Editor's Note: Biographical Sketch
Glenn Tamblyn is a degree-qualified mechanical engineer with a 30-year career in engineering, IT, and solar energy research. Having studied climate science for eight years, he is pursuing action to reduce the impact of anthropogenic global warming. Tamblyn received his degree from Melbourne University, Professor Karoly's university. He is co-author, with John Mason and Rob Painting, of Introducing Climate Science (Dunedin Academic Press, in press), a contributor to online courses about climate change, a team member in the climate science literature review Cook et al., 2013, and a contributing author at the website Skeptical Science.
Perhaps before proceeding to talk about global warming and climate change, let's first consider what climate itself is.
Climate is the average of the weather, the average state of various weather parameters such as temperature, rainfall, seasonal cycles, etc. Not just the surface, it is also what happens in the stratosphere, the state of sea ice in the Arctic, and other phenomena beyond our day-to-day experience. We also need to understand what timescale the weather is averaged over. As defined by the World Meteorological Organization and actually first used by its predecessor, the International Meteorological Organization, before WWII, climate is the 30-year average of the weather. This isn't an arbitrary definition, but was calculated from the statistics of weather data. Thus changes over a few years are not climate changes, they are just natural variability, something within the climate.
Importantly, we need to distinguish between those aspects of the system that are of relevance to us where we live, mainly atmospheric conditions, and those aspects that actually govern what happens and why, the mechanisms. We may not live hundreds of meters beneath the surface of the ocean, but it certainly plays a big part in what happens and why. Let's start with those things furthest from our direct experience: the climate of the entire planet.
The Sun radiates vast amounts of energy in all directions every second, and has done so for billions of years. It is surprisingly stable in its heat output, only showing a small variation of less than 0.05% in heat output over roughly an 11-year cycle, the sunspot cycle. Of the small part of this energy that arrives at the Earth, roughly 30% of this is reflected by the Earth from clouds, snow and ice, etc. Reflected sunlight is not absorbed and does not contribute to warming the planet. The 70% that is absorbed does.
This rate of heating is approximately 239 watts for every square meter of the Earth's surface. Over the Earth's entire surface, this adds up to over 120,000 trillion watts. In contrast, all human energy consumption is at a rate of 18 trillion watts. Heat from the Sun is the “main game” for climate.
If the Earth absorbed this heat and retained it — if it all accumulated here — this rate would boil the oceans dry in less than 1000 years. That obviously hasn't happened. The reason is because the Earth also radiates heat out to space as infrared radiation, balancing the incoming flow. When these flows balance, the Earth neither warms nor cools. This is an exquisite balance; even a 1% imbalance would still boil the oceans in 100,000 years. This balance is dynamic; the daily and seasonal cycles, even the 11-year sunspot cycle, all cause the system to cycle around this balance. But they cancel out and the long-term average rarely changes.
Professor Happer calculated the expected average temperature of the Earth using the Stefan-Boltzmann equation, arriving at a figure of 5° C. However his calculation contains a significant error: He doesn't account for the 30% of sunlight that is reflected and is not absorbed! The Earth does not need to radiate as much as his calculation suggests and when we redo the calculation accounting for this, the average temperature the Earth needs to be at to balance incoming solar radiation is −18° C.
But the surface is at around 15° C! The surface of the Earth is over 30° C warmer than we might expect due to simple energy balance alone, not the 9° C Professor Happer calculated. The greenhouse effect explains this.
In his Statement, Professor Happer gives a detailed explanation of the radiative physics of much of this, but omits discussion of one important point. In his Figure 5 he shows the vertical temperature profile of the atmosphere, including how the air temperature drops as we rise from the surface. This is the Environmental Lapse Rate (ELR), with an average value is −6.5° C/km of altitude.
This arises because of what happens when air parcels rise or fall. Gases can expand and contract and the density in the atmosphere varies hugely with altitude. A parcel of air moving up into a region of lower pressure and density must equalize pressure with the air around it, so it expands as it rises. However, the parcel needs to push other air parcels aside to make room for its expansion. It needs to do work on them to move them aside, and this requires more energy.
If the parcel cannot obtain any additional energy from outside — that is, if it is an adiabatic process — then the only source of energy to do this work is its own internal energy. Its internal energy is drawn down in order to power its expansion, and thus its temperature drops as it rises. This is an example of adiabatic expansion. The rate of this change is approximately −9.8° C per km and is called the Dry Adiabatic Lapse Rate (DALR). Similarly, a descending air parcel will be compressed by the air parcels around it as it descends, warming at 9.8° C/km.
A cooling air parcel may approach the dew point: some of the water vapor within the parcel starts to condense. Condensation releases heat, so now the rise of the air parcel isn't strictly adiabatic, there is this additional heat source. As a result, the parcel doesn't cool as much when it rises. This is called the Moist Adiabatic Lapse Rate (MALR) and is typically −5° C/km, varying somewhat with the temperature of the air.
So the real-world atmosphere consists of rising air parcels cooling at −9.8° C/km when condensation isn't happening (and at approximately −5° C/km when condensation is occurring), and falling air parcels that warm at 9.8° C/km. The aggregate of all these vertical movements produces the observed average ELR of −6.5° C/km.
A key feature of the lapse rate is that it arises as a result of dynamic vertical air movements. Rising and falling air actively generates the vertical temperature profile seen in Professor Happer's Figure 5. This active energy transport system drives the atmosphere towards having this vertical profile. This arises from quite simple fluid mechanics, nothing more complex than the Ideal Gas Law. We don't need to solve the Navier-Stokes equations to arrive at this result.
