Further considerations: climate science and policy beyond 2013 - Climate Change: Biological and Human Aspects - page 545

Appendix4. Further considerations:climate
science and policy beyond 2013
With this topic's first edition (2007) Cambridge University Press kindly afforded
a couple of pages as Appendix 4 to allow a brief summary of the IPCC's 2007
assessment (AR4) at the topic's final page-proof stage: that assessment literally came
out a couple of months before this topic's first edition was published. This time the
IPCC's 2013 assessment (AR5) will come out several months after this edition sees
light of day and so I now use this appendix in a different way.
In the course of lectures and encounters following this topic's first edition I have
invariably been asked a number of questions as to my personal thoughts, as opposed
to recounting the climate science and policy developments. Other than comment-
ing on likely prospective research and policy analysis avenues, in the main I have
shied away from answering, especially as most people have expected me to be pre-
dictive: what will happen to such and such in coming decades? And of course
nobody can predict the future. Having said that, I do have some personal thoughts
on climate science and policy. Given that there has been interest in my own take
beyond that of appraising the literature, I now make a couple of points in this short
appendix, quite separate from the main body of the text: I do not wish to contaminate
my earlier (hopefully) sober review of the science and policy with wilder personal
musings.
First, on the policy front, I feel sincerely that there is a pressing need for the
way nations account for fossil carbon emissions to be more rigorous. It is not just
that international aviation and shipping emissions are excluded, but the problem
of economic carbon leakage between nations. The way the figures are currently
calculated purely relate to a nation's in situ greenhouse gas emissions. To take the
UK as an example, carbon dioxide equivalent (CO 2 -eq) greenhouse gas emissions
have - according to the way they are currently calculated - been in decline since
1991-2 to the present (2011 being the last full year of data at the time of writing).
Yet the UK imports manufactured goods and also imports very roughly half its food.
Fossil energy and fertiliser (part fossil-based) are used to provide these. Of course,
some of this currently unaccounted fossil carbon will be offset by UK exports, but
only a proportion: the UK is by far a net importer of unaccounted carbon. When
looking at UK emissions, and those of other individual nations, what is needed are
additional metrics to take this carbon leakage into account. Nations need to know
how much greenhouse gas emission their citizens are causing through their 'total
net emissions'; that is, imports less exports. Of course, care needs to be taken to
avoid double accounting but the bottom line is that a further metric still is needed:
the net total fossil carbon used to generate a pound (or dollar), which is effectively
total net emissions divided by GDP. This is a measure of the economy's fossil carbon
efficiency.
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