Conclusions and recommendations
Process
1. The
IPCC has continued to strengthen and improve its Assessment Report
procedure. The IPCC has put a series of measures in place to help
to minimise the risk of errors creeping in, and quickly rectify
them if they emerge. The IPCC has responded extremely well to
the constructive criticism of the InterAcademy Council (IAC).
With regard to the IAC's recommendations, we would like to see
the appointment of non-climate scientists to the Executive Committee.
(Paragraph 10)
2. For future Assessment
Reports the Government should recommend to the IPCC that they
recruit a small team of experts who are not climate scientists
to observe the review process from start to finish. The team would
not constitute an extra stage of review, but rather oversee the
process and arbitrate when controversies arise. The testimony
of this independent team would improve the credibility of the
report when it is released, and potentially protect it from any
unnecessary and unfounded criticism. The team could also feed
back to the IPCC in order to facilitate continuous improvement.
(Paragraph 12)
Inclusivity and objectivity
3. The
Assessment Report procedure depends to a large extent on the integrity
of the authors and editors involved, but we have found no evidence
to suggest that this should give cause for concern. The authors
drew upon a wide pool of peer-reviewed literature, highlighting
areas of disagreement as readily as areas of agreement. We are
satisfied that there was no systemic bias of any kind, be it financial,
political or otherwise that would jeopardise the accuracy of the
reported scientific conclusions. The procedures in place to safeguard
against the influence of such biases appear to be sufficiently
robust. (Paragraph 20)
4. Although the terms
"consensus" and "settled science" with regards
to climate change were generally not thought to be helpful, as
uncertainty and debate are required to drive research forward,
we conclude that there is clearly strong agreement that the IPCC
has captured the prevailing scientific opinion, notwithstanding
some disagreement from a number of reputable scientists. (Paragraph
22)
Timeliness
5. There
are mixed views regarding the frequency and size of IPCC Assessment
Reports. Transition to smaller, more frequent reports would arguably
relieve the burden on contributing authors and ensure policymakers
were kept up to date, but the finished document would lack the
comprehensive and authoritative nature of the current Assessment
Reports. Any revision of the tried and tested IPCC formula should
only be introduced after careful consultation with both the governments
who use the IPCC reviews and the scientists who write them. The
aftermath of AR5 is an optimum time for this period of reflection
to take place. (Paragraph 26)
Summary for Policymakers
6. Including
policymakers in the final stage of the report writing process
does not seem to have had any substantial negative effects on
the Summary for Policymakers (SPM) and very likely serves to improve
the relevance and accessibility of the finished document. (Paragraph
31)
7. It is inevitable
that the distillation of such a complex and lengthy report will
lead to the omission of some technical detail, but the traceability
of the SPM to the full report adequately compensates for that.
Any further technical detail that may be required for policymaking,
such as in the setting of carbon budgets, is readily obtainable.
The SPM succeeds in its purpose of keeping policymakers informed
on issues surrounding climate science. (Paragraph 32)
8. We recommend that
the Government call on the IPCC to introduce a greater level of
transparency in the plenary meetings to agree future Summaries
for Policymakers (SPM). This may be through the admission of the
independent team of observers to oversee the discussions (see
paragraph 12). The feedback from the team would then serve to
provide reassurance that the summary-writing process has been
carried out objectively. (Paragraph 33)
Causes of climate change
9. The
WGI contribution to AR5 presents the most compelling evidence
to date that many of the changes to the climate recorded in the
latter half of the 20th Century were driven by post-industrial
human activity. We have not found convincing evidence that challenges
the IPCC's conclusion in this matter. There is increased confidence
in the IPCC projections that, with rising greenhouse gas concentrations,
we will continue to see warming (and the changes to the climate
associated with warming) in this century and beyond. (Paragraph
42)
Sensitivity of the climate to carbon dioxide
10. The
WGI contribution to AR5 has considered the full range of both
Equilibrium Climate Sensitivity and Transient Climate Response
and given the best assessment possible within the constraints
of the evidence available at the time. It does not appear that
a consistent pattern for higher or lower sensitivities than that
stated in the WGI contribution to AR5 has emerged since its publication.
(Paragraph 48)
The hiatus
11. Periods
of hiatus are consistent with earlier IPCC assessments that non-linear
warming of the climate is to be expected and that forced climate
changes always take place against a background of natural variability.
