I would like to thank Professor Happer for his Response to Dr. Karoly’s earlier Statement and Interview. I would also note that Professor Happer is in a somewhat awkward position, responding to two different parties as a result of Dr. Karoly’s withdrawal from this Dialogue.
That said, I have to disagree with the Professor — he has not made his case, and here is why.
The crux of this conversation is a simple question:
Will human activity — primarily, but not only, our burning of fossil fuels — produce changes to the world’s climate system that may be harmful to human society and the natural world, to a sufficiently large degree to warrant significant responses, and possibly even changes in how our economies function?
There are also several subordinate questions that I will consider in this Reply:
- Can adding carbon dioxide (CO2) and other greenhouse gases have some climatic influence? Yes. Professor Happer and I agree on this point, so no further discussion is warranted.
- Will such changes to the climate be significant in nature, as encapsulated in the concept of “Climate Sensitivity” (CS)? We disagree. The Professor believes CS is low, while I contend, based on the evidence, that it is significantly higher.
- Will changes to climate have negative impacts on human society or the natural world? I say yes, and there may be additional, non-climate reasons why impacts are significant.
- Are there any positive consequences that might outweigh any negative impacts? I contend that the negatives substantially outweigh the positives.
- Do these impacts warrant a response? This depends on what response is needed, and any impact that this in turn may have, and also on how we apply risk-assessment principles to evaluate this.
Too Much Rhetoric
Much of Professor Happer’s Response to Dr. Karoly does not discuss these five questions. His response contains little discussion of science, evidence, or the physical principles of the climate system. In a guided tour, Professor Happer displays his knowledge of history and literature. He makes statements that might well have relevance if his views are correct. However, these comments contribute little to demonstrating that his views actually are correct.
Most of the Professor’s Response is rhetoric, not logic. The ancient Greeks esteemed rhetoric as one of the key tools of an orator. The difference between the use of logic and rhetoric can perhaps best be summarized as:
Logic convinces, rhetoric sways.
However, no amount of rhetoric prevents a Marine-Terminating Ice Sheet from melting when the ocean around it is too warm. Physics ignores emotions or emotional language as Professor Happer, a Professor of Physics, presumably understands.
The Professor’s Response suggests that he thinks he is right, that all others’ views must be based on more emotional motivations, and thus that he should respond in kind. Queue phrases such as “climate establishment,” “another international crusade,” “this modern crusade,” “Gordian knot of jargon, models, confessions of faith,” “climate-science establishment,” “alarmist,” etc., etc.
Not much evidence in any of this. If, however, the Professor is wrong, then most of his Response is an emotive distraction. So, we need to consider whether the evidence supports Professor Happer’s view: this discussion hinges on that. Then, we can all read about the Council of Clermont at our leisure.
Firstly, to what Professor Happer has said in his Response.
He has elaborated further on ocean pH, again failing to understand that the problem is the biogeochemistry of the oceans and carbonate under-saturation, as discussed in my previous Response. Marine life is already showing the first impacts of ocean acidification on their shells.
Regarding more extreme weather events, rather than presenting cherry-picked data from small regions or single types of events — which isn’t very informative — the IPCC has assessed the whole world:
Or we can use data from reinsurance companies, such as Munich Re, who “insure the insurers.” They collect global data on insurable natural disaster events. They find that climate-related events are rising, while geological events such as earthquakes are steady. Importantly, their data consist of number of events, not cost of damages, so confounding factors such as economic and population growth are not an issue.
As noted in my Response, Northern Hemisphere snow and sea ice cover is declining. This is a positive albedo feedback already, absorbing more sunlight. The changes to date have added the equivalent of 25% more radiative forcing than CO2 alone.
The Temperature Record
The Professor commented on the slight cooling in the surface temperature record between the 1940s and 1970s. However, he seems unaware that the surface record has a well-known spurious warm bias due to a marked change in measurement techniques during the war years and, to a lesser extent, the 1960s. 