As Professor Happer describes, most of the infrared radiation emitted from the surface is absorbed by the greenhouse gases in the atmosphere; only 10% escapes directly to space. So how does the bulk of the energy from the surface eventually reach space? Higher in the atmosphere the air thins, the number of greenhouse molecules in the air column above drops, and infrared radiation emitted by the atmosphere starts to be able to escape to space. This is where most of the radiation recorded in Professor Happer's Figure 8 is coming from, higher in the atmosphere. Importantly, the altitude of this transition differs for each wavelength, depending on the absorption properties of the greenhouse gas molecules at each wavelength. This gives rise to the complex structure we see in Professor Happer's Figure 8.
Summarizing, when the quantity of greenhouse gases is high enough — in denser, low altitude air — radiation is an efficient means of moving energy from the surface into the atmosphere, but is a very inefficient means of moving energy around within the lower atmosphere. Air movements and condensation are the main movers of energy within the lower atmosphere. In the upper atmosphere, low air density reduces the efficiency of heat transfer by air movements, but now radiation becomes efficient at transporting heat out of the atmosphere to space.
Despite the wavelength-dependent aspect, we can still talk about the average altitude at which emissions to space arise: the average emission altitude. Currently, this is at around 5 km up. A calculation shows that with an average surface temperature of 15° C and an ELR of −6.5/km, the average temperature 5 km up is around −17.5 C: the temperature needed to keep the Earth in radiative balance! This is no coincidence — this is the greenhouse effect.
From energy balance, this average emission altitude needs to be at −18° C; otherwise, the system will warm or cool until that altitude is at −18° C. The energy transport system of vertical air movement will create a Lapse Rate profile around this balance temperature, adjusting temperatures above and below this point. The surface temperature is at 15° C because the temperature 5 km up tends towards −18° C for energy balance; the ELR then drives the surface to be around 33° C warmer. Similarly, the temperature 10 km up is around −51° C, again driven by the ELR, adjusting temperatures around the balance altitude.
Venus shows how powerful the greenhouse effect can be. With a super dense atmosphere of nearly pure CO2, the effective emission altitude is over 50 km up. Closer to the Sun than the Earth, sunlight is twice as intense, but Venus has a dense cloud layer that reflects so much sunlight that the balance temperature is −50 to −60° C. With virtually no water vapor, there is no condensation and the DALR applies, which is 10.2 to 10.4. All this produces a surface temperature more than 500° C warmer than that of the effective emission level.
Venus has a super greenhouse effect because its emissions to space come from so far above its surface. A greenhouse effect can be of any strength, all dependent on how high the effective emission altitude is.
We can do a what-if calculation here on Earth. Let's add greenhouse gases to the atmosphere, lifting the average emission altitude to 5.5 km. On average this level is −6.5 × 0.5 or 3.25° C colder than the 5 km level, at −21.25° C. Emissions to space have reduced because they are coming from colder regions. If no other factors changed, the temperature at this level would need to warm to −18° C to bring the Earth back into energy balance. And the ELR would now propagate this temperature up and down the air column, and the average surface temperature would rise to 18.25° C.
This picture is the average: the system still has all the dynamic behavior of weather, day and night, the seasons, and other cyclical processes. But underpinning all this, the common balance point that all of these cycles pivot around is warmer. If other factors impacting the global balance don't change, all the other processes of the climate adjust around this new balance point. This is “global warming.”
So, what factors might impact this global balance? There are only three things that can: the Sun, the Earth's reflectivity, or the strength of the greenhouse effect. Only these factors can impact on climate at the largest, global energy balance scale. Other factors come into play at smaller scales or shorter time periods, but they can't directly influence the big picture. At most, they can indirectly contribute to changing reflectivity or the greenhouse effect.
The Sun's warming or cooling would alter the balance. But we don't influence the Sun. And observations of the Sun for nearly 40 years show it is not warming; if anything it is cooling very, very slightly.
If the reflectivity of the Earth changed that would influence the balance, and changes in the climate can influence reflectivity. Changes in cloud cover might also influence the strength of the greenhouse effect, but this in turn needs to be caused by something else. Finally, changing the quantities of greenhouse gases in the atmosphere can influence the balance. And we are doing that:
- CO2 levels have risen from burning of fossil fuels, land clearance, and agriculture.
- Methane (CH4) levels have risen due to our emissions, land use changes (such as rice production), ruminant animals (such as cows), and changes in wetlands.
- Nitrous oxide (N2O) levels have risen because we use nitrogenous fertilizers for our crops.
- Various man-made chemicals such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6) have been added to the air.
Finally, there is the other key greenhouse gas, water vapor. This the most important of the greenhouse gases, contributing approximately 50% to the greenhouse effect, in contrast to the preceding substances that contribute around 25% (clouds are the remaining 25%). Water vapor is the largest positive feedback in the climate system, multiplying the impact of the preceding gases.
Professor Happer doesn't believe that water vapor can have this role, and thinks that as a result climate change will not be very significant in scale. Unfortunately, the professor is incorrect and perhaps should revisit his understanding of the behavior of water.
Water evaporates primarily from the ocean, entering the atmosphere as water vapor. This remains in the lower atmosphere for a short time before condensing to form clouds and returning to the surface as precipitation, mostly back into the oceans, thus closing the “hydrological cycle.” The average residence time of water vapor in the atmosphere is 1.5–2 weeks, cycling through the system quickly.
Air at a particular temperature and pressure can only hold a maximum amount of water vapor before some of it starts to condense. This is extremely well understood and documented, known to most engineers in the world, and is based on applying the Clausius/Clapeyron equation. This maximum carrying capacity rises by approximately 7% for each° C in temperature.
Absolute humidity is the mass of water vapor present in a volume of air. Relative humidity (RH) — which is the value we see on the nightly weather forecast — is a percentage, the amount of water vapor present in a parcel of air relative to the maximum amount of water vapor that parcel can hold before condensation starts.
For example, at 32° C and sea level pressure, a parcel of air that contains 15 grams of water vapor per kg of air has a relative humidity of 50%. Cool that parcel to 20° C and it still contains 15 grams of water vapor, but now its RH is 100% because the maximum the parcel can hold has reduced. Cool it any further and some of the water vapor starts to condense.
