5 Conclusions
80. 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.
81. 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.
82. 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.
83. 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.
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