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DNATEUR
Lese Haroun
Conclusion
NAEC
• My arguments are independent of my well-known criticisms of Neoclassical economics
• Other economists have rightly criticized Nordhaus & IAMs before:
DeCanio 2003: “The result of this modelling failure has been a bias against bold
and timely action.. and pervasive paralysis in the political debate" (p. 153)
• Pindyck 2017: “integrated assessment models (IAMS) have crucial flaws that
make them close to useless as tools for policy analysis...
• IAM-based analyses of climate policy create a perception of knowledge and
precision that is illusory and can fool policymakers into thinking that the
forecasts the models generate have some kind of scientific legitimacy." (p. 100)
• No Neoclassical should defend IAMS simply because the authors are Neoclassical,
given the appallingly unrealistic assumptions on which their models are based
• This is not an academic game
• Human society should not be sacrificed on the altar of the patently absurd
"simplifying assumptions" of economists
DNATEUR
Lese Haroun
結論
NAEC
- 私の議論は、新古典派経済学に対する私のよく知られた批判とは無関係である。
- 他の経済学者は以前からノードハウスとIAMを正当に批判している。
DeCanio 2003: 「このモデル化の失敗の結果として、大胆でタイムリーな行動への偏見が生まれた。
とタイムリーな行動に偏っており、政治的議論には麻痺が蔓延している」(p. 153)
- Pindyck 2017年 「統合評価モデル（IAMS）には、ツールとしてはほとんど役に立たないような重大な欠陥があります。
政策分析のためのツールとしてはほとんど役に立たない...。
- IAMに基づく気候政策の分析は、知識と精度の認識を作り出すが、それは幻想であり
IAMに基づく気候政策の分析は、幻想的な知識と精度の認識をもたらし、政策立案者を騙して
IAMに基づく気候政策の分析は、幻想的な知識と精度の認識をもたらし、政策立案者を欺いて、モデルが生成する予測がある種の科学的正当性を持っていると思わせてしまう。(p. 100)
- 新古典主義者は、著者が新古典主義者であるという理由だけでIAMSを擁護すべきではない。
IAMSのモデルが、恐ろしく非現実的な仮定に基づいていることを考えれば。
- これは学術的なゲームではない
- 明らかに不合理な経済学者の「仮定の単純化」のために、人間社会を犠牲にしてはならない。
経済学者の「単純化された仮定」のために犠牲になってはならない
00:05
we all know that the Nobel Prize is
00:07
about to be awarded again last year was
00:09
awarded to two people one of whom was
00:11
William Nordhaus for the integrating
00:13
climate change and the long-run
00:14
macroeconomic analysis and this is a key
00:17
slide from the lecture that Nordhaus
00:20
gave as part of receiving the Nobel
00:22
Prize or a number of trajectories
00:24
identified there for temperature between
00:27
now and 2050 and he described one of
00:30
those as optimal with a four degree
00:34
increase in temperature above
00:35
pre-industrial levels by 21:40 optimal
00:39
four degrees greater than pre-industrial
00:42
levels now in what way could you regard
00:49
a four degree increase in temperature
00:50
over pre-industrial levels is optimal
00:53
well the basic logic was it minimizes
00:56
the cost of a basement and the cost of
00:58
climate change together if you said we
01:01
did Noah Bateman whatsoever in other
01:02
words we simply let the climate proceed
01:05
as it is with the level of carbon
01:07
dioxide and other pollutants were
01:09
popping into the atmosphere then the
01:11
temperature greater than six degrees
01:12
above pre-industrial levels and the net
01:16
present value damage of that would be 23
01:19
trillion slightly more than the u.s.
