This weekend I finally got the opportunity to read Dr.
Matt Ridley’s recent essay “The
Climate War’s Damage to Science” in the Quadrant Online. As a fellow Lukewarmer
I try to keep abreast of Dr. Ridley’s essays and articles and am seldom
disappointed by his prose. This article, like most of his work, made for a very
interesting read and I would recommend it to anyone interested in the topic of
climate change politics. While reading the essay one particular paragraph
jumped out at me. The paragraph described one of the Representative
Concentration Pathways (RCPs) used in the IPCC Fifth Assessment Report. In the essay Dr. Ridley wrote:
What
is more, in the small print describing the assumptions of the “representative
concentration pathways”, it admits that the top of the range will only be
reached if sensitivity to carbon dioxide is high (which is doubtful); if world
population growth re-accelerates (which is unlikely); if carbon dioxide
absorption by the oceans slows down (which is improbable); and if the world
economy goes in a very odd direction, giving up gas but increasing coal use
tenfold (which is implausible).
This paragraph reminded me that I had previously
committed to writing about the IPCC RCPs and in particular about RCP8.5 which
is often referred to, incorrectly, as the “Business as Usual Scenario”. The
reason for my interest in this rather anodyne topic is that it actually
represents a quite excellent example of how science is misrepresented to the
public in the climate change debate.
As I describe in my post “Does
the climate change debate need a reset? - on name calling in the climate change
debate” one of the critical battles in any debate is control over the labelling
of the actors. If you can apply the best possible label to yourself and the least
agreeable label to your opponent you immediately gain the upper hand. In the
climate change debate, the “Business as Usual” label has been used more times
that I can count with activists from the folks at Skeptical Science
to the Suzuki
Foundation, and from the
Pembina Institute to 350.org
all finding some way to slip that
phrase into their calls demanding immediate action (and of course donations to
their cause). As this post will demonstrate, however, the “Business as Usual” descriptor
used by the activists in the climate debate is nothing of the sort. Rather it is
an artifact from earlier versions of the IPCC reports and was conspicuous by
its absence in the most recent (Fifth Assessment) report.
Let’s start with some background. As anyone who has
read my writing knows one of the ways to make science more reader-friendly is
to use analogies and personal anecdotes. Of course the risk with analogies is
that a bad analogy can distract from your narrative. Similarly, anecdotes can
personalize your writing and make it more approachable but anecdotes are only
valuable if they are subsequently supported by actual data since the old saw
goes “the
plural of anecdote is not data”. In this vein, the earliest IPCC reports
used “Scenarios” to inform their modelling exercises. As they put it:
Scenarios
are images of the future, or alternative futures. They are neither predictions
nor forecasts. Rather, each scenario is one alternative image of how the future
might unfold. A set of scenarios assists in the understanding of possible
future developments of complex systems. Some systems, those that are well
understood and for which complete information is available, can be modeled with
some certainty, as is frequently the case in the physical sciences, and their
future states predicted. However, many physical and social systems are poorly
understood, and information on the relevant variables is so incomplete that
they can be appreciated only through intuition and are best communicated by
images and stories. Prediction is not possible in such cases (ref).
I have neither the time nor the expertise to discuss
the scenarios is a manner worthy of them and so will leave that to Dr. John
Nielsen-Gammon from Texas A&M University who has prepared a brief breakdown
on the history of the different scenarios used by the IPCC (ref).
He also describes the process by which the most recent IPCC Report eliminated
these scenarios. The reason for this is simple, by 2014, the older scenarios
had outlived their usefulness. The public was no longer in need of
spoon-feeding and instead the RCPs were rolled out. Four RCPs were generated
for the Fifth Assessment report representing four different forcing pathways. A
simplified definition of a “forcing” is the difference between the energy from
the sun absorbed by the earth and that radiated out into space (ref).
The four RCPs were labeled by the approximate radiative forcing (in watts per
meters squared) expected to be reached by following the respective pathways during
or near the end of the 21st century. The four pathways are RCP2.6, RCP4.5,
RCP6.0, RCP8.5 (ref).
The roles of the RCPs, therefore, were not to inform the public as much as to
inform the modellers in the IPCC process. Specifically, they were intended to
drive the climate model simulations that formed the basis of many of the future
projections in the most recent IPCC report (ref).
To put it another way, RCP8.5 was a pathway designed to model a set of
conditions that could lead to a world where climate forcing by the year 2100
reached 8.5 watts per meter squared. It was essentially designed to provide a
worst-case scenario [used in its traditional literary sense] if everything in
the world went sideways or backwards (as I will detail later).
