be settled? In this episode, I’m joined by Steven E. Koonin to discuss the consensus within
the climate science community, popular misconceptions about the climate, and how we
should respond to warming global temperatures given the costs climate change will impose
down the road and the costs of cutting our carbon emissions today.
Steve is a professor at New York University and a nonresident senior fellow here at the
American Enterprise Institute. Previously, he served as the Under Secretary for Science at the
US Department of Energy under Barack Obama from 2009 to 2011. This year, he
published Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters.
What follows is a lightly edited transcript of our conversation. You can download the episode
here, and don’t forget to subscribe to my podcast on iTunes or Stitcher. Tell your friends,
leave a review.
Pethokoukis: Your book is titled “Unsettled” and the point is that climate
science is not settled; science is never settled. But has the science grown
stronger? Has it grown more certain since the early ’90s when Al Gore came out
with his “Earth in the Balance” book, or maybe the early 2000s when he came
out with “An Inconvenient Truth”? Do we know more and do you feel more
confident in the science?
Koonin: Certainly given the passage of 30 years and spending of God knows how many tens
of billions of dollars, of course we understand much more about the climate system now than
we did when Al Gore wrote his book. Some things have become more certain. And at the
same time, we’re starting to realize the limits of our current understanding.
What have we become more certain about and what have we become less
certain about? And does the combination of both make you more concerned
about the climate?
So for example, again, going back 30 years, there was still some doubt about what the global
average temperature anomaly was doing. There were conflicting measurements on the
ground. It’s gotten much better now. We know that the globe has warmed about 1.1 degrees
since 1900. We also have good confidence now that the planet is gaining energy — that
there’s more energy being absorbed from sunlight than the planet is radiating out into space.
That’s a very tricky thing to measure. It’s a fraction of a percent effect, but nevertheless, we’re
quite confident that that’s happening.
Are there things that people were really confident of 30 years ago or 15 years
ago that we’ve become less confident of? 1) Are we becoming less confident
about some things? 2) What are the big questions where we need a lot more
research and we’re not sure at all?
I think one of the big questions is the natural variability of the climate system. Maybe not so
much for the global temperature, but that in some ways is a theoretical construct of interest
only to scientists. What’s really of interest is what’s happening with local weather, sea level
rise, storms, floods, droughts, and so on. And there I think we’re starting to understand just
how variable all of those things are on a multi-decade or century timescale.
Let’s put aside the worst projections. Should what we have learned make us
more concerned than we were 20 years ago because either the potential
outcomes are worse or we’re more certain about those outcomes?
I think we should be less concerned. And of course, your matter of concern depends a little
bit on where you sit. And so I sit as a citizen of a developed world country and I’m not starved
for energy. If I were somebody in China and India, I might have a different set of concerns,
but my own concern has been tempered by realizing just how adaptable human society is.
Again, if you look at the 20th century, as the globe warmed a degree, we saw the greatest
improvement in human welfare ever as the population quadrupled from two billion to
roughly eight billion people.
And if you look at the projections of what’s going to happen with the global temperature by
the end of this century, we’ll see another one and a half degrees roughly, and that’s not going
to make civilization fall apart. Come on, it’s not going to happen at all. And in fact, the IPCC
says that. It’s says that compared to other forces, demographics, technology, regulation, trade
and so on, climate is a relatively small impact on the economy.
You’re living in a developed country, and you were born in the 20th century. If
you were going to be born early in the next century, would you be more
I think we should believe that our great-great-grandchildren will be every bit as adaptable
and more clever and better off than we are. And again, let’s remember that those of us in the
developed world are only 1.5 billion people. There are 6.5 billion people that are scrambling
up the developmental ladder. They are going to need energy and the more of it that they can
get, the better they’re going to be by the end of the century.
I want to read a quote from a paper by the late economist Martin Weitzman
called “Some Basic Economics of Extreme Climate Change.” You’re probably
familiar with it. And again, the listeners love when I read so I always try to read
at least once during the podcast:
Climate change is characterized by deep structural uncertainty in the science coupled
with an economic inability to evaluate meaningfully the welfare losses from high
temperature changes. The probability of a disastrous collapse of planetary welfare from
too much CO2 is non-negligible, even if this low probability is not objectively knowable.
