IPCC Synthesis Report: What’s Actually in It?My series of blogs following the El Nino forecasts got a nice call out in Andy Revkin’s Dot Earth Opinion Piece. I’ll probably do one more update in a couple of weeks.At the beginning of November, I wrote a piece at the release of the
IPCC Synthesis Report. From the
IPCC (Intergovernmental Panel on Climate Change) website,
the “Synthesis Report (SYR) synthesizes and integrates material
contained within IPCC Assessment Reports and Special Reports. The SYR
should be based exclusively on material contained in the three Working
Group Reports and Special Reports produced during the 5th or previous
Assessment Cycles. It should be written in a ‘non-technical style
suitable for policymakers and address a broad range of policy-relevant,
but policy-neutral questions’ …” The intent of the IPCC reports is to
assess the state of the science and provide translation of science-based
knowledge to policymakers. The Synthesis Report has taken on a special
emphasis because we are building up to the
2015 Conference of Parties in Paris.
In my earlier blog I expressed frustration with the language that the
United Nations Framework Convention on Climate Change
(UNFCCC) often placed on these documents. I also was writing in
response to the press coverage that was coming out at the time of
release.
For the past two weeks we have used the report in my
current class on climate-change uncertainty in the context of decision
making. (Eight students of varied backgrounds.) What struck me most
about the report is how different the report is from what had been
reported in the press. From the press reports, it sounded as if the
document was still carrying forth the idea that dangerous irreversible
climate change was all in the future and a variety of tipping points
could be avoided with aggressive reduction of fossil fuels.
Whenever
I have my class read one of the IPCC reports I ask them first the
message of the report, who they see as the audience of the report, and
if the communication was effective. Usually they provide mixed reviews,
with statements that the language of the reports and the figures remains
encumbered with the jargon and complexity that is inherent to the
field. There is often the criticism that especially with the figures,
there is an attempt to communicate too many ideas. The response to the
text of the
Synthesis Report’s Summary for Policy Makers
was uniformly positive and enthusiastic. The authors of the report had
communicated effectively and powerfully in a way that reached not only
to policy makers but to a broader public.
The primary message:
climate change is here;
more is on the way;
we cannot avoid this;
we must adapt; and
to
keep things manageable we must also reduce our greenhouse emissions to
virtually zero – or remove carbon dioxide from the atmosphere.
If you look at the
full Synthesis Report, 116 pages, and search for “irreversible,” then you find major conclusions:
*
Warming caused by CO2 emissions is effectively irreversible over
multi-century timescales unless measures are taken to remove CO2 from
the atmosphere.
* Climate change will amplify existing risks and
create new risks for natural and human systems. Risks are unevenly
distributed and are generally greater for disadvantaged people and
communities in countries at all levels of development. Increasing
magnitudes of warming increase the likelihood of severe, pervasive, and
irreversible impacts for people, species and ecosystems. Continued high
emissions would lead to mostly negative impacts for biodiversity,
ecosystem services, and economic development and amplify risks for
livelihoods and for food and human security.
* Many aspects of
climate change and its impacts will continue for centuries, even if
anthropogenic emissions of greenhouse gases are stopped. The risks of
abrupt or irreversible changes increase as the magnitude of the warming
increases.
* Within the 21st century, magnitudes and rates of climate change associated with medium to high emission scenarios (RCP4.5, 6.0, and 8.5)
pose a high risk of abrupt and irreversible regional-scale change in
the composition, structure, and function of marine, terrestrial and
freshwater ecosystems, including wetlands (medium confidence), as well
as warm water coral reefs (high confidence).
* Without additional
mitigation efforts beyond those in place today, and even with
adaptation, warming by the end of the 21st century will lead to high to
very high risk of severe, widespread, and irreversible impacts globally
(high confidence).
* Inertia in the economic and climate systems
and the possibility of irreversible impacts from climate change increase
the benefits of near-term mitigation efforts (high confidence).The
Synthesis Report makes it quite clear than irreversible warming and
consequences of that warming have already occurred. In fact, the first
bullet in the list above states that all of the warming associated with
carbon dioxide increase is irreversible. Changes in ecosystems and
extinctions related to warming, irreversible. Current and growing
impacts of sea-level rise, irreversible.
