PDF Summary:Unsettled, by Steven E. Koonin

Climate activists have misled the public into thinking there’s proof that our actions have led to global warming and possible climate catastrophe, according to former energy industry scientist Steven E. Koonin. On the contrary, Koonin argues that the facts about climate change are far from certain.

In his 2021 book, Unsettled, Koonin concedes that the climate is warming and humans are partially responsible for this warming. However, he contends that the evidence is overstated and climate scientists’ predictions are based on unreliable models. In turn, public misconceptions about climate change abound and the proposed solutions to climate change are unlikely to succeed.

In this guide, we’ll discuss Koonin’s assessment of climate science and its conclusions, in addition to his critique of prominent responses to climate change and his proposed alternative responses. Throughout this guide, we’ll also consider counterarguments from climate scientists and updates to climate science since Unsettled’s publication.

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(Shortform note: Although absolute record high temperatures aren’t becoming more frequent in the US, that doesn’t mean that extreme heat isn’t getting worse. After all, research indicates that heat waves—sustained periods of abnormally high temperatures—are becoming more frequent in American cities, as they only occurred twice annually in the 1960s, compared to six times annually in the 2020s. So, Koonin may be too quick in dismissing any trend toward extreme heat on the basis of record temperatures alone.)

In a similar vein, Koonin criticizes the US government’s 2014 National Climate Assessment (NCA), which reports that the intensity and frequency of North Atlantic hurricanes has been increasing since the 1980s. Once again, Koonin finds that this claim is misleading—upon examining the data on North Atlantic hurricanes dating back further to the 1940s, he says there’s no discernible long-term trend. In fact, any slight increase in hurricane activity from 1985 to 2010 is offset by a similar decrease from 1965 to 1985.

Indeed, Koonin notes that the IPCC’s fifth assessment report (AR5) confirms this result: In 2013, it reported low confidence in any long-term increase in hurricane activity. By extension, Koonin concludes there’s no evidence suggesting humans are responsible for an increase in hurricane activity—after all, we can’t be responsible for a trend that doesn’t exist.

(Shortform note: Recent findings from the IPCC’s sixth assessment report, AR6, tell a slightly different story from AR5: With respect to Atlantic hurricane activity in particular, AR6 reported with medium confidence that human activity has been partially responsible for increased hurricane activity since the 1970s.)

Finally, Koonin also questions a related pair of weather phenomena: floods and droughts. As for floods, Koonin asserts that the IPCC’s AR5 reported low confidence in any global trends regarding the magnitude and frequency of floods. So, according to the UN’s own climate scientists, we aren’t sure whether floods are increasing globally.

As for droughts, AR5 echoes the same sentiment: There’s little evidence that droughts are becoming more prevalent worldwide since the 1950s. Koonin notes that the same is true in the US specifically, as average drought conditions have shown no discernible trend since 1890.

(Shortform note: Since Unsettled’s publication in 2021, the UN has changed its analysis of droughts; in 2022, it reported that droughts had grown more severe and frequent worldwide since 2000. The report warns that in the coming decades, dozens of countries will face increased drought related to population growth and climate change.)

Misconception #2: Human Influences Are Making Sea Levels Rise

Koonin also casts doubt on the assertion that human activity is causing rising sea levels. Upon reviewing the scientific evidence, he contends that although sea levels are indeed rising, it’s unclear whether this rise is caused by human-induced climate change, rather than natural variation.

To put the recent rise in sea level in context, Koonin examines the average sea level over the last 400,000 years. He finds that the sea level repeatedly decreased by about 120 meters over 100,000 years, then rapidly rose about 120 meters over the next 20,000 years. So, the last 400,000 years have seen cycles of sea level changes that occur because shifts in the Earth’s orbit and tilt cause glaciers to either melt or grow larger.

(Shortform note: One way that we estimate past sea levels is by examining geological records. For example, if we find marine fossils in rocks that are presently above sea level, that suggests that those rocks were once below sea level. Thus, we can use these fossils as a proxy for determining past sea levels.)

Because the sea level rises and falls across these cycles, Koonin argues that we shouldn’t conclude that the recent rise in sea level is the result of human activity. Rather, he proposes comparing the sea level rise in recent decades—when human impact on the climate became most stark—with the sea level rise at the beginning of the 20th century, when our impact was negligible. In doing so, he aims to see whether there’s been any significant change in sea level rises that coincides with increased human impact on the climate; if so, that would provide evidence that human influences are responsible for recent sea level rises.