Equally important, if an air mass does not cool enough, condensation cannot start. The threshold between condensing and not is very tight. When the air is cold enough, some condensation must happen. Think of our warm moist breath on a frosty morning: we can't stop it fogging up; later in the day, when the air has warmed, nothing we do can make our breath fog up.
The same thing applies in the formation of clouds. If RH is above 100%, some clouds must form. Slightly below 100%, clouds cannot form. But to close the hydrological cycle, clouds must form and precipitation must happen. Evaporation keeps adding water to the atmosphere until there is enough to bring the RH to 100%, in enough regions, at their current air temperature, to form enough clouds and start the rain. If the air temperature is higher, the amount of water vapor needed in the air for cloud formation and rain is higher and evaporation supplies this.
Although the physics of what types of clouds form where and why is quite complex, this basic requirement dominates: globally there will be enough water vapor in the atmosphere to balance the hydrological cycle based on the temperature of the air. If there isn't, evaporation corrects that in days. Similarly, if there is too much water vapor, increased precipitation restores the hydrological balance.
If the atmosphere's average temperature changes, the water vapor content also changes, adjusting in hours or days — which is just what is observed. On time scales from hours to seasonal cycles, water vapor content responds strongly to air temperature. When large volcanic eruptions occur, such as Mt. Pinatubo in the Philippines in June 1991, their ash clouds cool the weather system. Water vapor levels fall in consequence till the ash cloud clears. Water vapor is a sensitive feedback.
Thus, the total water vapor content of the atmosphere increases in a warmer atmosphere. Since water is a greenhouse gas, this means that it will respond strongly to any other factors that cause warming or cooling of the atmosphere — whether changes in other greenhouse gases, changes in aerosols such as from volcanoes or human pollution, or changes in surface reflectivity — thus modifying the strength of the greenhouse effect.
Professor Happer cites a graph from Fyfe et al. suggesting climate models overestimate warming. The most recent IPCC report considered this in more detail as shown by the following graph:
The first graph in the top left matches Professor Happer's graph from 1998 to 2012: climate models showing more warming than observed. The second shows the years immediately before 1998, where climate models show somewhat less warming. Finally, the graph on the top right shows good agreement between the models and observations over a longer period, more than half a century. 1998 was an extremely warm, El Niño year, so temperatures afterward will appear muted by comparison. Similarly, the years just before 1998 will look overly warm because of that year. The real problem is that this is too short a period to draw conclusions about climate at all — remember, climate is the average over 30 years or more!
The bottom row illustrates this: average vs observed variability over the same periods. The models show greater differences in variability over short, sub-climate time scales, but very good agreement when considered over the correct time scale.
So, drawing conclusions about climate sensitivity (CS) from this short period is wrong; it is too short a time scale.
Here is the actual surface temperature vs. modeled results for a century or more, also from the IPCC, including the timing of major eruptions:
So, more broadly, what does the full range of science tell us about the likely climate sensitivity? From the most recent IPCC report, we have the following estimates of Equilibrium Climate Sensitivity from many sources, not just climate models:
No support here for Professor Happer's view that CS is low. Most results still cluster at a mid-point of around 3.
One study is of particular interest, the PALAEOSENS (2012) study. This looked at climate over geological ages past, stretching back 420 million years ago, in order to estimate actual sensitivity. Since this is what the climate actually did, this helps resolve questions about what feedbacks and so forth will actually do.
The first graph, from the PALAEOSENS Project, is the result of several dozen studies estimating how sensitive past climates were to any form of “radiative forcing” — a change in the energy balance. There are a few outlier studies suggesting significantly high sensitivity, but most fall fairly well within a band. The second graph applies the forcing due to a doubling of CO2 concentrations — 3.7 watts/m2 — to the first graph, giving the equilibrium climate sensitivity, while ignoring the outlier results. These results mainly fall within the 2.0–4.5 band, but substantially centered around 3.
Mother Nature — and the actual climate history of the planet — don't agree with professor Happer, it seems!
Professor Happer has used the term “bogeymen,” but perhaps a better description might be: “I don't understand this.” Let us look more closely at some of his examples.
The Professor goes into a lengthy digression discussing pollution, how much CO2 is in our breath, smokestacks, etc., while completely missing the point. The following definition might illuminate this:
(g) The term “air pollutant” means any air pollution agent or combination of such agents, including any physical, chemical, biological, radioactive (including source material, special nuclear material, and byproduct material) substance or matter which is emitted into or otherwise enters the ambient air. Such term includes any precursors to the formation of any air pollutant, to the extent the Administrator has identified such precursor or precursors for the particular purpose for which the term “air pollutant” is used.
(h) All language referring to effects on welfare includes, but is not limited to, effects on soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on economic values and on personal comfort and well-being, whether caused by transformation, conversion, or combination with other air pollutants (my emphasis).
Similarly, the concept of “thermal pollution” is well established in water management. So, if a substance is released into the air, causes warming of the oceans, and results in bleaching of coral reefs — as is happening around the world right now and has just happened on a large scale to the Great Barrier Reef two years in a row, harming ecosystems, tourism, fishing, etc. — such a substance would exactly match the definition of pollution.
Put quite simply, something is a pollutant if its addition beyond some safe limit causes harm by any mechanism, direct or indirect. It is not merely confined to just direct biological harm to individuals through direct ingestion or inhalation.
Professor Happer's digression into this “argument” is a complete irrelevancy and one wonders what his purpose was.
In his Statement, the Professor makes this very curious statement:
But as you can see from Figure 18, the world has continued to produce extreme events at the same rate it always has, . . . (my emphasis)
Then he shows two graphs for the United States (less than 2% of “the world”), one for hurricanes in the Atlantic Basin (really, the North Atlantic since hurricanes are virtually unknown in the south, so 8.1% of “the world”). Hardly the world at all. Finally, a graph of Northern Hemisphere snow cover for just one quarter of the year. Quite cherry-picked data, surely.
