Just over three decades ago, the United Nations Framework Convention on Climate Change (UNFCCC) was signed by President George H. W. Bush in Rio de Janeiro. It has one objective: to stabilize concentrations of greenhouse gases in the atmosphere so as to prevent “dangerous anthropogenic interference with the climate system.” This objective incorporates three assumptions that collectively constitute a scientific and policy paradigm of climate change.
The first assumption is that climate change is caused exclusively by human emissions of greenhouse gases, principally from the combustion of fossil fuels. The second asserts that all the climate impacts from burning fossil fuels are unambiguously bad for people and planet. The third is that the solution is the progressive—and preferably rapid—elimination of fossil fuels, requiring mankind to do without its main source of energy.
Five presidents and a generation later, this paradigm has been elevated into an overriding planetary imperative. Yet on its own terms, the UNFCCC has failed. In the ten years before it was signed, global emissions of carbon dioxide rose from 18.88 giga-tonnes (GT) in 1982 to 22.58 GT in 1992, a decadal increase of 3.70 GT. By 2022, CO2 emissions had risen to 37.49 GT, implying an average decadal increase of 4.97 GT—a rise 34% higher than the increase in the decade prior to the UNFCCC. Despite the UNFCCC being further from its stated objective—global net-zero emissions of greenhouse gases—than when it was signed, paradoxically, the three assumptions that underpin it have hardened into unquestioned and unquestionable propositions driving the West’s futile attempt to decarbonize the global economy. Seen in these terms, the UNFCCC might well be the most consequential international agreement of all time.
Initially, these propositions did not command the universal assent of climate scientists. In its first assessment report, released in 1990, the Intergovernmental Panel on Climate Change (IPCC) observed that the average global temperature had increased by between 0.3°C and 0.6°C over the previous hundred years. “The size of this warming is broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability,” the IPCC declared.
Pursuant to the convention’s first proposition, the IPCC’s equivocation gave way to increasingly confident statements ascribing the rise in global temperature to human emissions of greenhouse gases. Pressure to make the science conform to the politics was the cause of the IPCC’s first scientific scandal, in 1995, when the Clinton administration leaned on the IPCC to delete sentences that contradicted the second assessment report’s topline claim, written in concert with government representatives, that a balance of evidence suggested a “discernible human impact on global climate.”
A minority of climate scientists have consistently rejected the three axioms of government-approved climate science, a notable exponent being MIT’s Richard Lindzen. Rarer still, and possibly unique, is the climate scientist who once subscribed to the three propositions but subsequently changed her mind. Such is Judith Curry. That alone makes her new book, Climate Uncertainty and Risk, exceptional. Subtitled Rethinking Our Response, the book not only challenges the third UN climate proposition on policy responses but rethinks the first and second.
Moreover, Curry’s position differs from leading dissenters such as Lindzen. In a July 2023 comment letter on the EPA’s proposed fossil-fuel power-plant rule, Lindzen and physicist Will Happer wrote that while more carbon dioxide in the atmosphere is likely to cause some surface warming, the effect “would be small and benign” and diminish with each increment added to the atmosphere. From now on,
our emissions from burning fossil fuels have little impact on global warming. We could double atmospheric CO2 to 840 ppm [parts per million] and have little warming effect.
Curry disagrees. “Yes,” she writes in Climate Uncertainty and Risk, “CO2 emissions are a problem and should be reduced, but not as an urgent problem that trumps the need for abundant, reliable, and secure sources of energy for the global population.” In her book, Curry questions, rethinks, and rejects the three propositions of the UN climate-change paradigm, and she replaces the paradigm with a new one.
Proposition #1: Rehabilitate natural variability
Politicization of climate science became institutionalized with the setting up of the IPCC in 1988, in order to support a political agenda that would be adopted in the UNFCCC’s focus on “dangerous anthropogenic interference.” Its effect has been to marginalize scientific research into, and concern about, natural climate variability. Successive assessment reports ratcheted up the IPCC’s confidence in attributing it to human causation. Thus, in the IPCC’s 2018 Special Report on Global Warming of 1.5°C, which paved the way for net zero by 2050, the IPCC opined that natural variability contributed less than one-tenth of one degree Celsius to the one degree warming from 1890 to 2010.