Also, he doesn’t mention that the 1950s to 1970s were the peak years for air pollution, which has a cooling effect. The Professor’s comment about whether there are enough surface measurement sites to give adequate sampling reveals he does not understand the difference between measuring weather vs. climate. I present a detailed discussion of the principles of surface temperature measurement that he may find enlightening.
Measuring atmospheric temperatures by satellite is difficult: orbital drifts by each satellite; signals that arise from multiple levels in the atmosphere with differing warming and cooling rates; and other factors must be taken into consideration. In his Interview, the Professor claimed, regarding the data shown in his Response, Figure 5:
The data came from NOAA’s TIROS-N satellite . . .
This is totally wrong! TIROS-N was launched in 1978 and only operated for 868 days. The satellite data-set he refers to uses data from 13 different satellites over multiple decades. The Professor needs to get his facts straight.
Stitching together raw data from multiple satellites is very complex. Thus, the satellite data-sets are much less accurate than the surface temperature data-sets.
Professor Happer’s stronger emphasis on satellite temperature measurements does not agree with the experts on the subject. More generally, a range of measurements all show a warming world:
The Professor appears to think CO2 is the only factor influencing climate; thus, if climate does not respond to CO2 levels alone, this is evidence against the role of CO2. In fact, climate responds to several factors, greenhouse gases (not just CO2) being important, but not the only one. His argument is an example of the “fallacy of the single cause.”
The “Earth” Isn’t Just the Atmosphere
A repeated mistake Professor Happer makes is referring to surface and atmospheric data as “the Earth,” when thermodynamically this is a small part of the system. Most of the changes in heat content — over 90% — are in the oceans and thus are the primary measure of whether the Earth is warming or cooling. Modest changes in the patterns of heat exchange between the oceans and the atmosphere can cause atmospheric climate to vary significantly. This is why atmospheric climate is so variable, and thus why we need 30+ years to distinguish it from weather. The atmosphere is the tail wagged by the dog of the oceans.
If we only relied upon atmospheric data, we would be more circumspect in our conclusions since it such a small part of the system, thermodynamically. But we are also monitoring the oceans, and they tell the tale: the Earth is clearly warming, with no pause. So the Professor’s reference to the period labeled “the Little Ice Age” is again missing the point; this is still only the atmospheric climate.
Climate Sensitivity isn’t low
The Professor’s view that climate sensitivity (CS) is quite low seems to derive from not understanding the water vapor feedback. As I discussed in my Response, this is a routinely observed feedback, part of normal meteorology. And satellite measurements observe a rising trend, a feedback.
The Deep Past: A Climate Roller Coaster
As I discussed previously, the estimates of CS by the scientific community agree with the picture of climate from the Earth’s deep past. The climate on Earth has varied over a large range; at times it has been much hotter than it is today, at time much colder. During the reign of the dinosaurs, there was likely no permanent ice cover. During the most extreme warm event of the last 500 million years, the end-Permian Mass Extinction Event of 252 million years ago, upper ocean temperatures may have reached 35–40 °C, while temperatures in the tropics would have been lethal for humans.
Seventy-five percent of families of species of plants and animals on land went extinct, 96% in the oceans. Massive erosion followed, since the worlds forests were decimated — so much so that no new coal was laid down for 10 million years after the event: the so-called “Coal Gap.” Our civilization would not survive on a world like this.
At times, the Earth has also been covered substantially — perhaps pole to pole — by ice: a “Snowball Earth.” This has occurred several times; an entire geological period, the Cryogenian of 720 to 635 million years ago, gets its name from this. How could the planet have become so cold? Since the greenhouse effect warms the Earth by over 30 °C — not 9 °C, as the Professor wrongly calculated — a weakening of of the greenhouse effect offers huge scope for cooling. With a cooler Sun in the deep past, if greenhouse gas concentrations fell significantly, a temperature drop causing massive glaciation could easily occur.