Let's examine this last one in more detail. The graph the professor shows is from the Rutgers University Snow Lab. Although a noisy signal, the graph shows a slight increase in snow cover across the Northern Hemisphere in winter. Rutgers also produces graphs for fall and spring. Here are all three:
1.5 million km2 more snow in fall, 0.8 more in winter, but 3.0 less in spring. So, more snow falling in fall and winter, but progressively less and less snow remaining going into summer, and less snow overall. Not quite the picture the Professor's more limited picture suggests. What does this tell us? The variation in snow cover over the course of a year is increasing. Greater melt-water volumes, larger river flows, potentially more flooding. Also less snow being held back as snow pack for as long, reducing the natural dam that Mother Nature provides to release water more slowly.
There is some more snow during the dark winter months, reflecting a little more sunlight. But during the bright summer months there is a larger decrease in reflection, absorbing more sunlight. Result: a positive climate feedback, particularly when combined with the decline in the area of Arctic Sea ice during the bright summer months over the same period.
Professor Happer next looks at sea level: the rate of sea-level rise has risen over the twentieth and into the twenty-first century. The average over that period was 1.7 mm/yr, but that rate has risen in recent decades to 3.4 mm/yr, indicating a rising trend. Then he suggests that a representative sea-level rise over another century might then be 20 cm, based solely on the past trend. But he is not asking the questions, “Why is sea level rising?,” and “How should we factor this into our projections?”
Most sea-level rise until recent decades has been due to heating of the oceans, causing them to expand slightly, and to melting of ordinary glaciers, such as in Alaska and the Himalayas, adding water to the oceans. But in recent decades melting of ice from Greenland and Antarctica has started adding to this. Which is profoundly important.
Greenland and Antarctica contain vast quantities of ice, enough to raise sea level by 65–70 meters if it were all to melt. What they may do in the future is the main game as far as sea level is concerned. Over the glacial cycles in the past, sea level has varied by 120–140 meters — we are at nearly the high point at present — due to the melting of the great ice sheets. Sea level is essentially about the great ice sheets and “other trivial stuff.”
So, how does projecting into the future based on a past period when these large “players” weren't involved constitute a sensible projection? If you build a bonfire from some paper, then kindling, then larger timbers, then finally large logs, would you predict how big the fire will become just from what the paper and kindling alone have done initially?
The history of predictions of sea-level rise has essentially been the history of the advances in glaciology. In the Fourth IPCC report in 2007, the science of glaciology was considered still immature; it was felt that it could not yet provide any reliable estimates. So, the 2007 report explicitly excluded any contribution from Greenland and Antarctica to sea-level rise projections. Not that there would be none, but that they couldn't be estimated at that time. By the time of the Fifth report in 2013, this had improved significantly and larger estimates were included, up to nearly 1 meter by the end of the century. Since then, glaciology has made major advances.
- A major mechanism driving the catastrophic collapse of floating ice shelves has been identified: crack propagation due to buoyancy changes when melt-ponds on the ice drain to the sea below.
- A major mechanism of instability when ice sheets, grounded on the sea floor and in contact with the ocean, reach a critical thickness above 900 meters has been identified. Insufficient strength in the ice means large sections can break off and float away far more easily, both above the water-line, then from below the water-line, due to unbalanced buoyancy forces. Then the process repeats. This mechanism can hugely accelerate the break-up and floating away of major marine terminating ice sheets.
- Melting of freshwater ice producing “lensing” effects on the ocean where fresher, colder, low-density water “floats” above warmer but saltier water hundreds of meters below, trapping relatively warmer water at a depth where it can melt the base of marine terminating ice sheets.
- Newly discovered below-sea-level basins and inlets in East Antarctica, in addition to the already known below-sea-level regions of West Antarctica, that are also vulnerable to these types of acceleration processes affecting ice in contact with the ocean.
These discoveries and more are all pointing to major sections of the great ice sheets that are more vulnerable to accelerated retreat than previously thought. These discoveries are matching observations from the sea floor of “ice-rafted debris” showing that past ice retreats have not been even or steady, but rather are very discontinuous, with periods where major ice loss occurs.
Studies of sea level in the past are not encouraging. The previous inter-glacial period, the Eemian 125,000 years ago, was about the same temperature as today, and sea levels were 5–9 meter higher. A study of “fossil beaches” in Western Australian suggests sea level was 5 meters higher than today for much of the Eemian, and that it quickly rose another 4 meters at the end, matching the discontinuous nature of ice retreat from other studies. The last time CO2 levels were commonly around 400 ppm was 3 million years ago during the Pliocene period. Ice age cycles still occurred but the warm inter-glacial periods were maybe 2–3° C warmer than today, and sea level was 10–20 meters higher. If CO2 levels remain at current levels for long enough, why wouldn't this happen again?
The evidence is accumulating that we have already locked in many, many meters of sea-level rise in the centuries ahead. It won't happen overnight, but rates of rise of several meters in decades are considered a possibility in the next century and beyond. And the list of what we can lose with that much rise includes:
- The Nile, Mekong and Ganges deltas — all major farming regions (the Nile delta is two thirds of Egypt's farmland).
- Miami and southern Florida. Miami is already installing pumping systems and raising road levels to cope with flooding during peak tides.
- The storm-water, sewer, and underground rail systems of many coastal cities.
- Much of Denmark.
- Lower Manhattan.
- The Netherlands.
All the downsides — all the uncertainties regarding sea-level rise — are that it could be worse than previously expected. Uncertainty isn't our friend. And why would we think it couldn't happen? It would be just a repeat of what has happened before.