01:20
economy the cost of abatement therefore
01:25
is zero now if we go for optimal
01:28
abatement which would reduce temperature
01:30
to minimize it to a four degree increase
01:32
or about four degrees over
01:33
pre-industrial the damages would be
01:35
fifteen trillion less than the size of
01:37
the US economy now and cost of abatement
01:40
three those are the calculations there
01:46
now six months before he gave that talk
01:49
a genuine climate scientist William will
01:53
Stefan described the likelihood of a 5-4
01:57
degree increase in temperature this way
01:59
the tropics are in uninhabitable and the
02:03
punchline down the bottom there the
02:05
maximum carrying capacity of the planet
02:06
about 1 billion humans versus 7 and a
02:10
half billion now now how on earth can
02:14
you square those two
02:16
visions of the future what I believed
02:19
before I started reading these papers in
02:21
detail was that economists were applying
02:23
a very high discount rate to the same
02:26
estimates of damage
02:27
I found that wasn't the case they were
02:30
affecting making up their own estimates
02:32
using a range of methods the most absurd
02:35
of which is the following they were
02:38
using today's variation in GDP and
02:41
temperature across the planet and
02:43
believing they could use that to
02:45
estimate the impact of climate change
02:47
over time this is when one of the key
02:50
papers aggregating this so-called
02:52
empirical research they assumed the
02:54
observed variation of economic activity
02:56
with climate over space holds over time
02:58
as well
02:59
sounds very clever it's incredibly
03:01
stupid what they did was they took data
03:05
on GDP and temperature today across the
03:09
globe mainly across America and they
03:11
found a weak quadratic relationship
03:14
between temperature and GDP they then
03:17
assumed that same relationship would
03:19
apply as we massively increase the
03:22
amount of energy retained from the from
03:24
the Sun by adding to greenhouse gases
03:27
they called it the statistical approach
03:29
to the number of different labels they
03:30
used for it this is one of the first
03:32
papers to do it not the only by far you
03:34
said the climate response functions were
03:36
quadratic countries that are currently
03:40
cooler are going to benefit country that
03:43
are currently warmer will be harmed and
03:45
the cross-sectional putting all the data
03:48
together they presumed that an increase
03:50
in temperature I think three degrees in
03:51
this case would bring benefits of a
03:55
hundred and forty five billion dollars
03:56
per year now that became a data point
04:02
that Nordhaus used to estimate his
04:05
damage function which is simply a
04:07
quadratic it's the temperature
04:09
difference over pre-industrial level
04:12
squared multiplied by a coefficient of
04:14
course he had to work out what that
04:15
coefficient was so using symbol that
04:20
this sort of data and equally flawed
04:21
data there's mendelssohn's data point
04:23
whether with a point one percent
04:24
increase in GDP could achieve a two
04:26
point five degree increase in global
04:28
temperature
04:29
or others that use the same same idea
04:32
that's not houses own contribution in 94
04:35
assuming the same relationship and the
04:40
coefficient has been just in the most
04:42
recent papers reduced it yet again his
04:45
coefficient for that quadratic is point
04:47
zero zero two two seven meaning that a
04:50
one degree increase in temperature over
04:51
pre-industrial the Austrians will cause
04:53
a point two to seven percent fall in
04:56
global GDP this is before discounting by
04:59
the way this is not discounted this is
05:01
simply what they say the actual damage
05:03
will be two degrees will cause less than
05:06
a wonder but one percent fall four
05:09
degrees will just cause a three point
05:10
six degree percent fall even ten degrees
05:13
would just reduce GDP by twenty three
05:16
percent over what it would have been in
05:19
the complete absence of global warming
05:23
now these conclusions are only valid if
05:27
and only if the assumption that the
05:29
variation we see across space today will
05:32
be the same over time with the
05:34
incredible increase in the amount of
05:36
energy that would be retaining in the
05:38
biosphere courtesy of additional
05:40
greenhouse gases and I got involved in a
05:43
fairly acrimonious exchange with one of
05:46
the economists who has been writing
05:47
these IPCC reports the some years now
05:50
William told Todd Richard toll pardon me
05:52
and as part of that he said this is one
05:55
of his traits
05:55
ten degrees Kelvin is less than the grid
05:58
temperature difference between Alaska
05:59
and Maryland blah blah blah climate is
06:02
not a primary driver of income this is
06:04
one of the people drafting the IPCC
06:06
reports now a meteorologist intervened
06:09
