Bjørn Lomborg, a Danish political scientist and president of the Copenhagen Consensus Center, accepts the basic science of human-caused climate change but argues that aggressive emission-reduction policies are among the least cost-effective ways to improve human welfare. His central claim is not that climate change is fake but that the money spent trying to prevent it would do far more good if redirected toward problems like disease, malnutrition, and trade reform. That framing has made him one of the most cited and most contested voices in climate policy for over two decades, drawing fierce criticism from climate scientists, economists, and environmental organizations who say his analysis cherry-picks data and undervalues future climate risks.
The Core Argument
Lomborg’s position can sound deceptively moderate. He does not dispute that the planet is warming or that human emissions of greenhouse gases are a primary driver. What he disputes is whether the world’s response should center on rapid decarbonization. In his telling, the economic costs of cutting emissions deeply and quickly are enormous, while the benefits of those cuts, measured in avoided warming, are modest relative to the price tag. He argues that the same money, invested instead in fighting infectious disease, improving nutrition, or expanding free trade, would save far more lives far sooner.
This argument rests on cost-benefit analysis as the primary decision-making tool for global policy. If you accept the premise that every dollar should be measured by how much measurable human welfare it buys in the near term, Lomborg’s math can look persuasive. Much of the scientific and policy backlash against him comes from people who reject that premise, or who argue that his version of cost-benefit analysis is built on assumptions that dramatically undercount what climate change will actually cost.
The Copenhagen Consensus
Lomborg’s highest-profile institutional project has been the Copenhagen Consensus, a series of exercises in which panels of economists, including several Nobel laureates, were asked to rank global challenges by where a hypothetical budget would do the most good. In its first round in 2004, the panel was given a thought experiment: if the world had $50 billion to spend, where should it go? The group compiled a list of ten challenges, including climate change, communicable diseases, conflicts and arms proliferation, education, financial instability, governance and corruption, malnutrition and hunger, migration, sanitation, and trade barriers. The panel ranked these by estimated return on investment.
Climate change came in last. The panel’s top recommendations were controlling HIV/AIDS, controlling malaria, addressing micronutrient deficiencies, and liberalizing trade. The stated rationale was that the costs of climate mitigation would outweigh the benefits, while interventions in health and nutrition offered dramatically higher returns per dollar spent.1Journal of Environmental Law. Benefits and Costs of the Environment: Copenhagen Consensus 2008 A second round in 2008 produced broadly similar results, again placing climate mitigation near the bottom of priorities.
The exercise was influential, but the framing itself drew criticism. Asking economists to rank problems by short-term cost-effectiveness on a fixed budget creates a structure that inherently favors cheap, fast interventions like distributing bed nets or vitamin supplements over slow, expensive infrastructure changes like decarbonizing an energy system. Critics pointed out that this is not actually how global budgets work. Spending on malaria prevention and spending on clean energy are not drawn from the same pool of money, and there is no reason a government or international body has to choose one over the other. The either-or framing, critics argued, was itself a rhetorical move that made climate action look like it came at the expense of saving children from malaria.
Lomborg on the Paris Agreement
One of Lomborg’s most specific and frequently cited claims concerns the Paris Agreement signed in 2015. Using the MAGICC climate model, a standard tool in climate science, he published an analysis estimating the temperature reduction that would result from the emission-cut pledges made by major countries if those pledges were honored through the end of the century. His findings painted an underwhelming picture. The U.S. Clean Power Plan would reduce warming by about 0.013°C by 2100. The full U.S. pledge for the Paris conference would reduce it by 0.031°C. The EU’s initial 20-20 policy would achieve about 0.026°C of reduction, while China’s pledge would achieve roughly 0.048°C. Adding up all climate policies from the U.S., China, the EU, and the rest of the world, implemented from the early 2000s through 2030 and sustained for the rest of the century, the total reduction in global temperature rise would be about 0.17°C by 2100.2Global Policy. Impact of Current Climate Proposals
The implication Lomborg drew was that Paris was an enormously expensive way to achieve a tiny amount of cooling, and that the trillions of dollars involved would be better spent elsewhere. The analysis was published in a peer-reviewed journal and the model he used is a legitimate and widely used tool. But several aspects of the framing have been challenged. Climate scientists and policy analysts have pointed out that Paris was never designed to solve warming in a single round of pledges. The agreement’s structure is built around a “ratchet mechanism,” where countries are expected to strengthen their targets every five years. Evaluating the first round of pledges as though they represent the permanent ceiling of ambition, critics argued, is like judging a marathon runner’s speed based on the first hundred meters.
Additionally, Lomborg’s calculation assumed that no new policies would be adopted after 2030, which is inconsistent with how the agreement was designed to function. Climate economists have noted that the value of Paris lies partly in creating a framework for escalating action, not in the first-round numbers alone. Whether you find Lomborg’s framing reasonable depends on how much faith you place in future rounds of ratcheting versus how much weight you give to what has actually been committed so far.