Does that make sense to you? And if it does, does it suggest action?
There’s a famous quote by Lord Kelvin, I think: “If you can’t measure it, your knowledge is of
the most meager kind.” And unless you can quantify those probabilities, it hardly makes
sense to think about them. Of course, all kinds of crazy things can happen, but unless you can
put a number on it and say, “There’s a one-in-10-to-the-fifth chance of something happening
and it will cost this much,” you can’t sensibly think about it. All you have is emotion.
There are many crazy things that could happen (the proverbial asteroid, etc.) and we just get
on with life. With respect to the climate system itself, there was a paper last summer in which
four noted mainstream economists analyzed eight different tipping points, including the
proverbial outcasting of the permafrost, the slowing down of the Atlantic circulation, the
desertification of the Amazon, and so on. And it turns out that those add about 1 percent or 2
percent to the economic damages at the end of the century, which were already a couple
percent for a couple of degrees temperature rise. So at least the best mainstream economic
thinking is the economic damages of rising temperatures including tipping points are at the
percent level, a nothing burger.
Do you think about climate science in a way that’s different from full-time
climate scientists, or is it that what they say to each other is different than what
ends up being filtered through the media and through non-experts?
It is the latter. Of course, you can’t generalize to everybody, but the conversations I’ve had
about the science (as opposed to the emotion or the concern, if you like) are quite fine and no
different than what I’ve written in the book. It’s when you start talking to the public or they
start talking to the public either individually or institutionally that you start to get the
Well, I would assume that is because they feel the problem is serious enough
that some action needs to be taken. But given that perhaps the most severe
consequences would not happen for some time — it’s tough enough to get people
to act about near-term problems, much less problems that could really escalate
in 100 years — without a more severe or dystopian scenario, nothing will be
done. I imagine that would be the reason. Is that your take?
For sure, I think it’s some of that. In other cases it’s prominence, it’s funding, and so on. I’ve
given scientific advice in many other forums, fields, about things very different than climate.
I think it’s advisory malpractice to be misportraying the certainties and uncertainties in the
service of getting something to happen. Because, in fact, what you would like to happen
depends upon where you sit.
I keep coming back again to the six-plus billion people who don’t have adequate energy. And
if you’re going to force them to go to forms of energy that are less convenient or more
expensive or less reliable, I would say that that’s immoral. And so I think our jobs as
scientists are to represent the certainties and uncertainties as completely and as neutrally as
we can and let the decision-makers, the political sphere, the private sector make the
Are the climate models better than they used to be?
I would say they are more sophisticated, but in terms of providing actionable information,
they’re not much good at all. And again, this is not Steve talking. I can point you to papers
written by mainstream climate modelers who say people trust their local predictions, storms,
droughts, sea level rise, and so on, much more than vthey should.
We spoke a little bit about the temperature rise. What are some other impacts?
What do we know about those? Whether some areas may be drier, maybe some
wetter, melting ice caps . . . So what do we know about all the sort of spillover
effects from that overall aggregate rise in temperature?
We look historically. What we’ve observed so far: There are no long-term trends in
hurricanes or more generally tropical cyclones, as they’re called technically. And I think
many people find that as a surprise. Over the last, roughly almost a century, we see no
detectable trends in hurricanes. We do see for about the last 70 years some intensification of
precipitation over the land. And we see that in the US rainfall has gotten more intense, but
not necessarily more plentiful, in the Northeast, the upper Midwest, and the Northwest.
In terms of record-high temperatures in the US, they’re no more common today than they
were 100 years ago. Yes, sea level rise globally has been accelerating for the last several
decades, but it was also doing the same thing in the 1930s when, in fact, human influences
were much smaller. So a lot of what we’re seeing can be put down to natural variability, or at
least we need to show that it’s not natural variability. And that’s pretty hard without longterm
and precise records.
Going forward, we predict the temperature will go up. And there are predictions, but it’s
pretty difficult with a lot of uncertainty, about faster sea level rise, 10 percent more
hurricanes, for example, some intensification of floods and droughts, but we haven’t seen it
yet. And the temperature has already gone up by a degree. So it remains to be seen.
