Transcript Speaker 1 by Dr Yap Kok Seng - Jabatan Meteorologi Malaysia

Climate Change and Extreme Weather:
IPCC Findings
by:
Yap Kok Seng
Malaysian Meteorological Department
Ministry of Science, Technology and Innovation
National Seminar on Socio-Economic Impact of Extreme Weather and Climate Change
21-22 June 2007, Putrajaya Marriott Hotel
SCOPE
Introduction:
- trends in climate variables
- sea level
- extreme weather
Future Climate:
- climate scenarios
- climate projections
Climate Variability:
- El Nino
Concluding Remarks
Annual Temperature Trend for 1901 to 2005 (above)
and 1979 to 2005 (below)
Peninsular Malaysia
~ 0.5oC per Century
Malaysia
~ 0.1oC per Decade
Source:
IPCC, 2007
Annual Rainfall Trend for 1901-2005 (above)
and 1979-2005 (below)
Peninsular Malaysia
~ 3% per Decade
Drier
Wetter
Source:
IPCC, 2007
Changes in Temperature, Sea Level and Northern
Hemisphere Snow Cover Relative to 1961–1990 Averages
Increase in global average
temperature, 100-year
linear trend (1906 – 2005):
0.74oC [0.56 to 0.92]
Rate of global average
sea level rise,
Over 1961 – 2003:
1.8 mm per year [1.3 to 2.3]
Over 1993 – 2003:
3.1 mm per year [2.4 to 3.8]
Source:
IPCC, 2007
SEA LEVEL HAS RISEN BY 0.2-0.3 METERS IN
LAST CENTURY
Have tropical cyclones become
more extreme?
Number of intense hurricanes has increased
100
Cat. 1
80
Cat. 2+3
60
Cat. 4+5
Webster, Holland, Curry and Chang (2005)
How about smaller scale severe weather systems such as
thunderstorms and tornadoes?
Water Sprout at Kudat, 2006
Recent Trends of Extreme Weather Events and Assessment
of Human Influence on the Trend (IPCC, 2007)
Phenomenon and
direction of trend
Likelihood that trend
occurred in late 20th
century (typically
post 1960)
Likelihood of a
human contribution
to observed trend
Virtually certain:
> 99% probability of
occurrence
Extremely likely:
> 95%
Warmer and fewer cold days
and nights over most land
areas
Very likely
Likely
Warmer and more frequent
hot days and nights over
most land areas
Very likely
Likely (nights)
Warmer spells / heat waves.
Frequency increases over
most land areas
Likely
More likely than not
Likely:
> 66%
Heavy precipitation events.
Frequency (or proportion of
total rainfall from heavy falls)
increases over most areas
Likely
More likely than not
More likely than
not: > 50%
Likely in many
regions since 1970s
More likely than not
Likely in many
regions since 1970
Unlikely:
< 33%
More likely than not
Likely
More likely than not
Area affected by droughts
increases
Intense tropical cyclone
activity increases
Increased incidence of
extreme high sea level
(excludes tsunamis)
Very likely:
> 90%
Very unlikely:
< 10%
Extremely unlikely:
< 5%
Future Climate:
- climate scenarios
- climate projections
Multi-model means of surface warming relative to 1980-1999 for the
scenarios A2, A1B and B1. Numbers indicate the number of models which
have been run for a given scenario. The gray bars at right indicate the
best estimate (solid line within each bar) and the likely range assessed for
the SRES marker scenarios. (IPCC, 2007)
Projected global average temperature changes for the early and late
21st century relative to the period 1980 – 1999, as calculated by multimodel averages for a low (B1), a medium (A1B) and a high SRES
scenario for the decades 2020-2039 (left) and 2090-2099 (right). (IPCC,
2007)
Projected global average precipitation changes for the late 21st century
(2090-2099) relative to the period 1980–1999. The estimates are based on
multi-model average projections for the medium (A1B) scenario for
December to February (left) and June to August (right). White areas are
where less than 66% of the models agree in the sign of the change and
stippled areas are where more than 90% of the models agree in the sign of
the change. (IPCC, 2007)
SEA LEVEL RSIES AT END OF 21ST CENTURY
Smaller range in sea level rise compared to TAR because of improved
information on uncertainties in the projected contributions c
pared to TAR
Projections for Extreme Weather Events (IPCC, 2007)
Phenomenon and direction
of trend
Warmer and fewer cold days
and nights over most land
areas
Warmer and more frequent
hot days and nights over
most land areas
Warmer spells / heat waves.
Frequency increases over most land areas
Heavy precipitation events.
Frequency (or proportion of
total rainfall from heavy falls)
increases over most areas
Area affected by droughts
increases
Intense tropical cyclone
activity increases
Increased incidence of
extreme high sea level
(excludes tsunamis)
Likelihood of future
trends based on
projections for 21st
century using SRES
Scenarios
Virtually certain
Virtually certain
Very likely
Very Likely
Likely
Likely
Likely
Future climate over Pacific (El Nino/La Nina) :
• Weak shift towards towards average background conditions which may be
described as “El Nino” like
• Eastward shift in mean precipitation
• Weakened tropical Circulation
• Continued inter-annual variability of ENSO
• No consistent indication of discernable changes in amplitude or frequency
of ENSO
NORTH ATLANTIC THERMOHALINE CIRCULATION
– approx 25% reduction by end of 21st century
pH reduction between 0.14 to 0.35 units in the 21st century adding to the present decrease of 0.1 units
From pre-industrial times
Abnormal weather in 2005 & 2006 – Is it due to Climate Change or Climate
Variability?
Thunderstorm and Strong Winds at Subang Jaya, 9 Mac 2006
Haze in Kuala Lumpur on 3 October 2006
Lightening caused fire at Pasir Gudang Port, Johore
on 18 April 2006
Flood in Kota Tinggi, Johore on 29 December 2006.
Warmer winter
&
late
onset
Is it due to Climate Change
or
Climate Variability?
Late ending of
tropical storm
season
Warmer sea surface
temperature
Late onset of
northeast
monsoon
These conditions had caused complex
interaction within the atmosphere and
ocean circulation system
El-Nino Warmer
sea surface
temperature
Late onset of
Australia/Indonesia
monsoon
Concluding Remarks
The climate will be warmer in future independent of
the scenario assumed. However, the degree of this
warming, particularly during the latter half of the
century, is determined by the strength of the scenario
pathway followed.
IPCC scientists have interpreted the increase in
climate variability and extreme weather events as
signals of the impacts of climate change due to global
warming. Whether these increases are due to global
warming as a result of anthropogenic activities of
mankind, or due to long term natural variability of
the climate itself, it is clear we need to take further
steps to better prepare ourselves against the impacts
of such changes.