The Scientific Dishonesty Ruling
Lomborg’s first book, “The Skeptical Environmentalist,” published in English in 2001, argued that many environmental problems were overstated by activists and poorly supported by data. The book ignited a major controversy. Journals including Nature and Scientific American published sharp critiques accusing him of selectively using data and misunderstanding complex scientific issues. The backlash eventually led to a formal complaint filed with the Danish Committees on Scientific Dishonesty (DCSD), a government body that investigates research misconduct.
In January 2003, the DCSD ruled that the book was “systematically misleading” and represented “objectively dishonest” use of data, though it cleared Lomborg of acting with deliberate intent or gross negligence.3PubMed Central. Environmentalist accused of scientific dishonesty The distinction is meaningful: the committee found that the patterns of selective data use were serious enough to constitute dishonesty in the objective handling of evidence, but it did not conclude that Lomborg set out to deceive. Lomborg appealed, and the Danish Ministry of Science later sent the case back to the DCSD for reconsideration, criticizing the committee’s ruling as insufficiently detailed in its reasoning. The DCSD ultimately decided not to reopen the case, leaving the original ruling in a kind of procedural limbo.
Lomborg and his supporters have pointed to the appeal outcome as a vindication. His critics have pointed to the original ruling’s language as confirmation of what scientists had been saying since the book’s release. Either way, the episode established a pattern that has followed Lomborg’s career: he publishes claims using real data and recognized models, but the way he frames, selects, and contextualizes that data becomes the central point of contention.
Where the Numbers Get Contested
A recurring theme in critiques of Lomborg’s work is the charge that he selectively emphasizes findings that make climate impacts look manageable while downplaying or ignoring findings that point in the opposite direction. One example involves the relationship between temperature and mortality. Lomborg has frequently argued that cold kills far more people than heat, and that warming could, on net, save lives by reducing cold-related deaths.
That claim has a grain of truth in present-day data: in many parts of the world, cold-related mortality currently exceeds heat-related mortality. But research examining what happens as warming progresses tells a different story. A large modeling study covering 854 European cities projected that under continued warming with no adaptation to heat, the increase in heat-related deaths consistently exceeds any decrease in cold-related deaths across all considered climate scenarios. Under a scenario with relatively high emissions and low adaptation, the study estimated a net increase in climate-related deaths of about 50%, amounting to more than two million cumulative climate-change-related deaths in Europe between 2015 and 2099. Even under scenarios where populations adapt substantially to heat, a 50% reduction in heat vulnerability was still not enough to reverse the trend under high-emission conditions.4PubMed Central. Estimating future heat-related and cold-related mortality under climate change, demographic and adaptation scenarios in 854 European cities
This matters because the “cold kills more than heat” talking point takes a snapshot of today’s mortality data and projects it forward as though the ratio stays constant. Climate research increasingly shows it does not. As warming accelerates, the balance shifts toward net harm, particularly in southern and central Europe, parts of South and Southeast Asia, and tropical regions where populations already live near the upper limits of human heat tolerance.
The Discount Rate Question
Much of the disagreement over Lomborg’s cost-benefit analysis comes down to a technical choice that has enormous consequences: how much you discount future costs and benefits. When economists compare spending money today versus preventing damage decades from now, they apply a “discount rate” that makes future costs worth less in today’s terms. A high discount rate means future climate damages barely register against present-day spending. A low discount rate means those future damages loom large and justify aggressive spending today.
Lomborg’s analyses have generally used relatively high discount rates, consistent with market rates of return on investment. This is a defensible choice within mainstream economics, but it is not the only defensible choice, and it produces dramatically different conclusions than the alternative. When the economist Nicholas Stern published his landmark 2006 review of climate economics using a near-zero discount rate, he concluded that the costs of inaction on climate change dwarfed the costs of aggressive mitigation. The two frameworks, Lomborg’s and Stern’s, use many of the same underlying data but reach opposite policy conclusions, almost entirely because of this one assumption about how to value the future.
Critics of Lomborg’s approach argue that applying a high discount rate to climate change is ethically questionable because it effectively says that harm to people in 2080 matters much less than harm to people in 2025. Some economists have gone further, arguing that Lomborg’s work exemplifies a broader pattern in which economic ideology is dressed up as objective analysis. One academic critique accused “The Skeptical Environmentalist” of employing several techniques of ideological distortion, including suppressing relevant information, repeating false concepts, applying theory outside its domain of relevance, and casting ungrounded suspicion on the motives of environmentalists.5Global Environment. Economic Ideology about the Environment. From Adam Smith to Bjørn Lomborg
Lomborg’s defenders counter that a low discount rate is paternalistic, that it undervalues the ability of future societies to adapt with better technology and greater wealth, and that present-day poverty kills people right now in ways that can be measured and addressed. The debate over discount rates is ultimately a debate about values masquerading as a debate about math, and neither side has a monopoly on defensible reasoning.