It is also interesting
to search the full report for dangerous; it only appears twice in the
document. In neither case does the word dangerous occur in the context
that dangerous climate change can be avoided. (I feel like I am doing a
Common Core exercise.)
One
part of the report that I especially like is the template (Box 2.4 in
the document) which serves as a “starting point for evaluating dangerous
anthropogenic interference with the climate system.” This relies on
identification of “five reasons for concern:”
1) Unique and threatened systems
2) Extreme weather events
3) Distribution of impacts
4) Global aggregate impacts
5) Large-scale singular events
I include the text associated with “Large-scale singular events;”
“Large-scale
singular events: With increasing warming, some physical and ecological
systems are at risk of abrupt and/or irreversible changes (see Section
2.4). Risks associated with such tipping points are moderate between 0
and 1°C additional warming, since there are signs that both warm-water
coral reefs and Arctic ecosystems are already experiencing irreversible
regime shifts (medium confidence). Risks increase at a steepening rate
under an additional warming of 1 to 2 °C and become high above 3°C, due
to the potential for large and irreversible sea-level rise from ice
sheet loss. For sustained warming above some threshold greater than
~0.5°C additional warming (low confidence) but less than ~3.5°C (medium
confidence), near-complete loss of the Greenland ice sheet would occur
over a millennium or more, eventually contributing up to 7 m to global
mean sea-level rise.” (“Tipping points” only appears four times in the
document, once to say there is little evidence of an Arctic sea ice
tipping point.)
As we discussed the report in class, the message
that emerged from the report is that if we do not reduce our carbon
dioxide emissions by several 10s of percent, in the next 1 – 3 decades,
then the warming and its impacts will become large enough that
adaptation is not incremental; that is, adaptation will not, simply, be
modifying what we know how to do. In some cases adaptation will not be
possible – we will have to do something new, something different (
something fantastic).
It is also true that as the warming gets larger, we move outside of the
range or parameters on which our models were trained. Therefore, model
guidance becomes more unreliable.
I confess that the Synthesis Report extends further from the
language of the Framework Convention
than I expected. What is in this report is quite different than what
was in the headlines. The responses from my students suggest that the
written communication from the report is exceptional. The language is
more dispassionate than grim or alarming. The report has had its flash
in the press, now it is time for serious people to use it.
Uncertainty Definitions (from Box.Introduction.2)“The
IPCC Guidance Note on Uncertainty (2010)
defines a common approach to evaluating and communicating the degree of
certainty in findings of the assessment process. Each finding is
grounded in an evaluation of underlying evidence and agreement. In many
cases, a synthesis of evidence and agreement supports an assignment of
confidence, especially for findings with stronger agreement and multiple
independent lines of evidence. The degree of certainty in each key
finding of the assessment is based on the type, amount, quality, and
consistency of evidence (e.g., data, mechanistic understanding, theory,
models, expert judgment) and the degree of agreement. The summary terms
for evidence are: limited, medium, or robust. For agreement, they are
low, medium, or high. Levels of confidence include five qualifiers: very
low, low, medium, high, and very high, and are typeset in italics,
e.g., medium confidence. The likelihood, or probability, of some
well-defined outcome having occurred or occurring in the future can be
described quantitatively through the following terms: virtually certain,
99–100% probability; extremely likely, 95–100%; very likely, 90–100%;
likely, 66–100%; more likely than not, >50–100%; about as likely as
not, 33–66%; unlikely, 0–33%; very unlikely, 0–10%; extremely unlikely,
0–5%; and exceptionally unlikely, 0–1%. Assessed likelihood is typeset
in italics, e.g., very likely. Unless otherwise indicated, findings
assigned a likelihood term are associated with high or very high
confidence. Where appropriate, findings are also formulated as
statements of fact without using uncertainty qualifiers.”
KC Hunter / Alamy
Amy Cicconi / Alamy
Edward Parker / Alamy
