Current warming and likely future impacts - Climate Change: Biological and Human Aspects - page 315

and East Anglia would only get wetter by 40 mm. This was based on the UKCIP
model UKCIP98. Compare this to the UKCIP02 model forecasts used in 2002, which
predicted the opposite for winter 2050, that the south east of the UK would have
more rain and the north west of Scotland would remain within the natural variability
of 1961-90. It is because of such vagaries that successive MONARCH reports, and
other UK policy reports, did not build on the results of previous models but built on
policy methodologies and understanding, while starting afresh each time using the
latest computer climate models.
In 2002 the UKCIP updated its first (1998) climate change scenarios for the UK
(Hulme et al., 2002). That in Britain (more so than in the USA) climate change issues
were of considerable political concern, both by the Government and the opposition
parties, is indicated by the Secretary of State Margaret Beckett personally endorsing
the report with an introduction. UKCIP02 took four carbon-emission scenarios (low,
medium-low, medium-high and high), which were based on the IPCC Special Report
on Emission Scenarios (or SRESs) (IPCC, 2000). These in turn were related to change
from a 1961-90 baseline to 2011-40 (labelled the 2020s), 2041-70 (the 2050s) and
2071-2100 (the 2080s).
It concluded that by the 2080s:
temperatures across the UK may rise by between 2 (low-emission scenario) and
3.5 ◦ C (high-emission scenario), with the greatest warming being in the south and
east and greater warming in the summer than winter (parts of the south east may
be up to 5 ◦ C warmer in the summer);
high summer temperatures will become increasingly frequent, and cold winters
rare;
winters will become wetter and summers drier. Overall the UK will become drier
as the winters are expected to become only 30% wetter while the summers may
have only 50% of the precipitation;
days of heavy rain are likely to increase in frequency;
the sea level will rise between 26 and 86 cm in the south east of England but, due to
geological (isostatic) rise, the sea level may fall by 2 cm (low-emissions scenario)
or rise by 58 cm (high-emissions scenario) in western Scotland;
the Gulf Stream is unlikely to weaken its warming of the UK, but there is uncertainty
due to lack of detailed knowledge of interactions between ocean circulation and
climate.
(Note: the above UKCIP 2002 scenario forecasts were changed slightly in 2009, as
we shall shortly see.)
In 2007 UKCIP produced the first of the UKCIP08 reports, The Climate of the
United Kingdom and Recent Trends report (Jenkins et al., 2007). It looked at historic
trends and showed that in the 19th century through to the early years of the 21st
century there had been clear warming and changes in precipitation. It noted that
Central England Temperature (CET) had risen by about a degree Celsius since the
1970s, with 2006 being the warmest year on record to date. Sea-surface temperatures
around the UK coast had risen over the past three decades to 2007 by about 0.7 ◦ C. It
noted that regions of the UK had experienced an increase over the past 45 years in the
contribution to winter rainfall from heavy precipitation events; in summer all regions
except north-east England and northern Scotland showed decreases. It concluded that