Adaptation as the Preferred Strategy
If Lomborg’s position on mitigation is skeptical, his stance on adaptation is considerably more enthusiastic. He has consistently argued that investing in adaptation measures, things like flood defenses, drought-resistant crops, better urban planning, and heat-warning systems, delivers far more bang for the buck than trying to reduce emissions. The logic is straightforward: adaptation targets specific, measurable harms and produces benefits in the near term, while mitigation is expensive, slow, and requires global coordination that rarely materializes.
There is genuine substance to this argument. Adaptation spending does tend to have high returns, and many climate-vulnerable communities need better infrastructure regardless of what happens to global emissions. But most climate economists view adaptation and mitigation as complements, not substitutes. Adaptation works well for moderate warming but becomes increasingly difficult and eventually impossible at higher temperature levels. You can build a sea wall for a half-meter of sea-level rise. You cannot build a sea wall for three meters of sea-level rise in a megacity with ten million people and a sinking coastline. Framing adaptation as an alternative to mitigation, rather than as a necessary companion, risks implying that societies can engineer their way out of any level of warming, an assumption that the physical sciences do not support.
Lomborg has also promoted investment in clean-energy research and development, arguing that making green energy cheaper is a better path than taxing or regulating fossil fuels out of existence. He has pointed to innovation-driven cost declines in solar power as evidence that technology, not policy mandates, is the real lever. This is a more nuanced position than he is sometimes credited with, and it has some overlap with mainstream climate economics that emphasizes the importance of innovation. The disagreement is mainly about timing and emphasis: whether R&D investment alone can drive decarbonization fast enough to matter, or whether regulation and carbon pricing are necessary to accelerate the transition while innovation catches up.
Why Lomborg’s Influence Persists
Lomborg occupies an unusual niche. He is not a climate denier, and his work is published in peer-reviewed venues, which makes him harder to dismiss than figures who reject the basic physics of greenhouse gases. At the same time, his conclusions consistently align with the preferences of industries and political actors who oppose emission-reduction policies, which has made him a favorite citation in op-eds and policy briefs arguing against climate regulation. Environmental groups and many climate scientists view him as providing intellectual cover for delay, dressing up inaction in the language of rational prioritization.
His persistence in public debate says something about the state of climate communication. Lomborg’s arguments resonate partly because they acknowledge real trade-offs. Global poverty is devastating. Health interventions in low-income countries do offer extraordinary returns on investment. And climate policy does involve spending large sums of money on outcomes that are uncertain, distant, and distributed unevenly across the globe. A public that is skeptical of large government expenditures and worried about near-term economic pain finds Lomborg’s framing intuitively appealing. The challenge for climate advocates has been that “this is complicated and expensive but necessary” is a harder sell than “spend the money where it helps most right now,” even when the latter framing rests on assumptions that most climate economists consider incomplete.
What Lomborg’s Framework Leaves Out
The most fundamental critique of Lomborg’s approach is not that any single number he cites is fabricated, but that his framework systematically excludes categories of climate risk that do not lend themselves to tidy cost-benefit calculations. Tipping points are a prime example. Climate science has identified several potential thresholds, the collapse of major ice sheets, the dieback of the Amazon rainforest, the disruption of Atlantic Ocean circulation, where crossing a temperature boundary triggers self-reinforcing warming that cannot be reversed on human timescales. These events are difficult to assign probabilities to, and their costs are nearly impossible to monetize in advance. A cost-benefit framework that requires precise dollar figures for every outcome will tend to underweight these risks, not because they are small but because they are hard to quantify.
Biodiversity loss presents a similar problem. Ecosystems provide services, pollination, water filtration, carbon storage, coastal protection, that underpin economies in ways that standard economic models capture poorly. Lomborg’s framework acknowledges direct, measurable economic impacts of climate change but has little room for the cascading, nonlinear effects that ecologists warn about. When an ecosystem collapses, the economic consequences can be sudden and enormous, but predicting exactly when and where that collapse will happen is beyond current modeling capability. A framework that only counts what it can confidently price will always undercount ecological risk.
There is also the question of irreversibility. Many of the health and development investments Lomborg champions are genuinely valuable, but they are also reversible in a sense that climate change is not. If you underfund malaria prevention this decade, you can scale it up next decade and catch up. If you underfund emissions reduction this decade and pass a tipping point, there is no catching up. The asymmetry between reversible short-term harms and irreversible long-term harms is something that standard cost-benefit analysis handles poorly, and it is central to why many climate economists argue that the precautionary case for aggressive mitigation is stronger than Lomborg’s numbers suggest.