The current period of hiatus does not undermine the core conclusions
of the WGI contribution to AR5 when put in the context of the
overall, long-term global energy budget. Despite the hiatus, the
first decade of the 2000s was the warmest in the instrumental
record and overall warming is expected to continue in the coming
decades. (Paragraph 53)
Climate models
12. The
models used in the IPCC's Assessment Reports have a successful
history of simulating past climate and their future projection
of substantial warming over the next century in all but the most
aggressive mitigation scenarios is well founded and overwhelmingly
clear. (Paragraph 64)
13. In the light of
the WGI contribution to AR5, the Government should commission
a strategic review of UK modelling facilities to discern how current
computing capacity could be used more effectively to reduce remaining
uncertainties. The review should highlight areas of potential
national and international collaboration between modelling centres
and any funding shortfalls that need to be met. (Paragraph 65)
Economic implications
14. The
Government should ensure that the report it has commissioned to
look at the benefits and opportunities in tackling climate change,
The New Climate Economy, considers evidence about the costs of
climate change to business. We believe that this report should
be peer reviewed to avoid attracting the same criticism that was
made of the Stern Review. (Paragraph 70)
Domestic climate policy
15. We
believe that the Committee on Climate Change (CCC) was right to
consider a range of values for climate sensitivity (and their
relative uncertainties) when reviewing the Fourth Carbon Budget.
We agree with its conclusion that the IPCC's latest assessment
of the sensitivity of the climate towards greenhouse gas emissions
gives no grounds for a change in policy action. (Paragraph 73)
16. The WGI contribution
to AR5 re-affirms the scientific underpinning of the Climate Change
Act 2008 and hence the UK's ambitious greenhouse gas emission
reductions targets. We believe that there is merit in considering
embedded carbon emissions alongside territorial emissions in the
policy making process. (Paragraph 75)
International climate policy
17. The
WGI contribution to AR5 strengthens the scientific case for rapid,
drastic action to reduce global greenhouse gas emissions in order
to avoid a 2° Celsius rise in global mean surface temperature
(GMST). It is generally agreed that such dramatic emissions reductions
strategies could best be implemented within the framework of a
unified global agreement. Attempts to reach an agreement in the
past have lacked early high level leadership: a public commitment
from the UK Government is required early in the preparations of
COP 2015 in order to guarantee the highest chance of success.
(Paragraph 78)
18. The Government
should provide an explicit commitment on the involvement of senior
figures in the early stages of the Paris COP 2015. Senior Government
members should be actively involved in the strategy for obtaining
a global climate deal. The early commitment of the Prime Minister,
Chancellor of the Exchequer and DECC ministers to the preliminary
stages of the global climate negotiations will encourage other
world leaders to similarly get involved. (Paragraph 79)
Overall conclusions
19. The
conclusions of this inquiry are very clear: the WGI contribution
to AR5 is the best available summary of the prevailing scientific
opinion on climate change currently available to policy-makers.
Its conclusions are derived with a high confidence from areas
of well understood science. Uncertainty remains in a small number
of important areas but these are diminishing. It is important
to consider all lines of evidence together when assessing climate
change rather than focusing on particular aspects of the report.
The overall thrust and conclusions of the report are widely supported
in the scientific community and summaries are presented in a way
that is persuasive to the lay reader. (Paragraph 80)
20. The size and scale
of the report reflects the huge effort by the international climate
science community, who volunteer their time and expertise. We
can now be more confident than ever that human activity is the
dominant cause of the warming witnessed in the latter half of
the 20th Century. The most significant human impact is through
the release of carbon dioxide, which is predicted to continue
to cause warming in the coming decades and centuries. (Paragraph
81)
21. The IPCC has updated
its processes. The WGI contribution to AR5 is the most exhaustive
and heavily scrutinised Assessment Report to-date. Tightened review
processes ensure that the report has been compiled to the highest
standards of scholarship; a remarkable feat given the size of
the operation. The authority of the reports comes not from the
process and procedure, but from the evidence itself, the thousands
of peer-reviewed academic papers that form a clear and unambiguous
picture of the state of the climate. Collectively, this evidence
reveals a pattern of expanding observations, increasing computational
ability and improving understanding across the climate system.
There are, as there ever will be, uncertainties in the science,
but these uncertainties do not blur the overwhelmingly clear picture
of a climate system changing as a result of human influence. The
report offers an excellent vantage point from which the scientific
community can reflect on the state of climate science, and develop
research strategies for the future. (Paragraph 82)
22. The implications
of the report for policy-makers in the UK are simple: there is
no scientific basis for downgrading the UK's ambition to reduce
greenhouse gas emissions. It is imperative that this message is
also understood by the international community. The Government
must renew its commitment to achieve a global deal on climate
change. (Paragraph 83)
| 