The conceit of the UNFCCC and the IPCC is that without fossil-fuel emissions, there would be no climate change. Model simulations of internal climate variability are too weak over multi-decadal time scales; and averaging a large number of simulations with different phasing assumptions nets out the effects of internal climate variability. Ignoring internal climate variability in predictions of future warming runs the risk of overestimating warming over the next two to three decades, Curry warns.
Since 1995, we have been in the warming phase of the 60–80-year Atlantic Multidecadal Oscillation (AMO), which is shortly expected to shift to a cooling phase that has a peak-to-trough impact on global temperature of 0.3°C–0.4°C. The effect of volcanoes is also left out of computer climate projections, and the past 150 years have been relatively quiet in terms of volcanic eruptions decreasing global temperature. How much cooling could there be from volcanoes over the rest of this century? Curry asks. Then there is the impact of solar variations. Solar activity in the second half of the twentieth century is estimated to have been the highest in the last 8,000 years; yet the IPCC’s treatment is worse than negligent. Curry quotes a researcher who says that “the sun/climate debate is one of these issues where the IPCC’s ‘consensus’ statements were prematurely achieved through the suppression of dissenting scientific opinions.”
Incorporating the main components of natural variability produces a very different picture of future climate change from that promoted by the IPCC. When summed, Curry writes, “their magnitude approaches, or could even exceed, the magnitude of the emissions-driven warming for the next three decades.” What game is the IPCC playing by excluding the probable effects of natural variability? Its climate projections are deployed to promote the UN’s net-zero climate agenda. By contrast, the climate scenarios that Curry outlines are designed to inform practical decision-making. The outcome is that the IPCC risks badly misleading policymakers. In its efforts to fight climate change, the European Commission is consulting on proposals for “solar radiation modification” by seeding man-made aerosols in the stratosphere to artificially bring about falling global temperatures when they might be falling, anyway. That could very well bring about a genuine climate catastrophe.
In similar vein, the IPCC keeps policymakers in the dark about the presence of 183 volcanoes under the West Antarctic ice sheet, producing a steady flux of heat, something that net zero can do nothing to affect. Even more reprehensible than this omission is the IPCC’s promotion of the discredited RCP 8.5 climate scenario, which Curry says biases climate assessments in an alarming direction, the outcome—presumably intended—being that “the scientific literature has become imbalanced in an apocalyptic direction.”
Curry also has harsh words for economists who dip their toes into climate science to fabricate spurious climate catastrophes from so-called fat-tail distributions that have no scientific validity, their extreme values “unjustified by either observations or theoretical understanding.” In any case, brandishing catastrophic fat tails to justify draconian emissions cuts does not remove the sting from the fat tail:
If unknown tipping points exist that are associated with natural climate processes, there can be no certainty that the risk of climate catastrophe would be eliminated even if emissions fell to zero.
Even the virtuous risked being damned by a fat tail.
Proposition #2: Restore balance to assessing climate-change impacts
The fundamental presumption of the UNFCCC is that human-caused climate change is dangerous and that all its impacts are bad. As Curry points out, this is irrational: “Few would choose the pre-industrial climate of the eighteenth century.” If the world’s climate were warming solely owing to natural causes, it is unlikely that humanity would feel obligated to slow down future warming.
People would adapt to the changing climate as they always have.… There would be no motivation to attribute every extreme weather event to the warming, because there would be no political gain to be obtained from such attribution.
The first half of the twentieth century had more extreme weather than the second half. “The disconnect between historical data for the past 100 years and climate model–based projections of worsening extreme weather presents a real conundrum,” comments Curry.