Accordingly, Koonin cites the IPCC’s findings that the sea level rose an average of 1.7 mm per year from 1901 to 2010. He also concedes that, between 1993 and 2010, the sea level rose an average of 3.2 mm per year. So, the sea level has indeed risen at a greater rate in recent decades. Yet, Koonin observes that periods of relatively higher sea level rises also occurred before humans were actively affecting the climate. For example, the IPCC also reports that the sea level rise between 1920 and 1950 was comparable to the rise between 1993 and 2010.

(Shortform note: Even if recent sea level rises aren’t necessarily the result of human activity, projections indicate that future sea levels will indeed depend on our efforts to curb carbon emissions: According to the IPCC’s 2019 report, sea levels will rise about 0.43 meters (or 5.3 mm annually) by 2100 if we aggressively limit our CO2 emissions, compared with 0.84 meters (or 10.4 mm annually) if we continue on our current trajectory.)

So Koonin concludes that we can’t rule out natural variation as the driving factor behind the recent increase in sea level rises. After all, similar rises occurred before human influences played a role, so it’s entirely possible that recent rises are also the result of natural factors.

(Shortform note: In False Alarm, Bjørn Lomborg proposes several ways that we could adapt to rising sea levels in the future. For instance, he recommends building dikes, which are coastal walls designed to prevent flooding. Alternatively, he also endorses “artificial nourishing,” which involves artificially adding sand to coastlines so that rising sea levels are less damaging.)

Misconception #3: Climate Change Will Lead to Catastrophe

Koonin also disputes predictions that climate change will lead to disaster in three areas: increased climate-related deaths, widespread food shortages, and economic turmoil. By appealing to the very models that some use to support these predictions, Koonin argues that climate change won’t cause widespread death, famine, or economic catastrophe.

1. Climate-Related Deaths

First, Koonin disputes economist Michael Greenstone’s projection that climate change will cause an additional 85 deaths per 100,000 people by 2100. On the contrary, he argues that Greenstone’s concern about climate-related deaths is overstated.

(Shortform note: Projections of climate-related deaths vary by model. For example, another influential 2021 study found that, under the baseline emissions scenario in which average temperature rises by 4.1°C, there will be 83 million excess deaths by 2100. This amounts to 4.6 million climate-related deaths annually in 2100, making climate change’s mortality rate comparable to those of obesity and air pollution.)

Koonin finds that, to make his projection, Greenstone’s model assumed the IPCC’s worst-case emissions scenario would occur, in which our carbon emissions triple and we’re responsible for 8.5 W/m² of the energy in the climate system. However, Koonin notes that a recent analysis suggests that this scenario is unlikely because we’re projected to reduce our coal consumption by the end of the century.

Rather, under the more realistic assumption that we’ll be responsible for 4.5 W/m² of the climate system’s energy by 2100, he observes that Greenstone’s model predicts a climate-related death rate of 14 per 100,000 by 2100—one-sixth of his stated estimate. Hence, according to Greenstone’s own model, climate-related deaths by 2100 will be far fewer than reported.

(Shortform note: Current projections estimate that the world population in 2100 will total 11.2 billion people. Consequently, even if Koonin is correct that climate-related deaths will have a mortality rate of 14 per 100,000 by 2100, that still means that over 1.5 million people will die annually because of climate change by 2100.)

2. Widespread Food Shortages

Next, Koonin criticizes a 2019 New York Times article reporting that climate change has contributed to global food shortages, according to an IPCC report. In response, Koon argues that the IPCC’s report doesn’t justify claims of food shortages.

Koonin notes that the IPCC’s report itself found that calories per capita have actually increased by about one-third globally since 1961. Moreover, he observes that from 1961 to 2011, our global crop yields have increased dramatically—wheat, rice, and corn yields have more than doubled.

According to Koonin, the IPCC’s report makes a more modest claim than reported by The New York Times: Crops yields are slightly lower than they would have been, because of human-induced climate change. For example, although the wheat yield rose 100% from 1981 to 2010, the IPCC estimated that it would have risen 104% in the absence of human-caused climate change. So, the IPCC’s report only justifies the modest claim that climate change has had a slight impact on global food yields.

(Shortform note: Other recent studies have suggested that the agricultural impact of anthropogenic climate change is greater than the IPCC’s report suggested. For instance, a 2021 study found that, although agricultural research has led to rising crop yields, human-induced climate change has decreased total agricultural output by about 21% since 1961. In other words, anthropogenic climate change has lost an equivalent of seven years of agricultural growth since 1961.)

3. Economic Turmoil

Finally, Koonin casts doubt on the US’s 2018 National Climate Assessment (NCA), which reported that climate change would substantially harm the US economy by 2100, arguing that climate change will have a nearly undetectable effect on economic growth.