The Professor doesn't seem to be aware that the main issue with changes in the pH of the ocean is from indirect impacts, not pH change itself. Small changes in pH are unlikely to have a major biological impact directly, although we should be prepared for some surprises here. In the body, blood pH needs to remain between 7.45 and 7.35; pH below 7.35 constitutes the medical condition of acidosis. Changes in ocean pH may make life harder for many creatures.
However, the main impact of adding CO2 to the oceans is in the chemistry of carbonate.
CO2 dissolving in sea water (and even in raindrops) starts a chain of chemical reactions:
CO2 ⇌ CO2 (aqueous)
The CO2 then reacts with the water to produce a weak acid, carbonic acid (H2CO3).
CO2 + H2O ⇌ CO3H2
Carbonic acid then dissociates to produce a negatively charged bicarbonate ion and a positive hydrogen ion — this is what lowers the pH:
CO3H2 ⇌ CO3H- + H+
Then the bicarbonate ion further dissociates to produce a double negatively charged carbonate ion and another hydrogen ion — more pH reduction:
CO3H- ⇌ CO32- + H+
Finally, the carbonate ion can combine with dissolved ions such as calcium and silicate to produce materials such a calcium carbonate (CaCO3), either as limestone on the sea floor or incorporated into the shells of marine creatures:
CO32- + Ca2+ ⇌ CaCO3
Like most chemical reactions, these different substances exist in a chemical balance, with some of each form present. And how much of each form exists depends on the pH of the sea water. A Bjerrum plot is a way of showing how the proportions of the different forms depends on pH. The figure below shows a simple, schematic example. Note that the vertical scale is logarithmic.
As pH decreases, the proportion of carbonate (CO32-) decreases. Adding CO2 tends to lower pH by adding the hydrogen ions from Equations 3 and 4; however, additional changes happen. Some of those hydrogen ions react with the preexisting carbonate ions to produce more bicarbonate — the reverse reaction of Equation 4. The proportion of carbonate declines even as the total of all carbon species increases.
Importantly, many other materials in the ocean also contribute to the balance that determines pH, including the many dissolved minerals that give sea water its “saltiness.” Water flowing from the land carries these materials into the ocean, tending to maintain pH within a constant range. The changes shown in the diagram above are a perturbation from this state. Thus, the pH is not a function of the static CO2 concentration in the atmosphere, but rather the change of that level. Atmospheric concentrations of even thousands of ppm will not produce this change under stable, equilibrium conditions; it is normally “buffered” and pH is stable.
That is, unless this buffer is overwhelmed. A rapid addition of CO2 to the ocean can exceed the flows of additional minerals from the land, overwhelming the buffer. Secondly, if CO2 levels change rapidly — faster than the “overturning” mixing time for the entire ocean — these chemical changes become restricted to the upper ocean. The deep ocean isn't involved; there isn't time. It is as if the ocean were very much smaller.
So, changing CO2 concentrations on timescales of millennia is slow enough to not cause these problems, thus the changes in CO2 concentrations we see over the glacial cycles, over many thousands of years, don't cause a problem. When the same changes occur over decades, this overwhelms the system and perturbation occurs. Ocean acidification is a speed problem!
A reduction in the concentration of carbonate in the ocean causes problems for solubility of calcium carbonate. With high carbonate concentrations, calcium carbonate can precipitate out of the water and form limestone. Whereas if the carbonate concentrations are too low, limestone will actually start to dissolve. The key measure of this saturation state is given by the value Ω, a function of the reaction rates for the various components. When Ω is above 1, the water is “saturated” and carbonate deposition is possible; below 1 and it is under-saturated and dissolution occurs.
This is shown clearly by the natural variation of pH in the ocean. Upper waters have a higher pH and are typically saturated. The deep ocean, in contrast, has a lower pH and is under-saturated. The transition depth is called the carbonate compensation depth (CCD). The following graphs show the average state of Ω in the Pacific and Atlantic oceans. They are shown for the two common forms of calcium carbonate, calcite and aragonite. They have somewhat different Ω values for the same water conditions due to their different crystal structures. The CCD is where the dashed line intersects the curves. As a result, in the deep ocean all the rocks are dark. Carbonate rocks such as limestone struggle to exist — they dissolve.
Because of the perturbation due to the rapid increase in CO2 concentrations, surface waters are going to shift to the left on these graphs.
Why does this matter? Because many marine creatures use calcium carbonate in forming their shells. So a low Ω impacts their shell-forming capacities, which may be life and death for them. This includes not only oysters, mussels, etc., but also many corals and many microscopic creatures such as coccolithophores and pteropods at the base of the ocean food chain. Oyster farmers along the North American Pacific coast have seen what this can do. Strong off-shore winds drive surface waters away from the coast and draw deeper water up, with a lower Ω. Mass die-offs of oyster larvae have occurred. Farmers can compensate for this in their breeding tanks — not so out in the wild. Similarly, degradation of the shells of pteropods — tiny, free-swimming marine snails — is already being observed in the Southern Ocean.
And this has happened in the past. When CO2 levels have changed sharply, ocean acidification events have occurred before and left their mark on marine life, a mark stored in the fossil record.
CO2 is “plant food,” so everything is good, right? No!
A recurring theme in Professor Happer's arguments is expressed in the rather simplistic thought, “CO2 is plant food,” which shows an extraordinary lack of knowledge of botany, perhaps understandable since his field is optics. Overwhelmingly, what is missing from his discussion is temperature. Going through some points:
He showed photographs of plants grown in elevated CO2 environments in laboratories. It is difficult to draw conclusions from experiments such as this because other factors are not included. Yes, plants may well grow like that in artificial environments. Studies from free-air CO2-enriched (FACE) studies, where CO2 is added to the atmosphere in natural growing conditions, show more muted results.
The Professor displayed a map from a study by Donohue et al., 2013 [Happer Statement; Figure 17 — eds.], showing increased vegetation coverage, and his text suggests a “greening of the Earth” and increased crop yields, all as a result of CO2 rises. The cited paper includes the graph below: expected increase in percent foliage cover due to increased CO2 (the marked area in the lower graph) vs. annual rainfall. This graph shows a quite marked increase where rainfall is less than one meter per year, but relatively small in higher-rainfall zones.