On whom should the burden of proof fall? Certainly some would say that we’re
doing something unusual to the planet; we may not fully understand the
impacts of this thing we’re doing, and we only have one planet. There are worstcase
scenarios in the average temperature rise. So should the burden of proof
be on the climatologists who are worried, or should it be on people who think
it’s not as bad of a problem and we should be very cautious before acting?
I don’t think the scientists need to prove anything. The scientists just need to state what we
know and what we don’t know. And your question is, what do we do about it? And that is very
much, as I’ve emphasized in the book and other presentations, a values discussion. It
depends upon development, intergenerational equity, North-South equity, and things of that
sort. And of course, what can you really do to make a difference? And I think we’ve reached a
stage in the climate and energy discussion where people who advocate doing something are
starting to realize just how difficult it’s going to be to reduce or even slow the growth of
human influences on the climate.
Has the “doing something” argument, and maybe you are suggesting it has,
been changing? Is it something different now than it was 30 years ago or 10
Oh yeah. I think there’s, at least among the experts, a better understanding of just how
difficult it is to change the energy system or to build a reliable energy system in the
developing world. I’ve been reading recently a seminal paper by a guy named Anthony
Downs, who was writing in the ’70s. And he talked about the cycle of issue acceptance or
issue prominence. Public issues, at least in the West, go through a series of five phases where
at first it’s only among the experts, then suddenly the public realizes that there is a problem
and great enthusiasm for solving it. Stage three is they realize just how difficult it’s going to
be to solve it. Stage four, then stage five: It fades into the background.
I think we are well into stage three now, when you look at what happened in Glasgow where
basically China and India and a couple of the other developing countries said, “We need
energy and we’ve got the wolf at the door. We got to worry about that. And maybe a couple of
generations from now we’ll worry about our emissions.” And that’s not an unreasonable
attitude for them to take. We in the US, EU will have a different attitude, but unfortunately,
the US is only 13 percent of global emissions. And even if we went to zero, it would be wiped
out by the growth in the rest of the world within a decade.
In developed countries — Europe, United States, Japan, Korea — how strong is
the push that we need to do something and that something needs to be living
very different kinds of lives? Yes, we need to change the power mix (more solar
and wind) but life as the West has lived it needs to be different.
Well, there are certainly some people who say that. But I think if you put that to a poll in the
US or in Europe, the answer would be, “Hell no.” Downs has this wonderful quote; I’ll see if I
can repeat it. That, “An environmental problem for the elites is just the common man
catching up.” In the ’40s and ’50s people were worried about pollution from automobiles.
Before that, it was only the elites who had automobiles and pollution was not an issue. It
passed out of the periphery in the US, and suddenly everybody got concerned about air
pollution. And so I think the greenhouse gas problem has got something of that flavor when
you compare the different stances of the developed versus developing worlds.
Speaking of elites, where do you think the policy debate is right now in
Washington? How much interest do you sense is there in policies that are about
us changing our way of life versus policies that are about, “Well, let’s be worried
about dirty power; we’ll try to create more clean power, but we’re going to
create more power”?
I think the policies that the Biden administration has put out are too much too fast. There’s
an optimal pace for decarbonization. If you do it too rapidly, you create a lot of disruption
because energy is very important and is central to society. If you do it too slowly, you incur
more risk from growing human influences. But what is being proposed — zero emissions
from electrical power by 2035, the effective disappearance of all internal combustion engines
being sold for vehicles — I think most people would say that that’s much too fast and it’s not
going to happen anyway.
We can’t build a clean grid with today’s technology unless either storage technology gets a lot
better to buffer wind and solar, or we deploy a lot more nuclear power than we have
deployed, or we deploy a lot more carbon capture and storage. And neither the electrical
storage with batteries nor nuclear power nor carbon capture nor storage can be deployed
rapidly enough and economically enough to reach the 2035 goal.
So the politicians have just gotten out over their skis. Somebody needs to sit down and
formulate an integrated plan for decarbonization that includes technology development,
regulation, economics (people still need to make money by providing energy), and consumer
or public perception. Nobody has done that yet. And I would think that that’s a necessary
prerequisite if we’re going to achieve any significant emissions reductions in the US.
