Paul Higgins, Ph.D.

Is the science settled, is the Earth, in fact, warming?

We know that the Earth is warming, and we know that because we have multiple, independent lines of evidence that demonstrate that the Earth has been warming. So, we have temperature observations that show warming throughout the world. But, we also have other lines of evidence that show warming as well, independent of those temperature observations. For example, we have melting ice, melting glaciers throughout the world.

We have rising sea levels throughout the world. We have increasing ocean heat content, that is more energy going into the ocean. We see a later onset of winter, and an earlier onset of spring, and we’re seeing biological systems respond throughout the world, and they’re responding with species shifting their ranges, and with species changing the timing of their key life events. And all of those lines of evidence show us that we’re getting warmer, we’re seeing warming throughout the world.

Talk about the glaciers melting.

Well, I suspect what they are rolling their eyes at is this attention that the Himalayan glacier melt story has been getting, and so this is the IPCC’s second working group two discussion. And, in that report there’s a big mistake about the Himalayan glaciers, and the rate that they are disappearing. And, essentially, there’s an error in that report that says they’re going to disappear much more quickly than they, in fact, are.

But, that’s separate from the fact that we know that glaciers are melting throughout the world. So, we know glaciers are melting throughout the world. There was this error, it was a big error, it was an error that shouldn’t have been in there, but it doesn’t take away from that larger conclusion that glaciers are melting throughout the world.

Say it snows unusually in DC, is that reason to question global warming? What does that mean next to the other evidence?

Okay, so you can get events like big snowstorms, you can get particularly cold events in a particular location. That’s not surprising. Weather’s variable. Short-term changes occur. So that’s not a surprise, that we’re seeing things like that, cold spells, heavy snow-snowfalls like the one that DC has been through over this past year. But, there are two things to recognize.

One is that even while you’re having this short-term variability, the weather, that we all know, you’re still seeing changes in the climate system overall. So, we’re still seeing this warming trend overall, even while you have events that don’t necessarily fit your expectations in a warmer world. Now, there’s actually a second piece, which is that as you increase greenhouse gases, you’re increasing the energy at the surface of the earth.

And, so you would expect that you would get larger storms sometimes, because there’s more energy, so you can have more energetic storms. Now, I’m not saying that what we saw over this past winter in Washington, DC was the direct results of human emissions of greenhouse gases, but certainly, you would expect that in a world where we have higher greenhouse gas concentrations, we have more energy in the climate system, and so you’ll have more energetic storms.

Is the idea that CO2 emissions create energy in a system kind of an esoteric idea?

Well, the Earth’s climate system, in many respects, depends on the amount of energy that comes in. So, for example, we get energy from the sun, and that, obviously, is one form of energy that we have to warm the surface and to contribute energy at the surface of the Earth. But, greenhouse gases are another source of energy at the surface of the Earth. So, essentially, the surface emits energy back out to space, but the greenhouse gases absorb it and send it back.

And, that increases the energy at the surface of the earth. When you have more energy at the surface of the Earth, you have things like global warming. But, you also have more energy available for storms, and so this is why we expect that the storm intensity will increase as we have more greenhouse gases.

They’re saying there’s not much consensus within the IPCC.

I’ve never been a big fan of this word, consensus. But what I will say is in the relevant scientific community, the people who study the climate system, there is an overwhelming agreement that climate is changing, and human responsibility for most of the recent changes is well-established. So, that is a widely-held view.

There really isn’t a lot of credible disagreement within the expert scientific community, people who study climate all their lives. So, just some examples of that, you have the IPCC that has essentially said that, you have that further confirmed by the US National Academy of Sciences, which is our leading scientific institution, in my view.

We have 30 other national academies of science throughout the world saying basically the same thing. We also have scientific societies like the American Meteorological Society, like the American Association for the Advancement of Science, the American Physics Society, a whole host of them that have all said that climate is changing, that human responsibility is well-established for that. And I don’t know of any scientific society that actually has a dissenting view on that.

So I don’t like this term, consensus. But, on those conclusions, there is very strong agreement among the expert community.

There are apparently some scientists who are naysayers.

Sure. So yeah, there are a very small number of scientists who are expert in the climate system who have a disagreement with that view. They have developed their arguments, they have presented those arguments, and they have not withstood the vetting of the expert scientific community. There’s not much more you can say.

They have presented those arguments; they haven’t withstood the scrutiny of the expert scientific community. If they had evidence, if they had a counter-view and they could support it with scientific evidence, the climate scientist community would recognize it, take it seriously, and would shift their view to the, based on the evidence. But, their views just haven’t withstood the scrutiny of that expert community.

They’re saying that the complex models that are used are incredibly complex and gives it a false sense of legitimacy, and they have little meaning.

Well, there are a couple of criticisms I would make of that criticism. The first is that we actually have a wide range of models, from actually very simple models of the, of the earth and how the climate system works, to these very complicated, state of the art models. And, they show the same thing. So, whether you use the stripped down model that includes greenhouse gases, the sun, and, and, and the things that we know are important, averaged over the surf- surface of the Earth, or you include more complicated models, you see the same result.