The Donohue et al. paper is also far more reserved in its statements:
While a land-based carbon sink has been observed (Ballantyne et al., 2012; Canadell et al., 2007) and satellites reveal long-term, global greening trends (Beck et al., 2011; Fensholt et al., 2012; Nemani et al., 2003), it has proven difficult to isolate the direct biochemical role of Ca ["atmospheric carbon" — eds.] in these trends from variations in other key resources (such as light, water, nutrients [Field et al., 1992]) and from socioeconomic factors such as land use change (Houghton, 2003) (my emphasis). . . .
The results reported here for warm, arid regions do not simply translate to other environments where alternative resource limitations (e.g., light, nutrients, temperature) might dominate, although the underlying theory remains valid (my emphasis).
Many of the regions showing greening on the map are not warm and arid environments. Professor Happer seems to be seriously exaggerating the results from this study. And his claim of expected greater crop yields is not even discussed.
The Professor's discussion of photosynthesis describes the diffusion of water vapor out of the stomata of leaves and the relationship to CO2 diffusing in, as well as the fact that higher CO2 levels mean less consumption of water by the plant, a useful benefit in arid climates. But he omits a key earlier process. Water exists within a plant's tissues as a liquid, and to be present within the stomata as water vapor, it first must be evaporated from the plant. Evaporation cools the plant's leaves. This is the second key role that water plays for a plant: cooling. Less water consumption is not always positive, as it may also impair the plant's cooling mechanism.
Temperature — specifically leaf temperature — is a critical factor in photosynthesis and crop yields. Photosynthesis is temperature-dependent: the productivity of photosynthesis is poor at low temperatures, rising to a peak around 30° C for C3 photosynthesizers, slightly higher for C4 plants. Beyond this peak, photosynthesis efficiency declines markedly, dropping to very low by around 40° C. At these temperatures, plants have typically switched to photo-respiration, burning sugars with oxygen and producing CO2. Above 40° C, RuBisCO, the key enzyme in photosynthesis, starts to break down. The plant needs to regenerate more to restore previous photosynthesis rates. Importantly, it is the leaf temperature that governs this, not the external air temperature. Changes in water transport in plants can directly impact this because with less evaporative cooling, leaf temperature is not as well insulated from air temperature changes.
This relationship between photosynthesis and temperature shows up markedly in crop yields in different climates: most regions grow the crops most suited to their climate. The following graph highlights how crop yields vary with temperature (in degrees F) for different crops, relative to the maximum possible yield at their optimum. Note the steepness of the drop-off for rice yields in India (Kolkata). Rice is being grown near its maximum temperature range in many parts of the tropics.
Now, doubling CO2, and adding temperature increases, as well:
Increases in crop yields occur in more temperate climates, but major declines in rice yield occur in India. This is a major pattern in the response of crops to combined CO2 and temperature increases. Improved yields at higher, cooler latitudes but yield declines in low, equatorial latitudes — where some of the largest human populations are. This will constitute a major shift in agricultural productivity from the poorer, warmer, more-populous regions, to the already-prosperous, cooler, less-populous regions. One wonders what sort of social, economic, and military implications are hidden within such a simple graph.
A recent study by the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia highlights this. Crop yields in Australia's wheat-growing regions roughly tripled between 1900 and 1990. Since then, they have essentially flat-lined. Australian wheat farmers have been using ever-better farming practices to increase the percentage of the potential yield of their farms. Potential yield is the theoretical maximum yield a field can produce given soil type, climate, crop type, etc., under ideal conditions. Farmers aim to improve the percentage of this optimal yield that is actually achievable, and Australian wheat farmers have been doing that. But at the same time, the potential yield of their fields has been dropping for a quarter of a century, due to climate changes.
Potential yield in wheat declined by 27% over 25 years. 83% of this was due to reduced rainfall, 17% due to rising temperatures. Whereas if CO2 levels hadn't risen over that period, potential yield would have dropped another 4%.
Extra CO2 helped, but it could only partly compensate for the other climatic changes. Which is the flaw in Professor Happer's argument. He assumes CO2 rises while no other consequences occur. But there are other consequences and the “plant food” aspect is dwarfed by temperature, water, and other climate factors. He is only looking at one piece of a much bigger puzzle.
The next potential impact of reduced water usage/uptake by plants is fewer minerals. Plants only obtain carbon and oxygen from the atmosphere (and nitrogen-fixing plants also obtain nitrogen); all the other minerals are drawn up from the soil, dissolved in the water from their roots. If a plant is using less water, it is drawing up fewer minerals. Some of these are needed by the plant, others may be incidental. Predators that eat the plant, such as cows or humans, need minerals that the plant does not: iron for oxygen transport, calcium for bones, potassium for propagating nerve signals in brains. The diversity of mineral needs for plants and animals, and people, comes from the volume of water the plant takes in. And, unsurprisingly, studies of crops are starting to report declines in mineral content.
Here are some unexpected consequences (at least to non-botanists):
- Protein-to-carbohydrate ratios in crops may change. There is not much point in even just maintaining yields, if we need to eat more to get the same amount of protein. This is being reported for some crops.
- Toxin levels can change. A plant may devote more resources to defense, and produce more toxins to ward off predators. Our morning cup of coffee highlights this. Arabica strains of coffee trees grow at higher, cooler altitudes, are used in premium coffee, and are lower in caffeine, the trees' pest deterrent. Robusta coffee trees grow at lower, warmer altitudes, are higher in caffeine, and are only used for instant coffee.
- Pests travel farther and disrupt things.
- Pollinators don't align their breeding cycles with the plants.
Looking at the aggregate, the graph below presents a summation of conclusions. This graph (from the most recent IPCC report) is a synthesis of what the agricultural science community thinks will happen to crop yields through this century, considering a range of factors.