Do you think we do need to decarbonize?
I think on the longer time scale, whether we need to or not, we probably will. Coal is just
disappearing. Natural gas is better than coal. Whether natural gas will disappear or not, I
don’t know. But again, the “we” maybe is the US, but as I mentioned, this is a global issue.
You’ve got to get China and India and the rest of the six billion people out there to
decarbonize. And I don’t see great enthusiasm for that.
Some people might view any critique of the popular, non-scientific consensus as
saying, “We should do nothing. It doesn’t matter how much carbon we pump
into the atmosphere because it doesn’t make a difference.” Is that what you’re
No, I wouldn’t say that. I think we do need to reduce our emissions, but I would do it on a
centennial timescale. Look, this is just one more issue. And it’s not the existential threat that
everybody believes it is — not everybody. If you read carefully the IPCC report that just came
out in August, you don’t find the words “climate catastrophe,” “existential threat,” or “climate
disaster” in it at all. You find “climate crisis “once in the report, and that refers to how the
media have dumbed down the description rather than any scientific finding. So it’s not a
crisis. It’s a problem to be dealt with in the most graceful way that we can.
Do you have thoughts about geoengineering or climate engineering as a kind of
a break-the-glass option if we’re all wrong and things get bad fast?
Yeah, I just did geoengineering for my climate science class at NYU last night, so it’s fresh.
Although, I wrote or convened the writing of a report back in 2007 that dealt with some
aspect of geoengineering. So I’ve been thinking about this for 15 years or so. So there are two
modes. One is that we suck carbon dioxide out of the atmosphere, and it’s hard to be against
that. We could do that by planting more trees or by physical, chemical methods. Planting
trees is kind of a no-brainer. Why not? And Congress is thinking about or it has already
allocated money: the Trillion Trees Act as it’s called. But it takes a long time to grow the trees
up and so on.
The other mode is to make the Earth a little bit more shiny to reflect a little bit more sunlight.
You don’t need to reflect much more. The Earth right now reflects about 30 percent of the
sunlight. If it were 31 percent, it would counteract almost all the warming effect of
greenhouse gases produced by humans that we’ve seen so far. And there are schemes to do
that. You could put particles up in the stratosphere. You could try to make particles over the
ocean a little bit more common, things of that sort. I think it’s a subject that needs to be
researched. And compared to 15 years ago, you can now talk about it in polite company,
because people are starting to realize how hard it is to reduce emissions.
I think it needs to be researched. I think we need trials, experiments, not on a global scale,
but locally. And then we would know whether or not we’ve got that as a tool to deploy, but
doing the research is very different than actually putting it into practice. That is a very tricky
situation having do with equity among nations, close monitoring of the effects if you started
to do it, things of that sort. So I’m all for the research. I’m very much against deployment
except in an extreme situation and with full discussion among all the world’s nations about
What is the argument you would make or the policy advice that you would give
that might be persuasive to lawmakers, Democrats, folks on the left who are
probably very concerned and are probably always being flooded with
information from activists painting a very apocalyptic scenario? What is sort of
the advice and message you would give those folks?
I would say the first thing to do is to cancel the climate crisis, namely to tell people there is no
emergency here. This is a complex problem that has different facets and different solutions.
So first of all, let us stand back and take a much better understanding of the problem.
Climate literacy and energy literacy are woefully lacking among policymakers. And the
second thing I would do is let us sit down and formulate a plan that will gracefully let us
reduce emissions without disrupting the economy, employment, the way people live their
lives as you mentioned, or the nation’s geopolitical standing and its dependence upon foreign
sources of energy, which of course are coming back into prominence as this administration
has cut back on domestic fossil fuel production.
First of all, declare there’s no crisis. Stand back, think it through, get everybody to agree on a
path forward, and then implement that. I mean, that’s not so specific, but I think elements of
those plans to get a little more specific will be the development of small modular nuclear
reactors, a push to develop battery storage longer term, a push on fusion energy, which has
seen some interesting progress in the last year or so, things of that sort. But is the world
going to end in 10 years or 20 years? Absolutely not. Come on.