Science summary
BAMOS
Jun 2019
Unprecedented high temperatures
over the coming century
Scott Power and François Delage
Bureau of Meteorology, Email: [email protected]
Note from the Editor: This science summary provides a synthesis of the research published in Nature Climate Change. For
more information, read the journal article 'Setting and smashing extreme temperature records over the coming century'.
Changes in the intensity or frequency of extreme climate events
can profoundly increase the disruption caused by climate
change. Unprecedented extreme events can be particularly
challenging to people and ecosystems. The more extreme these
events are, the greater the potential to push ecosystems and
communities beyond their ability to cope. under a high emissions scenario. Records will tend to be set
more frequently in the poorest countries: approximately 68%
of years will see extreme temperature records set in the world’s
least developed countries and in Small Island Developing
States, whereas this figure is only 54% in wealthier nations.
These figures all drop to approximately 14% under RCP2.6.
This research examines future high monthly mean temperature
records that will be so extreme they will not have been
experienced previously. The paper provides projections of the
rate of extreme high temperature record setting and record
‘smashing’—when a record exceeds the record it replaces by a
large amount—over the coming century. These findings highlight the benefits of reducing global
greenhouse emissions by the end of the 21st century in terms
of reducing the pace of extreme temperature record-setting
and record-smashing. However, the study also finds that even
if emissions are markedly and sustainably reduced, the benefits
take twenty years or more to kick in. This means that people who
manage systems affected by extreme high temperatures will
need to start considering and managing risks associated with
the frequent occurrence of unprecedented high temperatures
for at least the next twenty years—longer if global emissions
are not markedly reduced.
By the late 21st century, many more extreme monthly maximum
temperature records are projected to be set under a high
emission scenario (RCP8.5) than under a low emissions scenario
(RCP2.6) (Figure 1), and far more of the records will be ‘smashed’
Figure 1. a) Record setting and b)
historical record breaking during
the 21st century. Percentage area in
years shown breaking the highest
value attained a. prior to the year
(n) indicated (i.e., during 1900 to
n-1) and b. during the historical
period used here (i.e., 1900–2005)
only. RCP8.5 (pink), RCP2.6 (blue),
and both the pre-industrial control
simulation (grey) and its theoretical
estimate (black dashed lines). Note:
the percentage area in each year
is also an estimate of the global
average likelihood that at least one
monthly record was set in the same
year. Solid lines give multi-model
means using 22 CMIP5 climate
models. Shading indicates the full
model range.
Source: Power, S.B., and F.P.D.
Delage, 2019: Setting and smashing
extreme temperature records over
the coming century. Nature Climate
Change, https://www.nature.com/
articles/s41558-019-0498-5.
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