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 June 2007, Putrajaya Marriott Hotel

SCOPE Introduction: - trends in climate variables - sea level - sea level - extreme weather - extreme weather Future Climate: - climate scenarios - climate projections Climate Variability: - El Nino - El Nino Concluding Remarks

Annual Temperature Trend for 1901 to 2005 (above) and 1979 to 2005 (below) Source: IPCC, 2007 Malaysia ~ 0.1 o C per Decade Peninsular Malaysia ~ 0.5 o C per Century

Source: IPCC, 2007 Annual Rainfall Trend for (above) and (below) DrierWetter Peninsular Malaysia ~ 3% per Decade

Changes in Temperature, Sea Level and Northern Hemisphere Snow Cover Relative to 1961–1990 Averages Source: IPCC, 2007 Increase in global average temperature, 100-year linear trend (1906 – 2005): 0.74 o C [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]

SEA LEVEL HAS RISEN BY METERS IN LAST CENTURY

Have tropical cyclones become more extreme?

Webster, Holland, Curry and Chang (2005) Cat. 4+5 Cat. 2+3 Cat. 1 Number of intense hurricanes has increased

How about smaller scale severe weather systems such as thunderstorms and tornadoes? Water Sprout at Kudat, 2006

Virtually certain: > 99% probability of occurrence Extremely likely: > 95% Very likely: > 90% Likely: > 66% More likely than not: > 50% Unlikely: < 33% Very unlikely: < 10% Extremely unlikely: < 5% 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 20 th century (typically post 1960) Likelihood of a human contribution to observed trend Warmer and fewer cold days and nights over most land areas Very likelyLikely Warmer and more frequent hot days and nights over most land areas Very likelyLikely (nights) Warmer spells / heat waves. Frequency increases over most land areas LikelyMore likely than not Heavy precipitation events. Frequency (or proportion of total rainfall from heavy falls) increases over most areas LikelyMore likely than not Area affected by droughts increases Likely in many regions since 1970s More likely than not Intense tropical cyclone activity increases Likely in many regions since 1970 More likely than not Increased incidence of extreme high sea level (excludes tsunamis) LikelyMore likely than not

Future Climate: - climate scenarios - climate projections - climate projections

Multi-model means of surface warming relative to 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 21 st century relative to the period 1980 – 1999, as calculated by multi- model averages for a low (B1), a medium (A1B) and a high SRES scenario for the decades (left) and (right). (IPCC, 2007)

Projected global average precipitation changes for the late 21 st century ( ) 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)

Smaller range in sea level rise compared to TAR because of improved information on uncertainties in the projected contributions c pared to TAR SEA LEVEL RSIES AT END OF 21 ST CENTURY

Phenomenon and direction of trend Likelihood of future trends based on projections for 21st century using SRES Scenarios Warmer and fewer cold days and nights over most land areas Virtually certain Warmer and more frequent hot days and nights over most land areas Virtually certain Warmer spells / heat waves. Frequency increases over most land areas Very likely Heavy precipitation events. Frequency (or proportion of total rainfall from heavy falls) increases over most areas Very Likely Area affected by droughts increases Likely Intense tropical cyclone activity increases Likely Increased incidence of extreme high sea level (excludes tsunamis) Likely Projections for Extreme Weather Events (IPCC, 2007)

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 21 st century

pH reduction between 0.14 to 0.35 units in the 21 st century adding to the present decrease of 0.1 units From pre-industrial times

Lightening caused fire at Pasir Gudang Port, Johore on 18 April 2006 Haze in Kuala Lumpur on 3 October 2006Flood in Kota Tinggi, Johore on 29 December Thunderstorm and Strong Winds at Subang Jaya, 9 Mac 2006 Abnormal weather in 2005 & 2006 – Is it due to Climate Change or Climate Variability?

Warmer winter & late onset Late onset of northeast monsoon Warmer sea surface temperature Late onset of Australia/Indonesia monsoon El-Nino - Warmer sea surface temperature These conditions had caused complex interaction within the atmosphere and ocean circulation system Late ending of tropical storm season Is it due to Climate Change or Climate Variability?

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.