So I, I think there are a couple of things to recognize about climate models. The way they work is we, we take the, we try to estimate the range of uncertainty. In other words, what could be going on in the climate system if you make the most conservative assumptions about how greenhouse gases could be affecting, and you make the most defensible assumptions about how, how influential greenhouse gases could be.

You take those two ends of the re- the spectrum, you take your best guess in the middle, and then you can look at what the range of possibilities are. And, that’s how we move forward. You try to, you try to then narrow what’s possible as we learn more, and that’s what we’ve been doing as a, as a group. And, and consistently, we see changes in climate improvements in models that further show that climate’s changing and that humans are responsible for most of the climate changes that we’ve seen over the last several decades.

But, I also say that models are only one piece of the story. So, we have a whole range of other types of evidence that come into play, that show us that climate’s changing. We have observations of climate changes from way back, over the last several hundred thousand years. We can look at what greenhouse gases contributed, how they contributed to past climate changes. And, we can take just those and look at what we’re doing with greenhouse gases, and get an estimate of how much we would expect climate to change.

So, you have that as an independent source to check against. We also have observations, we have theoretical measurements, we have com- computational experiments and models and things like that.

You’re talking about core samples?

Well, core samples are one of the ways that scientists can look at past climates and understand what climate was like in the deep past.

They say it’s arrogant to think that man would be able to alter the climate cycles, and that’s  its natural causes.

Well, so it is true that there have been a number of ice ages in the past. We know that. And we understand why those ice ages occurred. In addition to that, those past ice ages, which had natural causes, we also know that humans are changing greenhouse gas concentrations, and we know and understand a great deal about why that would change climate. And, let me say that to reject what thousands of scientists have spent decades trying to understand is extremely arrogant.

We know an enormous amount about the climate system, and to say that it is arrogant to suggest humans could influence is itself extremely arrogant, because it is dismissing the vast amount of evidence that we have, that humans are, in fact, changing the climate.

A member of Congress has said there’s no causation shown, just correlation, that it could be caused by postal rate increases.

Well, the assertion is flat-out wrong. I mean, scientists have worked very hard to look at the changes in climate and to assess what the causes of those changes are. So, we’ve established, with a high level of certainty, a causal link between human emissions of greenhouse gases and the changes in climate that we’ve seen recently. So, that’s an active area of research.

There are a lot of scientists that have been engaged in that research, and have worked very hard to tease apart why climate has been changing. So, to suggest that there’s no correlation is essentially to reject an enormous amount of work by a great deal of leading scientific experts. It’s just flat out wrong.

What’s your take on the idea that this is alarmist?

Well, there are a couple of things about that. The first is I think that a large number of climate scientists are genuinely concerned. So I think there is a fair amount of fear among climate scientists about what the implications of climate change are for human societies, and I would certainly put myself in that camp. I’m deeply concerned about what the implications are of climate change to human well-being. So, I am afraid.

That’s different than being a fear-monger, which I think is really getting to the question, then in a different way. And, I would just say that science is a, in my view and in my experience, extremely conservative. So, the rewards in science are really for individuals for being right, and for contributing to our knowledge and understanding, and for not being wrong. If you’re wrong, all of your colleagues then have an incentive to show that you are wrong.

And they can show that you were wrong, and it shows that they know what they’re talking about, they’re contributing to our knowledge and understanding. So, it creates this strong conservative streak among scientists to try to be right and try to make sure that we don’t get ahead of what our research shows, what the data show. And if you do, then you open yourself up to criticism that you wouldn’t want to do.

So, there are strong checks and balances in science for being accurate, and strong checks and balance for not being …

Alarmist?

Alarmist, right. In what I think you mean by that definition of alarmist. But, I think there’s no question that an enormous number of scientists are alarmed, are deeply alarmed by climate change, but that’s very different than saying that they are alarmist. I think that is not consistent with how the scientific process and how the process of doing science works.

One of the members of Congress, who has been there through eight Presidents, said that the alarmists, they’re looking for a bogeyman, they want to change the way America behaves. He says that cow flatulence can create CO2, and our breathing every day creates CO2, it’s being produced everywhere, all the time.

Yeah, so some of that’s actually correct, but misleading. So, it’s true, when we exhale, we exhale CO2. And it’s true, there are a number of sources, natural sources of CO2. One thing to keep in mind about our exhaling CO2 is that we essentially consumed the carbon, recently, that we’re exhaling. So, that’s what we eat. And what we eat brought that carbon out of the atmosphere in the recent past.

So, it may be from crops that took it out of the air. It may be the animals that ate those crops or the plants that we’re eating. That’s a relatively short turnover time, from the atmosphere, to the crop, to our bodies, we exhale it. Coal, oil, natural gas are carbon that are out of the system. They’re stored away, when we pull those out and we burn them, we’re taking carbon that was sequestered, that was away from the atmosphere, and putting it into the atmosphere.