The problem with the IPCC retiring its old scenarios is
that a lot of activists were very happy with the old paradigm and had no desire
to change their tunes. They wanted something that they could sink their teeth
into and use to scare the public and politicians. Since the IPCC had taken away
their well-established tools they appear to have decided to re-label one of the
new tools to suit their purposes. So they affixed the retired “Business as
Usual” scenario label (some use the term “status quo”) to RCP8.5 and continued
on their merry way scaring up new funding. The only problem is that, by
definition, RCP8.5 was not a “Business as Usual” scenario, rather it was
developed to
represent a high-end emissions scenario. “Compared to the scenario literature
RCP8.5 depicts thus a relatively conservative business as usual case with low
income, high population and high energy demand due to only modest improvements
in energy intensity.” (Riahi et al. 2011 ref) RCP8.5 comes in around the 90th percentile of published
business-as-usual (or equivalently, baseline) scenarios, so it is higher than
most business-as-usual scenarios. (van Vuuren et al. 2011a ref)) - (Text ref)
What the
activists call: “Business as Usual” actually represents the 90th
percentile of the scenarios prepared for the IPCC that involved little change
in environmental and economic policies (sometimes referred colloquially as the “no
significant action” scenarios). These scenarios represented the worst of the
worst where governments and industry did not do anything to improve their lot. As
such the no significant action scenarios could only be described as “business
as normal” if you happened to be living in 1990 or 1996 when the IPCC prepared
its original couple reports. That would be before we had spent 20 or so years
learning about climate change; before the Kyoto Protocol and the world-wide
drive to renewable energy; before the discovery of tight shale gas and the move
away from coal as the primary source of future energy plants in much of North
America, Europe and Asia. To put it simply, being at the 90th
percentile of that group put you in pretty impressive company and does not
relate to anything that anyone in the real world would actually expects to
happen. Rather, in a relative sense as the 90th percentile of all those
earlier estimates, it would be the scenario that comes just below the scenario where
Godzilla emerges from the sea to burn Tokyo and the scenario where the
atmosphere spontaneously combusts from the endless bursts of Hiroshima-bomb-powered
forcings.
I have
made a pretty bold statement that RCP8.5 is not really relevant in a real-world
sense and I suppose it is time to back that up with data. In order to
understand how RCP8.5 has already been trumped by history you need to look at
the history and contents of RCP8.5. Readers interested in the details should
read the paper by Riahi (et. al. 2011
ref). Dr. Riahi is one of the authors of the
original IPCC Scenarios upon which RCP8.5 was based in 2007 (ref). At that time, consistent with the education
theme each IPCC Scenario had a “Storyline”. The storyline described the
assumptions of the scenario in easy to understand language. The “Storyline” for
RCP8.5 originates from Scenario A2 in the Third IPCC Report but was further
refined in Riahi (et. al. 2007 ref) as A2r. As recounted in the Third IPCC
Report (and detailed in these references (ref ref and ref) the A2 storyline was characterized by:
· lower trade
flows, relatively slow capital stock turnover, and slower technological change;
· less
international cooperation than the A1 or B1 worlds. People, ideas, and capital
are less mobile so that technology diffuses more slowly than in the other
scenario families;
· international
disparities in productivity, and hence income per capita, are largely
maintained or increased in absolute terms;
· development
of renewable energy technologies are delayed and are not shared widely between
trade blocs;
· delayed land
use improvements for agriculture resulting in increased pollution and increased
negative land use emissions until very late in the scenario (close to 2100);
· a rebound in
human population demographics resulting in human population of 15 billion in
2100; and
· a 10 fold
increase in the use of coal as a power source and a move away from natural gas
as an energy source.
Looking at what the activists have labelled the “Business
as Usual” scenario we see a slew of assumptions that are anything but business
as usual. It is generally accepted in the demographic circles that the human
population will max out at between 10 and 12 billion (ref)
so the population estimate is off by around 25%. Rather than trade blocs hoarding
technologies we are living in an increasingly international world where technological
improvements move at the speed of the internet and new and improved renewable
energy technologies are both being developed and shared worldwide. Coal use is
decreasing as a percentage of our energy supply and the shale revolution and
access to cheap and plentiful natural gas has resulted in an international market
for liquefied natural gas and increases in energy intensities not decreases. To
put it bluntly, virtually every one of the assumptions of the RCP8.5 have been
demonstrated to be categorically wrong. No surprises here, when the IPCC picked
a worst case scenario they went full bore on that approach.
I see I am
running long so let’s summarize this post. When you see an abstract where the
authors say something like:
We show that
although the global mean number of days above freezing will increase by up to
7% by 2100 under “business as usual” (representative concentration pathway
[RCP] 8.5), suitable growing days will actually decrease globally by up to 11%.... tropical areas could lose up to 200
suitable plant growing days per year....Human
populations will also be affected, with up to ~2,100 million of the poorest
people in the world (~30% of the world’s population) highly vulnerable to
changes in the supply of plant-related goods and services (ref).
It is time
to gently close the journal and back away slowly so as to not attract the
author’s attention. By basing their study on RCP8.5 and specifically referring
to it as the “business as usual” scenario the authors have told you all you
need to know about the reliability of their paper. Similarly when an activist
talks about “business as usual” in their sales pitch, it is time to put your
wallet back in your pocket. If you are so inclined then it is it is time for you to find a group that is
more serious about improving our planet and more in keeping with what the IPCC actually has to say. RCP8.5 is not a business as usual scenario
but rather a future scenario that has been soundly invalidated by the conditions in the present.