To show as much, he notes that according to the IPCC’s 2014 report, AR5, the projected warming of 3°C by 2100 would cut the global economy by 3% by 2100, or 0.04% annually. Because the economy is otherwise projected to grow at a rate of 2%, Koonin predicts that climate change will instead slow that growth to 1.96%. In other words, climate change will have a nearly undetectable effect on economic growth.

(Shortform note: Koonin’s claim that climate change will have a negligible economic impact is arguably overstated. In False Alarm, Lomborg considers the economic effects of climate change over the next 500 years, rather than the effects by 2100 alone. Using the Dynamic Integrated Climate-Economy Model (DICE), he finds that climate change will cost 3.6% of global GDP by 2500, or $140 trillion—over six times the US GDP in 2021. Thus, by focusing on the yearly economic growth rate rather than the total loss in GDP, Koonin obscures climate change’s actual economic impact.)

Where Climate Science Went Wrong and How to Repair It

Following his arguments that climate science is frequently misconstrued, Koonin attempts to diagnose the root of this problem and propose a remedy. In this section, we’ll examine the various parties that Koonin accuses of distorting climate science, followed by his suggestions for repairing it.

The Parties That Distort Climate Science

Although Koonin argues that an array of parties bear responsibility for misrepresenting climate science, we’ll focus on three main ones: the media, politicians, and climate scientists themselves. According to Koonin, these parties knowingly misrepresent climate science out of their own self-interest.

Party #1: The Media

First, Koonin argues that the media’s climate stories often sacrifice accuracy in exchange for engagement. He clarifies that, because the media is a business, news outlets compete with one another for engagement—in the age of the internet, they compete for clicks. This business model leads to far-fetched headlines and stories, as such stories generate more engagement.

In the case of climate news, this incentivizes incendiary headlines, such as “Climate Scientists Warn of Incoming Doom.” In contrast, Koonin claims that more accurate headlines, such as, “Climate Scientists Unsure Whether Rising Sea Levels the Result of Human Influences,” aren’t newsworthy.

How Negativity Bias Might Influence Climate Headlines

The incendiary nature of climate headlines reflects a general trend of news becoming increasingly somber. Indeed, data scientist Kalev Leetaru finds that between 1945 and 2005, New York Times articles grew increasingly negative, which he views as evidence of lower levels of happiness as the century progressed.

Moreover, although consumers often claim to lament the negative state of the news, researchers find that in an experimental setting, consumers actually prefer to read negative stories rather than positive ones, when given the opportunity. According to these researchers, it’s possible that this preference stems from negativity bias—the fact that humans assign negative information more weight than positive information.

With respect to climate headlines in particular, then, it’s plausible that the alarming headlines that Koonin describes likewise play off our negativity bias. Simply put, we prefer to read negative news, and so are more attracted to negative climate change headlines. In turn, this explains why climate headlines featuring alarmist language attract more engagement than hopeful headlines.

Party #2: Politicians

Next, Koonin argues that politicians oversimplify complex issues to instill passion and loyalty in voters to win elections. Simple messages, Koonin claims, convey confidence and stoke voters’ passion, while voters view nuanced messages as a sign of uncertainty and weakness.

Consequently, with regard to climate change, politicians choose to convey uncompromising messages that win them votes. For progressives, this might involve claiming that climate change is an apocalyptic threat requiring drastic actions; for conservatives, this might involve claiming that climate change is simply a hoax. So, Koonin concludes that politicians across the political spectrum misrepresent climate science to their own benefit.

(Shortform note: Evidence suggests that these views have gotten more entrenched in recent years; one 2019 study reports that, since 2010, an increasing percentage of Democrats view climate change as a serious threat, while an increasing percentage of conservative Republicans denies that climate change is a threat altogether.)

Party #3: Climate Scientists

Finally, Koonin argues that climate scientists face external pressures to pump up their findings. For instance, journals prefer to publish conclusive results, which obscures the uncertainty that afflicts climate science. Similarly, grant foundations only renew funding for researchers with clear findings, which encourages scientists to downplay any doubt in their findings. Moreover, climate scientists’ own peers expect them to conform to the narrative that climate change is catastrophic since that justifies the field’s importance.

(Shortform note: Some journals’ unwillingness to publish inconclusive results is a form of publication bias, the practice of selectively publishing articles based on their results. In this case, publication bias may make it easier to publish articles with positive results about climate change than those with negative results about climate change.)