A warmer climate is associated with more rainfall, notably in regions affected by the Asian monsoon. At least 60% of the region’s agriculture is rain-fed, and these areas are home to about half the world’s population. For this reason, the Asian monsoon is one of the most studied weather systems in the world. If climate policy were decided by popular vote, wonders Curry, would a majority vote for more CO2 emissions so that there would be greater water availability?
Proposition #3: Prioritize adaptation to a changing climate
In terms of policy responses, the first two of Curry’s propositions point away from the UN’s goal of rapidly phasing out fossil fuels toward adaptation as the rational policy response. As Curry notes, climate activists view adaptation as undermining the cause of emissions cuts, a message reinforced by the IPCC and its drumbeat of alarm about a “brief and rapidly closing window to secure a liveable future.” The IPCC’s view of a liveable future excludes billions of people over the next few decades. “Mitigation via emissions reductions helps no one for decades to come, whereas people are helped in the near term as well as in the future by locally designed and implemented adaptation,” Curry explains. Rehabilitating natural variability inevitably requires adaptation, unless the threat of extreme weather is used merely as a rhetorical device to secure support for emissions cuts. In all the analyses that Curry has undertaken of regional scenarios of extreme weather events over the next three decades, “variations associated with natural climate variability substantially exceed any expected change from global warming.”
Curry points to practical examples of successful adaptation. In 1970, up to a half-million Bangladeshis lost their lives because of a tropical cyclone. In 2007, a similar-magnitude cyclone cost 3,000 lives. The enormously reduced toll on human lives is thanks to the building of cyclone shelters, early warning systems, and mangrove restoration. A heat action plan that Curry helped devise for Ahmedabad, one of India’s hottest cities, involved mapping high-risk hot spots, providing more access to drinking-water stations, and more green spaces.
Curry contrasts the doctrine of sustainability, which aims to put a dynamic world into a stationary balance, with resilience, which looks for ways to manage weather risk in a continually imbalanced world. Superstorm Sandy in 2012 hit New York hardest where it had been most recently redeveloped. Lower Manhattan had been rebuilt to be sustainable, not resilient. Blaming the destruction caused by extreme weather events on climate change gives politicians a free pass. They can blame the horrifying wildfires on Maui this summer on climate change, but responsibility for the lack of preparedness and consequential loss of life lies squarely on the negligence of state and local officials.
The slow pace of warming and sea-level rise over the past century has allowed time for adaptation, Curry argues. Ten years ago, the extreme RCP 8.5 emissions scenario was regarded as the business-as-usual trajectory. Since then, RCP 8.5 has been viewed as increasingly implausible, and a trajectory closer RCP 4.5 has taken its place, implying a 2°C–3°C end-of-century warming. In the past, the prospect of such an outcome would have been regarded as a policy success, Curry says. She is rightly cynical that as the lower emissions and warming trajectories gained acceptance, the goalposts were moved by the IPCC in 2018 and the target lowered to 1.5°C, which is how we wound up with net zero by 2050.
An alternative to the UN climate-change paradigm
Curry rejects the UN climate-policy paradigm and what she calls the “politics of climate scarcity” and the associated politics of energy and material scarcity, and she advises abandonment of arbitrary temperature targets. Instead, the focus should be on appraising specific regional risks and vulnerabilities and proactively developing responses to them that have greater benefits than costs, noting the importance of prosperity, as people are less exposed to weather and climate shocks if they are not poor.
The need to reduce carbon dioxide emissions is much less pressing than the IPCC and the UN contend because of the implausibility of extreme emissions scenarios such as RCP 8.5 and of high values for the climate sensitivity of carbon dioxide (the warming caused by a doubling of carbon dioxide in the atmosphere). Natural variability is likely to slow down the rate of warming over the next few decades, and further time can be bought by targeting greenhouse gases other than carbon dioxide, which account for up to 45% of human-caused warming.
Climate Uncertainty and Risk is more than a book. Curry has produced a single-author counter to the IPCC that offers a radical alternative to the UN paradigm of climate change that could well serve as a manual for a future Republican administration.
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