in its discussion and said that a global
06:11
climate ten degrees warmer than to the
06:13
present is not remotely the same thing
06:15
as taking the current climate and simply
06:18
adding 10 degrees everywhere tolls
06:21
response to that was to say that's not
06:24
the point we see people thrive in very
06:25
different climates climate determinism
06:28
therefore has no empirical support and
06:32
he finally said if you can't show that
06:33
it heads over space why can you say that
06:35
it holds over time
06:40
now what they've done is that takin GDP
06:43
in two places normally in America and
06:45
compared them while the level of energy
06:48
in the biosphere remains constant you're
06:51
not looking at change over time okay
06:53
what global warming will do is
06:55
dramatically increase the amount of
06:57
energy in the biosphere completely
06:59
disrupting the existing climate
07:02
disrupting human life as well as a
07:04
result of that you get no information
07:06
whatsoever about the impact of global
07:09
warming by looking at local temperature
07:11
to GDP relationships and I want to give
07:13
a little simple illustration of this
07:15
just for the sake of exposition let's
07:18
assume and this is simply for the sake
07:20
of exposition I don't believe it okay
07:22
let's assume temperature is a linear sum
07:24
of the global temperature caused by our
07:26
location in the Goldilocks zone around
07:28
our star plus local deviation caused by
07:32
whereabouts you are on that the surface
07:34
of the planet and assume that there's a
07:36
linear relationship between GDP and
07:38
temperature as well so the hypothesis
07:40
they had was something like this GDP per
07:42
capita is a function of two temperatures
07:44
the global temperature given by the
07:46
Goldilocks location then and and by
07:49
greenhouse gases pre-industrial levels
07:53
plus local deviation to get alpha one
07:55
climbs global temperature plus alpha two
07:57
times local temperature and then you get
08:00
well let's look at that for Florida so
08:01
the local deviation in America at seven
08:04
degrees higher than the average for
08:05
America the decatur it's ten degrees
08:08
below and then you do a calculation you
08:10
subtract the two you get a relationship
08:13
saying the difference between the two is
08:14
17 times the value of your coefficient
08:17
for the local temperature variation
08:19
you've canceled out your global
08:22
temperature variation you then can solve
08:24
for alpha to get an estimate of it you
08:27
have no information on alpha one so are
08:29
you assume alpha one equals alpha two
08:32
that is outrageously stupid and not just
08:36
stupid in some academic exercise this is
08:39
threatening the existence of human
08:40
society if anybody's going to bring
08:43
capitalism undone it's going to be the
08:45
Economist who wrote this research
08:48
now it's like having and I want to give
08:50
a graphic illustration what this is like
08:52
this is like having north-south data on
08:55
a mountain not having any east-west but
08:58
because it's flat you tell the hikers
09:01
that walking east-west is safe because
09:03
Northwest is flat and you're on the edge
09:06
of El Capitan that's about as smart as
09:10
what economists have done in this case
09:12
and this fatally unrealistic climate
09:15
data I'm putting in inverted commas was
09:18
calibrated to equally unrealistic damage
09:20
functions and it's the difficulty as
09:24
we're trying to graph something we
09:25
haven't experienced so I want to say we
09:28
can actually use their models and use
09:30
their assumptions which is quadratic
09:31
damage functions to look at things we
09:34
actually have experience because we have
09:36
experienced as a species lower
09:38
temperatures than today the last ice age
09:41
when you go backwards and look at the
09:43
temperature records you find the last
09:45
ice age was about 4 degrees lower below
09:49
that the average for 1951 to 1980 so
09:53
what was the planet like then and what
09:56
does not houses damage function predict
09:58
would be the impact on GDP if we were
10:01
facing global cooling rather than global
10:03
warming well 20,000 years ago it was 4
10:06
degrees cooler that's what the planet
10:08
looked like Nordhaus prediction that
10:12
would reduce GDP by 3.6 percent he
10:17
deserves to be laughed out not given a
10:19
Nobel Prize okay and yet this is the
10:22
basis of economists saying we don't need
10:24
to worry about it and assuring
10:25
politicians they don't need to worry
10:27
it's sheer nonsense again just to make
10:30
the obvious New York can be immediate it
10:32
would be one kilometer below ice that's
10:34
not going to affect GDP by more than 3.6
10:36
percent
10:37
you simply cannot extrapolate to that
10:39
world from our current data but that's
10:41
what they've been doing now why do they
10:45
ignore tipping points they talk about it
10:47