How to Repair Climate Science

Koonin argues that despite the grim state of climate science, it’s possible to improve scientific reports on climate change and their portrayal to the general public. In particular, he proposes concrete strategies for making climate science more transparent and accessible to the layperson.

To begin, Koonin advocates third-party review of climate reports themselves—specifically, the US’s NCA reports and the UN’s IPCC reports. In order to strengthen confidence in these reports and expose possible flaws, Koonin recommends a “Red Team review,” in which an external group of scientists scrutinizes the reports and presents possible counterarguments to their findings. Such a review, Koonin notes, is common practice in national security reports, so it has precedent in other consequential fields.

(Shortform note: In addition to Red Team reviews, government proposals are also subjected to several other reviews as the proposal nears completion. For instance, Blue Team reviews occur around the outline phase, making sure that the outline is complete and doesn’t have any obvious flaws. Next, a Pink Team review examines a more fleshed-out document, looking for factual errors and red flags not found in the previous review. Traditionally, the Red Team review only occurs after these previous reviews.)

With respect to climate reports, Koonin argues they have two features that justify a Red Team review. First, climate reports are written under the auspices of self-interested governments, which suggests that bias could infiltrate them; a Red Team review could help mitigate this concern. Second, unlike papers published in academic journals, the NCA and IPCC reports aren’t reviewed by a referee who can require changes—although referees do review the reports, the original authors have the authority to overrule referees’ comments. So, a Red Team review could help check the authors’ unrestrained authority.

(Shortform note: While Koonin’s concern about authors’ unchecked authority is valid, similar concerns have been voiced about the anonymous referees of academic journals; some argue that anonymity leaves referees free to make arbitrary requests without accountability. Nonetheless, anonymous review remains the norm in academic publishing, though the British Medical Journal abandoned the practice in 1999.)

Beyond improving climate reports themselves, Koonin also suggests ways to increase public understanding of climate science. Because most laypeople learn about climate change from the media, Koonin argues that they need to learn to distinguish between reliable and unreliable climate reporting. He lists various warning signs indicating that a particular climate story in the media is unreliable:

• Referring to climate scientists as “deniers” on the one hand, or “alarmists” on the other, suggests a drift into propaganda.
• Conflating climate and weather illustrates a basic misunderstanding of climate science.
• Reproducing statistics without context reveals a desire to persuade rather than inform.
• Failing to provide hard data at all shows little concern for precision and accuracy.

By heeding these warning signs, Koonin suggests that the public can better determine whether a media report is reliable.

(Shortform note: To supplement Koonin’s warning signs, experts offer several other ways to tell whether a scientific story is reliable. For example, be wary of emotionally loaded language, which can suggest a lack of objectivity. Additionally, examine the studies cited in the story to see whether they’re in reputable, peer-reviewed journals.)

Possible Responses to Climate Change

Because of the distortion of climate science, Koonin argues that many governments have endorsed impractical responses to climate change. In this section, we’ll first discuss Koonin’s argument that the goal of eliminating carbon emissions is virtually impossible, followed by his proposed alternative responses to mitigate climate change and its effects.

The Impracticality of Eliminating Carbon Emissions

As Koonin notes, one straightforward response to climate change involves eliminating carbon emissions altogether. Indeed, the IPCC claims this response is actually necessary to meet the goals of the Paris Agreement—an international climate accord among 196 nations that aims to keep warming below 2°C by 2100. Koonin, however, argues that eliminating carbon emissions by 2100 is practically impossible because growing energy demands preclude such a radical overhaul of the energy system.

(Shortform note: The Paris Agreement is unlikely to meet its main goals. First, the UN’s own climate scientists reported that the Paris Agreement won’t keep global warming below 2°C by 2100, even if all participating countries keep their promises. Moreover, though wealthy members of the Paris Agreement promised to raise $100 billion by 2020 to establish a climate fund for impoverished countries, that goal was also not met.)

To make his argument, Koonin first cites projections that worldwide energy demands will increase by 50% by 2050. Moreover, fossil fuels are still projected to account for 70% of global energy by 2050. Because fossil fuels—which emit CO₂ when burned—are expected to play a crucial role in fulfilling these energy needs, Koonin reasons that eliminating CO₂ emissions altogether would require transforming the energy system.

(Shortform note: Experts estimate that, at our current rate of clean energy expansion, it would take about 400 years to develop an energy system capable of keeping global warming below 2°C. Given some estimates that we only have until 2030 to avert climate catastrophe, however, overhauling the energy system in 400 years is likely far too late.)