Once largely covered with reflective ice, how would the Earth ever thaw again? CO2 is continuously being drawn from the atmosphere, dissolved in raindrops, and ending on the sea floor as limestone (this is a very simplified description). In a frigid world with little rainfall this flow would shut down, while volcanoes would keep slowly adding CO2, with the result that concentrations would steadily rise and rise. Eventually, a stronger greenhouse effect, possibly coupled with extra methane and other greenhouse gases and other factors, could warm the Earth and start melting the ice, exposing dark rock and ocean, and thus rapidly escalating the melt, leaving a huge greenhouse effect and a much warmer world. Rainfall would resume massively, restarting the CO2-to-limestone pump, depositing carbon as massive beds of carbonate rocks, and lowering atmospheric CO2 and temperatures again. All in all, a wild climate roller coaster driven by fluctuations in the greenhouse effect.
This is what the geology of a Snowball Earth event actually looks like:
The lower layers are sediments and embedded “dropstones” dropped to the sea floor from ice floating above. Then a sharp boundary to a thick layer above of “cap carbonate” rocks — a massive and quite rapid draw-down of atmospheric CO2, now deposited as carbonate. First, there is the signature of a frozen world with too little greenhouse gases; then, above, there is the carbon that helped warm the world via a huge greenhouse effect. All recorded in the rocks.
Not all the science of these events is understood, but the salient point is that they occurred. The point to this history tour is simple: I climate sensitivity is low, how do we explain such a highly variable climate? A climate system with a significant CS and a significantly changing greenhouse effect explains much of what we see. CO2 has been called the “main control knob” for the climate, and for good reason. The Professor’s personal view of a low CS, unsupported by any evidence from him, does not match the observations. His argument that negative impacts cannot occur also fails; they have happened repeatedly.
A recent study has highlighted just how profound the burning of fossil fuels could be. If we burn all the available fossil fuel reserves — a logical outcome of the Professor’s view — we would create a situation unprecedented in the last 500 millions years.
A business-as-usual emissions scenario, defined by the IPCC (RPC8.5), would take us into a hothouse climate last seen by the dinosaurs. Burning all the available fossil fuels (Wink12K, above) would push us to a state perhaps exceeding the End-Permian Mass Extinction event — and, as I described previously, at a geologically extraordinary speed.
The first reports of major coral bleaching appeared in 1980; prior to that it was essentially unknown. Cores drilled from 400-year-old corals have not shown bleaching events in the past and other studies show no bleaching looking back thousands of years. Coral bleaches when water temperatures are too high; they eject their zooxanthellae symbionts (a member of the phylum Dinoflagellata). Deprived of the carbohydrates and oxygen these single-celled, photosynthetic, planktonic microorganisms produce, the coral polyps struggle and can die. A bleached reef may take a decade or more to recover from a bleaching event, if coral mortality is not too high. If bleaching becomes more frequent than that, they can’t recover.
Bleaching events have been occurring around the world continually for several years, beginning in Guam in June, 2014.
The Great Barrier Reef has experienced large-scale bleaching two years in a row.
Coral bleaching is not a future impact. It is here now. Coral reefs are not just beautiful, they are protective storm barriers and huge sources of tourism revenues. They are relied upon by 25% of all marine species, particularly as a nursery for juvenile fish before they venture out to the open ocean. About 500 million people globally depend on fisheries from coral reefs for food.
The Arctic Sea Ice is Vanishing
Arctic sea ice is vanishing. In a steady, perhaps increasing, trend, the amount of sea ice in the Arctic ocean is declining. At the end of the melt season each September, the volume of the sea ice has declined by around 75%. This year, the volume of ice at the end of the freezing season is at a record low, perhaps priming a record low volume in September.
The area of the ice has shrunk, but it is also thinner. Most of the thick, multi-year ice is gone, replaced by ice only 1–2 seasons old. The structural integrity of the ice pack is reduced — images from satellites show a far more broken-up ice pack. Cracks are spreading farther and the ice is more mobile.
The long-term trajectory is clear: an essentially ice-free Arctic in summer within some years or, at most, decades.