The graph shows roughly equal numbers of predictions for increases and declines in yields early in the century, but by century's end, predictions are predominantly for yield declines. That yield declines of 50%–100% are even on the graph by century's end, let alone in nearly 20% of studies, is truly sobering.
A critical point that Professor Happer totally ignores is the speed of the current changes. The rate of rise in CO2 levels today is unprecedented in at least the last 55 million years.
If we look at more recent data — the ice core records that span back hundreds of thousands of years — we see CO2 concentrations varying by around 100 parts per million (ppm) over time scales of tens of thousands of years. The most rapid changes are typically during the great deglaciations, when levels rise by 100 ppm in around 10,000 years: 1 ppm per century.
Today, CO2 levels are rising at 1 ppm every 22 weeks!
If we go back 55 million years, to the boundary between the Paleocene and Eocene periods, a rapid CO2 level rise occurred and a sharp warming event happened, called the Paleocene/Eocene Thermal Maximum (PETM). Temperatures spiked by perhaps 6° C and a small-scale mass extinction event occurred. Studies of sediment cores from that period, taken from the Svalbard islands, show that CO2 levels today are rising 10 times faster than during the PETM.
The only events in geological history where CO2 levels changed as fast or faster than today were during the greatest mass extinction events. For example, take the End-Permian Mass Extinction 252 million years ago, where 75% of families of species of plants and animals on land went extinct; in the oceans it was 96%.
Speed matters because this governs the capacity of ecosystems and species to adapt. And our farms are also ecosystems.
Deep Time and CO2
Professor Happer opened his argument with a graph of CO2 concentrations over deep time (Statement, Figure 1), and said:
The mean global temperature was sometimes higher and sometimes lower than today's. But the temperature did not correlate very well with CO2 levels. For example, there were ice ages in the Ordovician, some 450 million years ago, when the CO2 levels were several thousand ppm.
But temperature does correlate quite well when we combine together the forcing impact of CO2, which varies logarithmically with its concentration, and the long-term changing heat output from the Sun.
Lest we wonder how the Ordovician ice age could have occurred (at the end of the “O” in the above diagram), GEOCARB III (which Professor Happer also references) is a geochemical model, which estimates past CO2 levels from the chemistry of rocks. Its calculations are run over steps of 10 million years and averaged over 50 million years. It is not sensitive enough to detect shorter-term changes. Direct geological evidence shows that CO2 levels fell sharply during that period, in 1 to 2 million years or less — too small for GEOCARB III to capture. A higher-resolution geochemical model applied just to this period suggests a decline of CO2 levels from ~5000 to 3000 ppm. With differences in solar output, 3000 ppm then is equal to 500 ppm today. Climate models applied to late Ordovician conditions predict icehouse conditions at CO2 levels below about 2240 to 3920 ppm.
The explanation is that changes in the greenhouse effect over time, due to changes primarily in CO2 and methane levels, explain much of the observed climate history. They aren't the only factors. Orbital cycles influence how much sunlight the Earth receives. The extent of snow and ice changes how reflective the Earth is. The position of the continents matters (land reflects more sunlight than the oceans), and continents shape the flow of ocean currents, influencing heat transport. For around 30 million years, Antarctica has been isolated and surrounded by a huge current, the Antarctic Circumpolar Current, promoting cooling. For many, hundrreds of millions of years before, this wasn't so.
But greenhouse gases are one of the few factors that can change independently and quickly, whether from huge volcanic events, or our massive release of sequestered carbon from fossil fuels. Most other factors are slow or are feedbacks.
- We know the science of the greenhouse effect, including the role of CO2, even as vast as the GH effect on Venus.
- We see the actions of the major climate feedbacks — such as water vapor feedback and retreating ice and snow changing reflectivity — happening around us.
- Most of the science strongly suggests the climate sensitivity is centered at a value of around 3.
- The Earth's deep past agrees with this central estimate.
- The deep past also tells us that climate can vary wildly and dangerously, from deadly hothouse, through benign climates, to frozen snowballs. There in no reason to think such changes are not possible again, if we prod the system hard enough.
- We are changing the system at extraordinary speed, compounding any problems.
- Sea-level rises that will disrupt societies for centuries are now locked in.
- Changing climate disrupts ecosystems and crop systems. It changes how much food can be grown where. And this most-adversely impacts the poorest and most-populous countries and those dependent on the oceans.
- With our current population, we depend on a functioning ecosystem for the entire planet to support ourselves.
- These changes will stress societies, security, and human mental and emotional health.
- And there are other impacts not even discussed here . . . .
How could the application of “alternative facts,” selective evidence, blinkered logic, or any form of motivated reasoning turn this into something where the description “good” could ever be applied? This is not good!
Afterword: A Note on Tone
Professor Happer's Statement is peppered with highly emotive language, for example:
- “alarmists,” “extremists”
- “Some people claim that fossil fuels are inherently evil.”
- “Orwellian Newspeak”
- “There is nothing to insure against, except the threats of an increasingly totalitarian coalition of politicians, government bureaucrats, crony capitalists, thuggish nongovernmental organizations like Greenpeace, etc.”
- “To cope with this threat to full employment, the climate establishment has invented a host of bogeymen, other supposed threats from more CO2.”
- “The climate-alarm establishment has largely dropped the term ‘global warming' and replaced it by the much more flexible phrase ‘climate change.' The unspoken and assiduously promoted assumption is . . .”
- “ . . . how it was possible for a seemingly enlightened civilization of the early twenty-first century to demonize CO2, much as the most ‘Godly' members of society executed unfortunate ‘witches' in earlier centuries.”
- “The global warming crusade”
If professor Happer wishes to convince anyone of the merit of his argument, for which he offers little evidence, this tirade would seem to be a profound black mark against that. Does he have so little to say that he needs to resort to emotive invective and ad hominem attacks? Has he no better argument? Is this the best he can do?