all the time but it never turns up in
10:48
their function certainly not in law
10:49
houses he's actually made it less
10:51
capable of handling tipping points his
10:53
most recent paper it's because you can't
10:55
do cost-benefit analysis when you have
10:57
discontinuities so the response of the
10:59
economists was let's ignore the tipping
11:02
and what the climate scientist is saying
11:04
and they're saying it much more politely
11:05
than me I hope they're going to join me
11:07
in being as rude as is necessary to get
11:09
through on this front they're saying
11:11
abandoned cost-benefit analysis stefan
11:14
published a joint paper with about 16
11:16
other climate scientists just recently
11:18
and they've said very mildly the
11:20
contemporary way of guiding development
11:22
founded on beliefs of gradual and
11:24
incremental change will not likely be
11:25
adequate to cope with this trajectory
11:27
well it certainly won't because they're
11:30
not even imagining that that trajectory
11:32
is what we actually face so my position
11:36
on having read this data reading the
11:38
IPCC reports we should remove economists
11:40
from the IPCC if not that we should at
11:44
least appoint non mainstream economists
11:46
who would not make such a stupid
11:48
assumption people like myself camp
11:52
adriano garret garage Rosselli there's a
11:55
number of people doing the unorthodox
11:56
work on that we would not agree to that
11:59
assumption and get climate scientists to
12:02
vet what's being done now what is
12:03
happening because we're not doing this
12:05
as climate change denier lists or what I
12:08
think a better called climate change
12:10
trivializes are using the IPCC to
12:13
justify trivializing I don't need to
12:15
introduce you on Lomborg to anybody here
12:17
and here a few statements by him
12:19
today's noble Lord shows optimal climate
12:21
solution is one is 3.5 degree
12:26
temperature increase he's quoting the
12:28
IPC again showing those damage function
12:31
points six degrees is likely to reduced
12:38
by six to twelve percent of GAAP and
12:42
he's quoting the IPCC is quoting
12:44
economists to make these statements and
12:47
he rubbishes the students getting
12:51
involved the I the extinction rebellion
12:53
and then he says you know in uric and
12:55
problem IPCC impacts smaller than most
12:58
other drivers let's take a good look at
13:00
this he actually is quoting the IPCC for
13:03
most economic sectors the impact of
13:04
climate change will be small relative to
13:07
the impact of other drivers include and
13:08
they have the including population
13:11
medium evidence high agreement
13:15
so the whole group of economists putting
13:17
this together have fallen into the same
13:19
group think of believing that ridiculous
13:22
assumption that data about temperature
13:25
and GDP today can be used to predict the
13:27
impact of climate change and you won't
13:29
be amazed to hear one of the authors is
13:31
lead authors of that particular document
13:36
we should be using data from the climate
13:39
scientists themselves including the work
13:41
that Stefan has done and others to
13:43
identify tipping points of course the
13:45
first of those tipping points is
13:46
probably already gone Arctic winter sea
13:49
ice and the Cascade that will cause will
13:52
mean we simply can't stay at the levels
13:55
of temperature that these economists
13:56
think is going to be benign we need
13:58
models that actually in which energy
14:00
plays a fundamental role now none of
14:03
them at neoclassical models none of the
14:04
post Keynesian models yet properly
14:06
include energy properly I'm starting to
14:08
do that work with Bruce le and Garrett
14:11
and when we feed that in we can get both
14:13
cyclic or economic behavior followed by
14:15
economic collapse in this particular
14:17
simple illustration of running out of
14:19
resources but simple and it's stylized
14:21
but it's already more realistic than
14:23
what Nordhaus have done because it
14:25
includes resource constraints that are
14:27
absent from the work being done by these
14:29
so-called climate economists so and now
14:32
you know i'm a critic of mainstream
14:33
economics that's no secret but my
14:36
criticisms here are not dependent upon
14:38
me rejecting things like the ramsay
14:40
growth model and so on i haven't even
14:42
got to the ramsay growth model yet it's
14:45
just the stupid assumptions they're
14:46
making no self-respecting neoclassical
14:49
economist should put forth what these
14:51
people are doing and several beforehand
14:53
before me have come out and said these
14:54
are crucial if these crucially flawed
14:56
next to useless they're worse than
14:58
useless
14:59
they've distracted us from the important
15:01
challenge we face and it's time we shut
15:03
them down thank you
15:07
[Applause]
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