This document summarizes the views of Bjorn Lomborg, a Danish academic and environmental writer known for his skeptical stance on issues like global warming. It discusses Lomborg's key arguments from his book The Skeptical Environmentalist, including that the impacts of global warming are exaggerated and the costs of addressing it outweigh the benefits. Lomborg founded the Copenhagen Consensus to determine global development priorities in a cost-effective manner, concluding that issues like disease, malnutrition and education should take precedence over climate change mitigation. The document also examines Lomborg's perspectives on topics like carbon dioxide levels, climate modeling uncertainties, and the potential consequences of warming.

1. Environmental Decision Making
By Peter Akkies ’12
April 8, 2009

2. At a glance...
• Criticism of Lomborg
• Who’s Bjørn Lomborg?
• The Skeptical Environmentalist in a nutshell • Discount rates
• Lomborg on global warming • Risk and uncertainty
• Effect of CO2 on temperature • Optimistic assumptions
• Forcing comparison • Counter-arguments, counter-counter-
arguments and counter-counter-counter-
• Unrealistic scenarios arguments
• Consequences not as catastrophic • Sagoff’s views on the role of economics
• Copenhagen Consensus • Carrying capacity
• The costs and choosing what to do • Use of economics to minimize costs

3. Who’s Bjørn Lomborg?
• Danish author, academic and environmental writer; degree
in statistics
• Technological optimist
• Wrote The Skeptical Environmentalist and Cool It: The
Skeptical Environmentalist’s Guide to Global Warming
• Well-known figure in environmental economics
• Website “Lomborg errors”
• Danish ministry investigated his book for academic
honesty
• Huge scientific debate on his books
• Founder of Copenhagen Consensus (which was co-
sponsored by the Danish government and The Economist)

4. Four stages of denial (or, “pick the odd one out”)
Freeman Dyson:
Fred Singer: There’s Lord Monckton: Bjørn Lomborg:
(Before) It’s not us!
no warming! We’ll be fine! It’s too expensive!
(Now more sophisticated)

5. The Skeptical Environmentalist in a nutshell
• Technology will eradicate hunger
• Improvements in safety, education and leisure - not just GDP - are signs of prosperity
• There’s no widespread deforestation; higher economic growth will prevent deforestation
• Oil is not depleting as fast as others claim
• There’s plenty of water; there won’t be wars over water supplies, because they’d be too
expensive
• Air and water pollution decrease with GDP; we should aim for more GDP
• Global warming...

6. Lomborg on global warming
• It’s happening
• It’s manmade... kind of
• There’s too many uncertainties (aerosols and clouds!)
• Costs of preventing are much greater than benefits
• Climate change is inevitable; we should deal with it; instead we should focus
on e.g. AIDS and malaria
• NB: Lomborg’s book was published in 2001 and is based on the Third
Assessment Report

7. Lomborg on global warming
See video at
http://www.youtube.com/watch?v=Dtbn9zBfJSs

8. CO2 effect on temperature
• Effect of CO2 on temperature is unclear
• “Models [are] more noisy than the climate response”
• Less particles are emitted than in the IPCC models, leading to cooling
• Solar irradiance variations might be part of the cause
• We can’t model clouds properly
• Claude Henry (physicist and economist): “Uncertainty should not be inflated
and invoked as an alibi for inaction.”

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RADIATIVE FORCING COMPONENTS
The global mean radiative forcing of the climate system
for the year 2000, relative to 1750
3
Halocarbons
Radiative forcing (Watts per square metre)
N2O Aerosols
2
CH4
Black
carbon from
Warming
CO2 fossil
1 Tropospheric Aviation-induced
Mineral
fuel
Solar
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burning
Contrails Cirrus
0
Stratospheric Organic
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fossil indirect
only
fuel effect
burning
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High Medium Medium Low Very Very Very Very Very
Very
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Low Low Low Low Low
Low
Low Low
Level of Scientific Understanding
Figure SPM.2. Global average radiative forcing (RF) estimates and ranges in 2005 for anthropogenic carbon dioxide (CO2 ), methane
Figure 3: Many external factors force climate change.
(CH4 ), nitrous oxide (N2O) and other important agents and mechanisms, together with the typical geographical extent (spatial scale) of
These radiative forcings arise from changes in the atmospheric composition, alteration of surface reflectance by land use, andvariation in the output the forcing and the assessed level of scientific understanding (LOSU). The net anthropogenic radiative forcing and its range are also
shown. These require summing asymmetric uncertainty estimates from the component terms, and cannot be obtained by simple addition.
of the sun. Except for solar variation, some form of human activity is linked to each. The rectangular bars represent estimatesof the contributions of
IPCC 2001 IPCC 2007
Additional forcing factors not included here are considered to have a very low LOSU. Volcanic aerosols contribute an additional natural
these forcings − some of which yield warming, and some cooling. Forcing due to episodic volcanic events, which lead to a negative forcing lastin
g
forcing but are not included in this figure due to their episodic nature. The range for linear contrails does not include other possible effects
only for a few years, is not shown. The indirect effect of aerosols shown is their effect on the size and number of cloud dropl ts. A second indirect
e
of aviation on cloudiness. {2.9, Figure 2.20}
effect of aerosols on clouds, namely their effect on cloud lifetime, which would also lead to a negative forcing, is not shown.Effects of aviation on
greenhouse gases are included in the individual bars. The vertical line about the rectangular bars indicates a range of estimat s, guided by the
e
Halocarbon radiative forcing has been recently assessed in detail in IPCC’s Special Report on Safeguarding the Ozone Layer and the Global Climate System (2005).
8
spread in the published values of the forcings and physical understanding. Some of the forcings possess a much greater degree o certainty than
f
others. A vertical line without a rectangular bar denotes a forcing for which no best estimate can be given owing to large uncerainties. The overall
t
4
level of scientific understanding for each forcing varies considerably, as noted. Some of the radiative forcing agents are wellmixed over the globe,
such as CO2, thereby perturbing the global heat balance. Others represent perturbations with stronger regional signatures because of theirspatial
distribution, such as aerosols. For this and other reasons, a simple sum of the positive and negative bars cannot be expected o yield the net effect
t
on the climate system. The simulations of this assessment report (for example, Figure 5) indicate that the estimated net effectof these perturbations
is to have warmed the global climate since 1750. [Based upon Chapter 6, Figure 6.6]