Sources and References
Cook, John, et al., “Quantifying the consensus on anthropogenic global warming in the scientific literature,” Environmental Research Letters, 2013, 8: 031003.
Krivova, N.A., L. Balmaceda, and S.K. Solanki, “Reconstruction of solar total irradiance since 1700 from the surface magnetic flux,” Astronomy and Astrophysics, 2007, 467: 335–346.
Lacis, Andrew A., et al., “Atmospheric CO2: Principal Control Knob Governing Earth's Temperature,” Science, 2010, 330: 356–359.
Soden, Brian J., et al., “Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor,” Science, 2002, 296: 727–730 (DOI: 10.1126/science.296.5568.727).
Working Group 1 (WG1), Fifth Assessment Report (AR5), “Climate Change 2013: The Physical Science Basis; Technical Summary” (Intergovernmental Panel on Climate Change [IPCC], 2013).
Working Group 1 (WG1), Fifth Assessment Report (AR5), “Climate Change 2013: The Physical Science Basis; Chapter 9. Evaluation of Climate Models” (Intergovernmental Panel on Climate Change [IPCC], 2013).
Working Group 1 (WG1), Fifth Assessment Report (AR5), “Climate Change 2013: The Physical Science Basis; Chapter 10. Detection and Attribution of Climate Change: from Global to Regional” (Intergovernmental Panel on Climate Change [IPCC], 2013).
PALAEOSENS Project Members, “Making sense of palaeoclimate sensitivity,” Nature, 2012, 491: 683–691 (DOI: 10.1038/nature11574).
National Snow and Ice Data Center (NSIDC) (Consortium consisting of University of Colorado-Boulder, Cooperative Institute for Research in Environmental Sciences [CIRES], National Aeronautics and Space Administration [NASA], National Oceanic and Atmospheric Administration [NOAA], and National Science Foundation [NSF], 2017).
Banwell, Allison F., et al., “Breakup of the Larsen B Ice Shelf triggered by chain reaction drainage of supraglacial lakes,” Geophysical Research Letters, 2013, 40: 5872–5876 (DOI: 10.1002/2013GL057694).
DeConto, Roberto M. and David Pollard, “Contribution of Antarctica to past and future sea-level rise,” Nature, 2016, 531: 591–597 (DOI: 10.1038/nature17145).
Hansen, James, et al., “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2° C global warming could be dangerous” Atmospheric Chemistry and Physics, 2016, 16: 3761–3812.
Greenbaum, J.S., et al., “Ocean access to a cavity beneath Totten Glacier in East Antarctica,” Nature Geoscience, 2015, 8: 294–298 (DOI: 10.1038/ngeo2388).
Heinrich, Paul V., “Antarctic Bedrock” (Wikimedia Commons, 2008). This map was prepared by Dr. Heinrich from a BEDMAP gridded data set for bed elevation south of 60 degrees S using Global Mapper 7.0.1. The faint rectilinear pattern seen in the shaded relief is an artifact of the gridding of data from linear seismic surveys. The data used to make this map came from Matthew B. Lythe, David C. Vaughan, and the BEDMAP Consortium, “BEDMAP: A new ice thickness and subglacial topographic model of Antarctica,” Journal of Geophysical Research, 2001, 106: 11335–11351. The BEDMAP Consortium is sponsored by the European Ice Sheet Modelling Initiative (EISMINT) and the Scientific Committee on Antarctic Research (SCAR).
O'Leary, Michael J., et al., “Ice sheet collapse following a prolonged period of stable sea level during the last interglacial,” Nature Geoscience, 2013, 6: 796–800 (DOI: 10.1038/ngeo1890).
Cornell, Sean, et al., “Coastal Processes, Hazards, and Society: Sea Level Change During the Last 5 Million Years” (College of Earth and Mineral Sciences, Penn State University, 2016).
“Ocean Acidification: The Chemistry of Ocean Acidification” (Woods Hole Oceanographic Institute, 2012).
“World Ocean Circulation Experiment (WOCE), 1990–2002” (National Oceanic and Atmospheric Administration [NOAA], 2013).
Bednaršek, N., et al., “Extensive dissolution of live pteropods in the Southern Ocean,” Nature Geoscience, 2012, 5: 881–885 (DOI: 10.1038/ngeo1635).
Donohue, Randall J., et al., “Impact of CO2 fertilization on maximum foliage cover across the globe's warm, arid environments,” Geophysical Research Letters, 2013, 40: 3031–3035 (DOI: 40: 3031–3035).
Hatfield, J.L., et al., “Climate Impacts on Agriculture: Implications for Crop Production,” Agronomy Journal, 2010, 103: 351–370 (DOI: 10.2134/agronj2010.0303).
Hochman, Zvi, et al., “Climate trends account for stalled wheat yields in Australia since 1990,” Global Change Biology, 2017, 23: 2071–2081 (DOI: 10.1111/gcb.13604).
“Changing climate has stalled Australian wheat yields: study” (The Conversation, 2017).
Myers, Samuel S., et al., “Increasing CO2 threatens human nutrition,” Nature, 2014, 510: 139–-142 (DOI: 10.1038/nature13179).
Weigel, Hans-Joachim, “Crops and Climate Change: Plant quality declines as CO2 levels rise,” eLife, May 2014, 3: e03233 (DOI: 10.7554/eLife.03233).
Working Group II (WG2), Fifth Assessment Report (AR5), “Climate Change 2014: Impacts, Adaptation, and Vulnerability; Summary for Policymakers (SPM),” Figure SPM.7 (Intergovernmental Panel on Climate Change [IPCC], 2014).
Ibid.; Figure SPM.5.
Royer, Dana L., “CO2-forced climate thresholds during the Phanerozoic,” Geochimica et Cosmochimica Acta, 2006, 70: 5665–5675.