Next, he argues that such an overhaul would require emissions constraints that are enforced worldwide; otherwise, high-emissions activities would relocate to areas that lack these constraints. However, this would require impoverished countries to voluntarily stunt their growth by forswearing much-needed emissions—emissions that could otherwise help address pressing problems like housing, transportation, and water sanitation.

So, given the degree of self-sacrifice required, Koonin concludes that a globally coordinated effort to eliminate carbon emissions is unlikely to occur. Rather, he claims that fossil fuels will continue to play a pivotal role in meeting our energy needs for the foreseeable future, making the transition to carbon neutrality impossible.

(Shortform note: In False Alarm, Lomborg likewise claims that developing countries are unlikely to switch to clean energy, given the costs to their economies. Consequently, he argues that stimulating economic growth in these countries is itself an important climate policy—for instance, by funding schools that teach marketable skills and opening up markets to international trade.)

Alternative Responses to Climate Change

Because of his skepticism about our ability to curb emissions, Koonin considers alternative responses to climate change. In particular, he argues that we should consider geoengineering and adaptation in order to address climate change.

First, Koonin examines geoengineering—active techniques designed to artificially reduce the earth’s temperature—and argues that two forms of geoengineering are worth considering: Solar Radiation Management (SRM) and Carbon Dioxide Removal (CDR).

Broadly speaking, SRM involves making the earth more reflective to decrease the heat absorbed at its surface. According to Koonin, the most promising form of SRM is aerosol injection, which involves injecting aerosols into the stratosphere to create a reflective haze. Specifically, he claims we could insert a safe amount of hydrogen sulfide into the stratosphere at a relatively low cost, which would offset the warming caused by our CO₂ emissions.

(Shortform note: Although Koonin focuses on stratospheric aerosol injection, there are several other forms of SRM that have been researched. For example, cirrus cloud thinning attempts to either thin or altogether get rid of high-altitude cirrus clouds, allowing more heat to escape into space. Moreover, marine cloud brightening attempts to brighten marine stratocumulus clouds, in turn reflecting more sunlight back into space.)

Nonetheless, Koonin concedes that this form of SRM has several disadvantages. For example, because the aerosols dissipate quickly, we would have to sustain the haze long-term to keep surface temperature low. In addition, climate models suggest that SRM could have adverse effects on the climate, which could be worse than the rising temperature itself.

(Shortform note: In addition to these disadvantages, experts warn that stratospheric aerosol injection could lead to increased Arctic ozone depletion, which has further harmful consequences itself.)

So, Koonin turns to CDR as another promising form of geoengineering. Put simply, CDR involves removing CO₂ from the atmosphere and storing it elsewhere. Koonin argues that this form of geoengineering has multiple advantages. For instance, CDR would allow us to continue using fossil fuels to meet global energy demands, rather than developing alternative energy sources. Moreover, because CDR involves restoring the atmosphere to its natural level of CO₂ concentration, it would likely have few adverse effects on the climate.

However, Koonin admits that we currently lack the infrastructure to use CDR on a meaningful scale. In particular, he asserts that removing even 10 gigatons (10 billion tons) of CO₂ from the atmosphere—about one-third of our annual emissions—would require an infrastructure of similar size to our current fossil fuel infrastructure. So, although CDR could help mitigate climate change in the distant future, Koonin suggests that it isn’t yet a viable approach.

(Shortform note: Although CDR isn’t a viable option yet, several companies are constructing larger CDR facilities, suggesting that it might be viable at some point in the future. For instance, in 2022 the Swiss company Climeworks announced plans for Mammoth, a CDR facility designed to remove 36,000 tons of CO₂ each year.)

In light of these challenges for geoengineering, Koonin argues that adaptation will be our primary response to climate change. After all, adaptation has been our response to hostile environments throughout history, as we learned to survive in Arctic and tropical regions by adapting. Similarly, Koonin suggests that adaptation will overshadow our efforts to either mitigate climate change by curbing emissions or negate its effects through geoengineering.

Concrete Ways to Adapt to Climate Change

Despite his argument that adaptation will be our primary response to climate change, Koonin doesn’t offer concrete forms of adaptation to help us cope with climate change. Lomborg, however, does just that. In False Alarm, he suggests the following forms of adaptation to minimize the damage from climate change:

• Create floodplains and invest in vegetated urban areas that better absorb water to reduce damage from climate change-induced flooding.

• Invest in early-warning systems and disaster response systems to minimize the harms of extreme weather.

• Paint roofs and roads in urban areas with light-colored coatings to reduce temperatures in cities.

• Implement building codes that prevent houses from being built in high-risk areas to decrease the damage from wildfires.