Climate Change Predictions _EMG _Steve Law

Setting the Scene
• What do we know about climate change?
• What can we predict?
• What must we adapt to?
IPCC 2013 Headlines
What can we see?
• Global warming is unequivocal, as is the evidence of human
• Surface temperatures are increasing, ice-sheets are melting, sealevel is rising
• Each of the last three decades has been successively warmer than
any preceding decade since 1850. In the Northern Hemisphere,
1983–2012 was likely the warmest 30-year period of the last 1400
• The atmospheric concentrations of carbon dioxide (CO2), methane,
and nitrous oxide have increased to levels unprecedented in at least
the last 800,000 years. CO2 concentrations have increased by 40%
since pre-industrial times, primarily from fossil fuel emissions and
secondarily from net land use change emissions.
IPCC 2013 Headlines
What does this mean?
• Global surface temperature change for the end of the
21st century is likely to exceed 1.5°C relative to 1850 to
1900 (most conservative models).
• Changes in temperature and rainfall patterns will not be
uniform. Generally, wet regions will become wetter and
dry regions will become dryer
• Global mean sea level will continue to rise
• Global warming will exacerbate the increase of CO2 in
the atmosphere (positive feedback)
• Most climate change impacts will persist for many
centuries even if emissions of CO2 are stopped today.
What do we know?
Fossil fuel use is
Atmospheric CO2 levels
are increasing
Temperatures are
Increased global
temperature = localised
changes in climate
patterns (seasons, rainfall,
evaporation, wind, etc)
Impact on agriculture =
major social & economic
What can we predict?
Proceed with caution!!
Projected changes in average seasonal temperature (˚C)
by 2036-2065 relative to the 1961-2000 period
Projected changes in mean seasonal rainfall (mm)
for the period 2036-2065, relative to 1961-2000
Projected change in annual frequency of
extreme rainfall events (more than 20mm per day)
for the period 2035-2065 relative to the baseline period 1961-2000.
Projected change in annual frequency of very hot days
(over 35° C)
for the period 2035-2065 relative to the baseline period 1961-2000.
How can climate
models help us
understand possible
changes in local
Implications for
adaptation and
policy actions
requires local
Reporting frequency to WMO from World Weather watch stations 1998-2002
What exactly do we need to adapt to?
• Models can’t give more than broad
probabilities – rainfall, temperature,
extreme events…..
• …but we can be certain of uncertainty
• International processes will not solve your
• Building resilience: Social dimension is as
important as technical