So, the natural sources and sinks of carbon were actually in balance before we came along. And, what we’ve done by going into these fossil reserves, energy reserves, is we’re adding additional CO2 into the atmosphere. So, that’s the cause of concern there.

Cows produce methane. Methane is a greenhouse gas. And that and methane concentrations in the atmosphere are increasing. CO2 concentrations in the atmosphere are also increasing. We know very well that humans are responsible for the increasing CO2 concentrations. I can’t say as much about methane, but we know very strongly that CO2 increases are directly resulting from human activities, and specifically burning of fossil fuels, primarily, but also some deforestation.

The same Senator says that too many windmills could stop the Earth from turning, or no one really knows what would happen in the long run.

[laughs] Well, we know that the Earth will continue turning, so that is inaccurate. I can’t speak to the specifics of what happens if we harvest a huge fraction of the energy in wind. But I think that the statement reveals that the member of Congress can’t really speak all that accurately to that either. I am vaguely aware that there’s some research on these questions of what happens if we harvest a whole lot of energy from wind.

I don’t think that there are any real concerns, and certainly not concerns that the Earth stops turning. [laughs]

Didn’t the earthquake in Chile affect the Earth’s rotation?

I can’t speak to that, but certainly we’re talking about, at most, a very small change. If you believe in subsidizing, well, I would just point out that if you want subsidies for things that cause societal damage, we know that that’s economically harmful, and our current situation involves a lot of economic harm. That is, we are currently subsidizing our emissions of greenhouse gases.

We’re subsidizing climate change, and that means we’re going to get more of it, and that means it’s economically harmful. And I’m tempted to say that whoever, you didn’t mention the name of your member of Congress, but if they want, essentially a socialized fossil fuel system, that’s really what they’re talking about.

Do you have anything you want to add?

There are a couple of questions that you might have, that you might’ve gotten to a little bit tangentially, that are at least worth being aware of. I don’t know whether I have a good answer for them, but sometimes people say that climate change and increasing CO2 concentrations will be beneficial.

A really important piece, and I’m sure somebody else you’ve talked to has gotten to this, but it gets to this idea of subsidizing climate change, and we’re currently in the situation where it’s a very hard landscape for renewables, it’s a hard landscape for reducing greenhouse gas emissions. Because essentially, when we all choose to drive, when we turn on a light switch, when we burn fossil fuels, we don’t pay for the full costs. We can shift those costs on to others in society.

That’s a subsidy, and it causes economic damage. And one of the things I’m sure you heard is this idea that putting a price on emissions would be economically harmful. And that’s a basic economic principle, runs counter to that. So, that argument, that putting a price on greenhouse gas emissions will be economically harmful, flies in the face of a basic economic principle, which is namely that currently we are subsidizing our emissions of greenhouse gases, and those subsidies are economically harmful, because it means that the people who cause climate change aren’t paying the costs of causing climate change.

We have heard that shifting the government’s support is going to destroy the economy.

I think that’s absolutely critical, and it is a misunderstanding of a basic economic principle. It is a basic economic principle. It contradicts this basic economic principle that by putting a price on emissions that captures the damages to climate that occur as a result of our emissions, you would expect net economic benefits to accrue as a result of that. That is a basic economic conclusion. There’s a second basic economic conclusion that I think is really important to keep in mind, and that is if you want less of something, in this case, greenhouse gas emissions, you almost certainly have to increase the price of those activities that cause greenhouse gas emissions.

So, those are the two key, basic economic principles to keep in mind.

Do you think the EPA’s findings of CO2 being a pollutant are warranted?

Well, I don’t know enough of the details, but what I can say is, CO2 is different than what we typically think of as a pollutant. So, it’s not acutely dangerous, we have CO2 in this room, for example, it’s not going to harm us acutely by inhaling it. But, there’s no question that the changes in climate that are being caused and will occur in the decades ahead as a result of increasing greenhouse gas concentrations, increasing CO2 concentrations in the atmosphere, no question that that poses very serious dangers to human health and human well-being.

If you had to name one thing that’s your biggest concern, what possibilities loom in the future?

I am most concerned about what climate change will mean to biological systems that we depend on for our health and well-being. So, biological systems are often very, very tightly adapted to the current climate conditions. And, we depend on biological systems in a wide range of ways that we usually take for granted.

So biological systems are important in flood and drought control. They provide pollinators for crops. They help cycling of nutrients that we need for our crops. They help control pests, help clean the air, help clean water, things like that. So, they provide a number of critical goods and services that really are the foundation for things like GDP, the Gross Domestic Product, and all of our economic activities. But, we don’t usually account for them when we think about things like GDP.

Those biological systems are heavily adapted to current climate conditions. We depend upon them strongly, and so my big concern is that climate change will be disruptive and damaging to biological systems, and then through those impacts, will have a big impact on human societies and human well-being. So, that’s the number one for me. The number two would be what it does to water resources. And water availability and water quality. Some of that’s tied to biological systems, but some of it is just tied directly to how water systems depend on the characteristics of climate.

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