the heat transfer from the equator to the North Atlantic essentially stops and the North Atlantic experiences a sudden cooling. That sudden cooling triggers the positive feedback for a downward spiral in temperature.
Ironically, the catastrophic shutdown of the Gulf Stream is, itself, triggered by global warming. As the interglacial hiatus rapidly warms, the summers in Greenland become longer and warmer. Greenland has massive ice sheets that have been accumulating for 2.6m years. Eventually the warming leads to a tipping point where Greenland switches over from net annual accretion for snow and ice to a net annual melting of snow and ice. That releases fresh water into the North Atlantic. The Gulf Stream flows past the southern tip of Greenland, so that fresh water dilutes it at an increasing rate as the summers lengthen and warm. That dilution of the Gulf Stream’s salinity weakens the hydraulic piston effect at the downwelling point off Scandinavia. Eventually the Gulf Stream can no longer sink to the abyssal layer of the North Atlantic and the circulation of that portion of the THC is broken. That triggers a variety of other mechanisms that accelerate the temperature decline (e.g., longer winters in Europe increase the Earth’s albedo there and more sunlight is reflected directly back into space without warming the Earth’s surface). Those effects radiate out over the Northern Hemisphere. This results in an immediate drop of 3-5°C in Earth’s average temperature in 50-80 years. (The rate of cooling slows down then since it takes longer for ice sheets to cover the continents and increase the Earth’s albedo, so it takes another few thousand years to complete the return to the depths of the glacial phase of the Quaternary Ice Age.)
- The Earth’s present average surface temperature is at the tipping point and strong evidence indicates the Gulf Stream started its catastrophic shutdown in the late ’80s. The evidence is:
- The salinity of the Gulf Stream off Scandinavia began to decline at an increasing rate in the late ’80s.
- Erratic weather in response to reduced heat transfers in the North Atlantic has been increasing since the early ’90s
- Oceanographers making direct in situ measurements of the Gulf Stream’s volume flux (the amount of water flowing through a cross section per unit time) determined that the volume flux decreased a little over 30% in the ’00s decade.
- Atmospheric temperature has ceased increasing since the mid-90s, despite the fact that Man added 40% of the CO2 from burning hydrocarbons for the entire Industrial Revolution in just the ’00s decade as India and China became major industrialized nations without great concerns over pollution.
- In 2014 it was determined that the middle layers (1,500-3,000m) of the North Atlantic and Indian oceans suddenly began warming rapidly. This essentially means the Gulf Stream and South Australia Current can no longer penetrate to the abyssal layer of the ocean and are dissipating in the middle layer. IOW, the THC circulation has been broken. (The Gulf Stream and South Australia Currents will continue to run for another 1-2 decades because the inertia of the small pressure differentials that drive the flow will take that long to dissipate.)
The Greens are in a state of complete denial over this. They have offered several examples of scientific charlatanism to refute this possibility and it is interesting to look at them. I have already mentioned their claim that erratic weather is due to adding CO2 to the atmosphere. In fact, erratic weather is due to changes in winds, currents, and evaporation rates due to a reduction in heat flow from the equator to the North Atlantic.
The IPCC responds to the reduced volume flux with two papers that conclude the changes are “within normal variance”. One paper measured the surface velocity while the other did a statistical analysis of satellite radar imaging to determine sea level (because the Gulf Stream is relatively buoyant, it does bulge up above the water around it). The IPCC does not reference the oceanographer’s measurements. The oceanographers measured the flux by driving a boat across the Gulf Stream. The boat dragged a cable that extended to below the Gulf Stream and that cable had a bunch of flow meters spaced along it. Which measurements do you find most compelling? Why didn’t they even cite the oceanographer’s results?
The flat temperature for the past couple of decades is a really big problem for the Greens, given the 1% annual increase in CO2. One Green noted the rise in temperature in the middle layer of the North Atlantic and announced that the heat needed for that rise was the same as the heat the increasing CO2 would have added. Therefore, the heat went into the middle layer of the North Atlantic to account for the flat atmospheric temperature. Thus global warming was still happening. When I read this I laughed so hard that my sides hurt. Global warming is global because CO2 is distributed fairly evenly in the atmosphere. So why did the heat go into only the North Atlantic and Indian oceans? Why did it only start going there in the past few years when the climate has been warming steadily for two centuries? What heat teleportation mechanism got the heat from the atmosphere to the middle layers of the North Atlantic and Indian oceans without changing the temperature of the upper layer of those oceans? In fact, we know how the Middle layer is warming and it has nothing at all to do with global warming.
Recently a study was released by the Greens where they “reanalyzed” the temperature data for the past three decades and concluded that the temperature was not flat; it was actually warming. It turns out that they didn’t reanalyze the data; they just added weather stations and recomputed the average. If one wants to directly measure the average temperature of the whole Earth, one needs to section up the Earth’s surface by small, equal-area grid squares. One then takes the data from a weather station in each grid square, sums it up with the other squares and computes the average. There are complications because not all of the squares have weather stations and some squares may have diverse climates. You can deal with these problems with interpolation or using multiple weather stations in the squares (so long as you have the same number of stations in each square). That gives you a fair sampling of temperatures over the entire surface of the Earth.
The Earth does not warm uniformly. For example, the poles usually warm or cool much faster than the equator. So where did the Greens add their weather stations? They added most of them in areas of highest warming. Thus they deliberately biased the sampling to favor warming. Additionally, NOAA sponsored the “reanalysis”, but curiously the 1500+ deep ocean weather buoys they deploy along the equator, where temperature varies very little, were not added. In my opinion, that goes beyond scientific charlatanism into scientific fraud.
NOAA switched databases from CHGN to ISITI for the reanalysis (ISTI is a superset of CHGN). I went to the ISTI web site and found a bunch of diagrams that proved what they had done. Each diagram was a map of the world with colored dots showing where stations had been added. (The color coding was for the source of the station data.) There was one diagram for each update of the database, so walking through the diagrams in time clearly showed the addition of stations in high warming areas.
I mentioned this to an old college friend who followed up by talking to a Green who utilized the ISTI heavily and also had connections to NOAA. That Green replied that the sampling was not a problem because different groups used subsets of the data tailored to their specific purposes, implying that the “reanalysis” people would select a proper sample for their purpose. When my friend relayed that answer back, it did not give me a warm and fuzzy feeling because eliminating the temperature plateau seems like a pretty powerful purpose to me.
But the story doesn’t end there. A month or so later I referred someone else to the ISTI data, but they couldn’t find it. Those diagrams I had looked at are gone. In their place is a single page with a table listing sources, dates, and number of stations added for each update without any location data. The page was clearly a rush job because it did not fit in the web frame and there were no scroll bars to access portions that were not visible. In other words, not only did they cook the data, they also covered it up when they got caught at it.