Download Very likely

Climate Change Information Seminar
Intergovernmental Panel on Climate Change
Fourth Assessment Report (AR4)
– the relevance to FAO’s activities
Claudia Hiepe
Hideki Kanamaru
NRCB
Nov 27th Tuesday 14:00-15:30 German Room
Dec 3rd Monday 10:00-11:30 Iran Room
Three Volumes of IPCC Fourth
Assessment Report (AR4)
WG1 152 authors,
600 reviewers,
996pp., technical
summary 74pp.
WG2 173 lead
WG3 168 lead
authors, 183
authors + 85
contributing authors, contributing authors,
910 reviewers,
485 reviewers,
976pp., technical
896pp., technical
summary 56pp.
summary 70 pp.
IPCC 2007 WG 1
– The Physical Science Basis
• Observed Changes in Climate
• Attribution of Change
• Projected Change
Observed changes since 1850
Figure SPM .3
Precipitation trend
Detection of Climate Change
• Observed change is significantly
different (statistically) than natural
internal variability of climate.
•
•
•
•
Virtually certain > 99% probability
Extremely likely > 95% probability
Very likely > 90% probability
Likely > 66% probability
•
•
•
Very high confidence : at least 9 out of 10 chance of being correct
High confidence : about 8 out of 10
Medium confidence : about 5 out of 10
Observed trends in climate with respect
to natural internal climate variability
• Drought affected area increased since 1970s. (likely)
• Cold days and nights have become less frequent, hot
days and hot nights have become more frequent over
the past 50 years. (very likely)
• Heat waves have become more frequent. (likely)
• Heavy precipitation events have become more
frequent. (likely)
• Average NH temperatures during 2nd half of the 20th
century were higher than during any other 50-year
period in the last 500 years (very likely) and the
highest in at least the past 1300 years (likely).
Observed Changes in Natural and Human
Environments due to recent warming
• Earlier timing of spring events. (very high confidence)
• Poleward and upward shifts in plant and animal
ranges. (very high confidence)
• Shifts in ranges and changes in algal, plankton and
fish abundance in some marine and freshwater
systems. (high confidence)
• Agricultural and forestry management at NH higher
latitudes – earlier spring planting of crops and
alterations in disturbance regimes of forests due to
fires and pests. (medium confidence)
Attribution of Change
• Demonstrate that observed changes are
– Unlikely to be entirely within internal climate
variability.
– Consistent with estimated responses to external
anthropogenic forcings, i.e., most importantly GHG
emissions.
– Not consistent with other explanations.
• Most of the observed increase in globally-averaged
temperatures since the mid-20th century is due to the observed
increase in anthropogenic GHG concentrations. (very likely); on
continental scale (likely); regional and smaller scales (attribution
is difficult)
Changes in surface temperature since 1900 –
obs vs model
Figure SPM .4
GHG concentrations variations over the last
10,000 years
CO2
• Global GHG emissions
have grown since preindustrial times, with an
increase of 70% between
1970 and 2004. (high
agreement, much
evidence)
CH4
N2O
Human Activities and GHGs
• Global increases in CO2 concentrations are due
primarily to fossil fuel use, with land-use change
providing another significant but smaller contribution.
• CH4 concentration increase is predominantly due to
agriculture and fossil fuel use.
• The increase in N2O concentration is primarily due to
agriculture (fertilizers).
Global average radiative forcing
cooling
The net effect of
human activities
since 1750 is
warming. (very
high confidence)
warming
Projected Changes
• Global GHG emission will continue to grow over the next few
decades with current policies and practices. (high agreement
and much evidence)
• Further warming during the 21st century would be larger than
those observed during the 20th century. (very likely)
For the next two decades:
• 0.2 °C per decade for a range of emissions scenarios.
• 0.1 °C per decade even if GHG concentrations had been kept
constant at year 2000 levels.
2090-2099 projection relative to 1980-1999
• 1.1-6.4 °C increase
Surface warming projections
Projected surface temperature changes
• Warming greatest over land and high latitudes NH.
• Warming least over Southern Ocean and parts of the
Figure SPM .6
North Atlantic Ocean.
Precipitation changes for the period 2090-2099,
relative to 1980-1999
• Precipitation increases in high latitudes. (very likely)
• Precipitation decreases in most subtropical land
regions. (likely)
Figure SPM .7
Projections of extreme events
• Warmer and fewer cold days and nights, warmer and more
frequent hot days and nights (Virtually certain)
• Increase in frequency of hot extremes, heat waves, and heavy
precipitation. (very likely)
• Increase in tropical cyclone intensity, drought affected area.
(likely)