Loss of Arctic sea ice will hurt species like ring seals, polar bears, walruses, etc., which need the ice to live and breed. It is also providing an increased range for whales. However, the bigger potential impact of changing sea ice is the impact on weather systems. Open water during the northern summer means the Arctic ocean warms more, impeding the fall refreeze. Increased evaporation starts to add more water vapor to the Arctic weather systems, increasing the greenhouse effect locally. All of this contributes to disrupting circulation patterns and global heat flows.
The Polar Jet is Changing
The northern polar jet stream occurs at the boundary between the polar and temperate climate bands. Meandering around the high northern hemisphere, it separates Arctic from temperate weather patterns. When the jet dips south, the weather north of it is colder and, in winter, snowy, fed from the Arctic. When the jet veers north, regions south of it are more temperate, or, in summer, hot. The alternation between the two patterns is important. If the jet stops moving, it “blocks,” and local weather can become more intense: longer and worse heat waves or longer and worse blizzards. At present, the polar jet is doing exactly that: slowing, meandering more, passing more slowly over regions, and blocking more.
In 2010, the polar jet blocked in place over western Russia for an extended period. Hot, dry air from the Mediterranean produced one of the worst heat waves on record in western Russia and massive forest fires.
It was less well reported that it also devastated the Russian wheat harvest. Russia suspended wheat exports that year and global wheat prices spiked higher. High wheat prices and bread shortages have been identified as one of the triggers for the Arab Spring. That same year, the same weather patterns produced massive flooding, devastating Pakistan and killing nearly 2000 people.
As global weather systems reconfigure, we may expect to see changing local weather patterns. Some heat waves and storms may individually be worse. What is often not recognized is the disruption that can be caused simply through changing local conditions. Our infrastructure is engineered for the local weather: heat or cold, amount of rainfall or snow, frequency of floods, etc. As I discussed previously, our agriculture is geared around particular local climates. We build cities near the coast, assuming they won’t be inundated by the sea.
We can live in many parts of the world, if the local conditions are predictable. Climate change potentially disrupts predictability. The consequences are human, and we react, but not always peacefully. Refugees, economic costs, political turmoil, tensions between nations and ethnic groups — all can flow as consequences of the failure of this predictability.
In Bangladesh, sea level rise is expected to cause several million internal refugees to move to the cities. In Syria, 1.5 million people moved to the cities due to prolonged drought, a factor in the current terrible strife there, which then turned into a refugee crisis in Europe and triggered political discord on that continent. In other words, climate change is not just about the climate: it has economic, political, and potentially military consequences, as well. In the most recent Quadrennial Defense Review, the U.S. Defense Department identifies climate change as one of the major security issues of the twenty-first century — one of the significant “threat multipliers” that they foresee.
Are there any positives?
As I outlined previously, crop yields depend strongly on average temperature, and yields in higher latitude countries may well increase, a local benefit for those regions. A warmer world may well mean that high latitude and polar regions will have milder winters and fewer winter deaths, a likely benefit.
But it is hard to see many other benefits. In the low latitudes, crop yields will likely decline and deaths due to heat waves increase. We can protect against cold, but when outdoor temperatures become too hot, all we can do is shelter indoors in our air-conditioning — for those that have it — disrupting work and production, and stressing crops and animals. This is where most of the world’s population lives: the tropical and lower-latitude temperate regions. A warming, changing climate will disrupt the current balance between where most people live, and how easy or possible it is to live there, creating a serious maldistribution of costs and benefits. The military are right to see major security threats in the consequences of this: disruption is dangerous.
So, rising seas, shifting weather patterns, bleaching reefs and ocean acidification, shifting agriculture, a rising maldistribution of resources and needs, all in a climate of rising uncertainty, fear, and doubt about the future. Add to this the long history of the Earth’s telling us very clearly that this, and much, much more, is all too possible. Do you think, on balance, that all of this will have positive impacts? I don’t.
Risk and action
So, does all this justify action? Firstly, we need to consider risk. The range of possible climate sensitivities, while centering around 3, does include lower and higher possibilities. While lower outcomes obviously would be preferable, good risk management requires that we give a weighting to lower-probability but high-severity possibilities.