10. IPCC scenarios are unrealistic
• There are 40 scenarios! How can they all be realistic?
• (Bad) analogy: when icebergs impeded travel between North America and
Europe, we built jets to fly over the ocean.
• Rather than assume certain scenarios as likely, we should model them
• Dynamic Integrated Economic and Climate (DICE) model
• Pessimistic about technology improvements (e.g. solar energy efficiency)

11. Consequences not as catastrophic
• CO2 is a plant fertilizer
• “it is unreasonable to assume that a much richer world will make no
improvement in sea protection”
• More people die from cold spells than from heat spells
• We don’t know what El Niño will do and therefore don’t know about extreme
weather
• “it is not true that global warming has made us experience or will make us
experience great increases in hurricanes and storms”
• Same position as IPCC in 1996; now, the IPCC predicts more extreme
weather

12. Copenhagen Consensus
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13. The costs and choosing what to do
• Climate change adaptation and mitigation costs are huge, but far in the future
• Kyoto is insignificant
• Reply by Stephen Schneider: Lomborg assumes - and this is very unlikely
- that we will only have Kyoto and then nothing else
• DICE models better at incorporating all the costs

14. Discount rates
• In economics, benefits (costs) in the future are less (more) preferable to those today. (Would you
prefer that I give you a dollar today or next year?)
• Mathematically, this is accounted for by discounting the values--dividing by (1+r)^t where r is the
discount rate at t years into the future.
• Lomborg and the Copenhagen Consensus determine that mitigating climate change is ineffective
because it’s so far into the future.
• The benefits of mitigating global warming occur far in the future, so they get “squished” by the
compounded discount rate.
• The costs of mitigating global warming occur now.
• The net effect is that the costs exceed the benefits, according to Lomborg.
• Ramsey (1928), Pigou (1932) and Harrod (1948) have all suggested that ethically, future discount
rates should equal zero.
• But Cline (1992) and Anand and Sen (2000) point out that discount rates should be positive if we
expect future generations to be richer.
• Does it make sense to talk about discount rates if we’re facing global catastrophe?

15. Optimistic assumptions
• Lomborg: with increased GDP
comes increased technology to
solve the world’s problems
• SciAm: “Things improve because of
the efforts of environmentalists to
flag a particular problem, investigate
it and suggest policies to remedy it.”
• Improvements in renewable energy
will crowd fossil fuels off the market
• Schneider: most economists
agree that is unlikely

16. Counter-arguments,
counter-counter-arguments
and counter-counter-counter arguments
• SciAm article vs. Lomborg’s rebuttal vs. SciAm author’s rebuttals
• BBC veteran environmental reporter Alan Kirby: “What really riles me about his book is
that it is so damnably reasonable. ... The real world is messier, more unpredictable -
and more impatient.”
• Grist, online popular magazine: “As Lomborg notes, ‘We will never have enough
money,’ and therefore, ‘Prioritization is absolutely essential.’ Why, then, does he weigh
the environment only against hospitals and childcare, rather than against, say, industry
subsidies and defense spending?”
• New York Law School Law Review reviewed commentaries on Lomborg’s book and
found that both criticism and defense was highly ideological
• Support from: The Economist, (partially) The New York Times and The Washington
Post

17. Sagoff on ecological economists
• Mainstream economists: no limits to growth
• Ecological economist: limits to growth
• “[the goal of preservation of nature] is too important
to leave to economists -- including ecological
economists”
• Ecological economists’ distinction between growth
and development is false

18. Carrying capacity
• Second law of thermodynamics: the entropy of the world is always increasing
• Sagoff: the second law is not applicable, because we can get energy from
extraterrestrial sources such as the Sun
• He points out that the size of the economy (in GDP terms) is
• Unrelated to physical size and therefore
• Economies can grow while reducing demands on the environment
• Net primary production is a flawed measure and does not limit economic
growth

19. The use of economics in environmental policy
• Sagoff: economists should not be in the business of valuation, but in the
business of improving institutional arrangements
• Reform of public land grazing to allow environmentalists to buy fragile land
• Cap-and-trade schemes
• Useful concepts
• “Knee of the curve” method
• Emissions from power plant near Grand Canyon
• Intel’s chip plants and the product-to-emission ratio
• Economists should do cost-effectiveness analysis, not cost-benefit analysis

20. Discussion and/or questions?