Bjorn Lomborg’s New Paper ‘Appears To Have No Basis In Fact’

Widely debunked confusionist Bjorn Lomborg has twisted the world’s climate pledges beyond recognition to make it seem as if the upcoming Paris climate talks will have no impact on future warming.

His purpose, beyond sowing confusion, is to justify this claim in his press release “Lomborg shows Paris commitments will reduce temperatures by just 0.05°C in 2100.” In reality, China’s commitment alone — which Lomborg explicitly ignores — reduces projected future temperatures by 0.4°C in 2100!

Climate Interactive has previously documented that the Paris pledges, the intended nationally determined contributions (INDCs), would reduce projected future temperatures by about 1°C — and buy us another decade close to the 2°C path (see chart above).

The experts at Climate Interactive looked at Lomborg’s new paper and concluded that his collection of assumptions “appears to have no basis in fact” and that his “optimistic” cases “are, in fact, deeply pessimistic.” John Sterman, Professor at MIT’s Sloan School of Management and Director of MIT’s System Dynamics Group, told Climate Progress:

Dr. Lomborg sets out to show that the INDCs are useless. To do so he grossly misrepresents the pledges. He constructs an incomplete accounting of the pledges that omits the pledges of many nations, ignores China’s pledge to cap its emissions by 2030, and assumes that the [European Union countries] abandon their commitment to emissions reductions as soon as their pledges are fulfilled.”

Climate Progress readers know Lomborg well from such stories as “Climate Scientists Debunk Lomborg,” “Lomborg Is Part Of The Koch Network” and “Lomborg Urges Climate Inaction With Misleading Stats In Murdoch’s Wall Street Journal.”


Anyone thinking of citing Lomborg’s latest nonsense should be aware his analysis rests on several assumptions that range from factually incorrect to intellectually indefensible:

  • Lomborg simply decides he will ignore the Chinese pledge to peak emissions by 2030 or sooner — an assumption so unjustifiable it should have rendered the entire paper unpublishable.
  • Lomborg appears to ignore many of the major developing nation pledges, but offers no reason why.
  • Lomborg assumes that after the European Union meets its 2030 climate pledge — a 40 percent reduction versus 1990 levels — the EU will immediately reverse what will have been four decades of policy-driven reductions and return to rapid emissions growth.

Let’s focus on Lomborg’s non-explanation for ignoring China’s linchpin climate pledge. China’s INDC states, “China has nationally determined its actions by 2030 as follows: To achieve the peaking of carbon dioxide emissions around 2030 and making best efforts to peak early.”

China famously made that commitment 12 months ago in a joint statement with the United States. As we reported this summer, every indication is China will in fact peak by 2025.

But Lomborg’s study models a steady rise in CO2 emissions for decades beyond 2030, as this figure shows:

This figure from Lomborg’s paper on the INDCs’ impact on future warming shows that Lomborg has ignored China’s INDC, which has China peaking in CO2 emissions by 2030.
This figure from Lomborg’s paper on the INDCs’ impact on future warming shows that Lomborg has ignored China’s INDC, which has China peaking in CO2 emissions by 2030.

How can he publish an analysis on the impact of the Paris INDCs that ignores the single most important one? Here’s his explanation — a truly logic-defying paragraph:

China’s INDC has made two significant promises (China INDC, 2015). One is a promise to peak its emissions around 2030. That is a promise, which will only start having a policy impact around and after 2030, which falls outside the 2030 time limit for policy purposes set in this article.

What Lomborg is saying is that in modeling the impact through 2100 of the world’s various INDCs, he is not going to model any policy commitments that extend past 2030. Why? Because. [In fact, the 2030 peak has, according to many experts, a policy impact by 2020 — a peak in coal use.]


Lomborg’s dismissal of China’s INDC is so intellectually indefensible, so transparently designed to underpin utterly untrue conclusions and soundbites by Lomborg, it not only invalidates the entire analysis — it calls into question the credibility of the entire journal, Global Policy and its peer-review process.

Indeed, the abstract could not possibly be more intentionally misleading when it states:

All climate policies by the U.S., China, the EU and the rest of the world, implemented from the early 2000s and sustained through the century will likely reduce global temperature rise about 0.17°C in 2100.

It is hard to call that anything other than a lie. This study does not model China’s INDC policies “sustained through the century.” The piece should be retracted on this basis alone.

According to Climate Interactive, China’s INDC, by itself, reduces future warming some 0.4°C in 2100 — which is more than double what Lomborg asserts all of the Paris INDCs accomplish!

Besides ignoring China’s INDC, and assuming the EU immediately reverses decades of climate policies starting in the year 2031, here are other things Lomborg assumed to get his indefensible result, according to Climate Interactive:

  • Dr. Lomborg’s estimate of the emissions reductions from the countries representing the majority of the world’s emissions, the “Rest of World” (countries other than China, US, and EU, comprising 53 percent of total greenhouse gas emissions in 2015) appears to have no basis in fact. The paper cites “emissions reduction of 1.5Gt from all other countries” without supplying the method of his estimation.
  • Dr. Lomborg’s estimate of the impact from “Rest of World” pledges (1.5 Gt) significantly underestimates emissions reductions pledged to date. We estimate over three times as much reduction from his “ROW” area — 5.9 Gt per year reduction below the global reference scenario by 2030″, compared to his 1.5 Gt per year.
  • Dr. Lomborg’s estimate seems not to account for country pledges from the developed world other than the US and EU: for example, Canada, Japan, Australia, and South Korea have all pledged to reduce their absolute emissions. His estimate also appears to ignore notable pledges from the developing world: for example, Mexico (25% below BAU by 2030), Brazil (45% below BAU by 2030), and South Africa (peak in 2020–2025 followed by decline).

Climate Interactive’s Andrew Jones says, “Honest analyses by a number of independent scientific groups show that the current INDCs, if fully implemented, would lower expected warming from a BAU level of about 4.5°C to 3.5°C if there is no action beyond the current pledges, and to 2.7°C is there is greater ambition.” Jones adds, “While deeper cuts are needed to achieve the 2°C limit that the nations of the world have agreed to, the INDCs do represent significant progress.”

For a detailed analysis of what the Paris pledges actually will and will not achieve, see here.

Any concerns about Lomborg’s article can be tweeted to the journal and its editors at

This post has been updated.