This necessity is compounded by the fact that the climate system has high inertia: it takes time for all the consequences of our emission of greenhouse gases to play out. Sea level rise will continue for many centuries, and even shorter-term impacts can still take decades to manifest. Added to this, a significant portion of the gases we add to the atmosphere will remain there for centuries, even millennia. We are locking in a very long-term change, while lacking certainty about its eventual severity. Barring some extraordinary geo-engineering to remove those gases from the atmosphere, we are committing our descendants to an uncertain, and possibly very harsh, future.
The precautionary principle is part of our legal system. Once the possibility of a risk has been identified, we are required to demonstrate that a course of action is safe. For example, it is part of U.S. Department of Labor Occupational Health & Safety Administration law. To continue with an action, we must demonstrate safety, not risk.
So, by the standard of “beyond a reasonable doubt,” is continuing to release greenhouse gases safe? I believe I have shown that it is not safe. Professor Happer, on the other hand, has failed to demonstrate that such a course of action is safe; he seemingly only presumes it is. That is hardly sufficient grounds for risking much human suffering.
However, to cease our emissions of greenhouse gases, we must take various actions. Are these in turn safe? Primarily, we would need to switch to non-emitting technologies (of CO2, methane and nitrous oxide) for generating electricity, powering transport, providing heating and cooling, managing how agriculture is done, and making cement and steel. Concern has been expressed in the past that this would be too expensive and the main types of new energy technologies are unreliable or inadequate. Thus, there could be significant economic harm in making the switch. If the proposed solutions really were detrimental, then we would face a harsh dilemma: the risk of future serious harm, or the pain in trying to prevent it.
However, this situation is changing rapidly. Major advances in technologies and their costs — renewable power, energy storage, electric vehicles, etc. — are transforming this balance from expensive and unreliable to mature, low cost, and safe.
For example, Abu Dhabi recently signed a power purchase agreement for a 1.17 GW solar photovoltaic (PV) “farm” that will supply electricity at 2.42 U.S. cents/kWhr — just about the lowest wholesale electricity cost anywhere in the world. We are on-track to having 3 terawatts (TW) of renewable electricity-generating capacity by 2030 and 10 TW, if impediments can be removed. Total world electricity generation is currently 6 TW. A series of industrial revolutions is occurring that is changing the balance between the risks of inaction vs. action, rendering any previous arguments against action out of date.
I believe I have made the case that global warming is real, human-caused, and not a good thing, and that action to minimize it is needed, is justified, and is actually the far safer course of action. Professor Happer, in my view, has not made his case.
On the balance of the evidence, the case for human agency as the cause of a changing climate, with real risks to future generations, is strong. This is supported by most of the world’s scientific community, most professional scientific bodies, including around 80 National Academies of Science, and nearly 200 national governments.
Global Warming is not good. Inaction to prevent global warming is not good. Technological progress is rapidly removing any impediments to taking action. What possible reason could remain for not acting?
Professor Happer’s comments also include a range of disturbing suggestions and innuendo such as “If you have the government on your side, why should you worry about getting the science right?,” — a resort to ad hominem as a debating tactic. Yet, the professor has not disclosed all the details about himself in this debate.
For many years, Professor Happer has been associated with the George C. Marshall Institute (GMI), a privately funded, conservative think tank. From 2006, he was employed as the Chairman of GMI. In the past, GMI has taken positions associated with doubting the dangers of passive smoking, the effect of CFCs on the ozone layer, and the risks of acid rain, as well as global warming. In 2015, GMI closed, morphing into the CO2 Coalition, of which the professor is a member of the Board of Directors.
Throughout this Dialogue, Professor Happer has implied various forms of bias and dubious motives on the part of other scientists. He might care to consider whether his own affiliations reflect biases on his part. Professor Happer is a good scientist who means well. But he lives in a small echo-chamber of like-minded people, who are convinced that they are saving the world from new ideas (which they perhaps don’t understand) and defending old, out-of-date verities.
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