Living With The Extremes

First Southeast Asia Workshop

Engineering for Climate Extremes Partnership

29 January 2018

Edwin S T Lai (黎守德)

Wet or Dry

Fog/Mist/Haze

Thunderstorms (tornadoes and hail)

Squall Lines

Rainstorms

Tropical Cyclones

Winter Storms

Heat Waves

Cold Spells

Climate Change

Connecting weather / climate events with potential risk

1.5°C vs 2°C world

Heat wave

Water resources

Extreme rainfall

Mean sea level rise

Food insecurity

Source: Schleussner et al (2016)3

Longer

Drier

Increased intensity

Higher

Reduction in crop yield in tropics

The Consequence of Global Warming

Enhance greenhouse effect Rising temperature

Thermal expansion of sea water & melting of snow on land

Sea level rise

Change in atmospheric circulation and enhanced water cycle

Regional differences in precipitation and more

frequent extreme weather and climate events

The Consequence of Global Warming

Enhance greenhouse effect Rising temperature

Thermal expansion of sea water & melting of snow on land

Sea level rise

Change in atmospheric circulation and enhanced water cycle

Regional differences in precipitation and more

frequent extreme weather and climate events

A brief overview of extreme weather and climate events

Extreme event is :

An integral part of the Earth’s climate system

An infrequent and/or unseasonal event which is significantly different from

"the norm" in terms of frequency, severity, duration and/or timing

Can have large regional and local variations in definition

May have significant impacts to various sectors of the society

Usually caused by a combination of factors – ranging from large scale

climate and weather systems to local weather interactions

Climate change will likely increase the frequency of occurrence and

severity of some extreme weather events (e.g. extreme temperatures,

rainstorm, flooding, severe typhoons, drought, etc).

Taking temperature as an example, the probability of

occurrence of a temperature usually follows a normal

distribution with a very low probability of occurrence

(usually less than 5%) for extremely high or lowtemperature.

Reported disasters in Asia (1970–2010)

Economic losses increase alongside with the increase in disaster number,

economic development, population growth and urbanization.

(Source : WMO No. 1123 - Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes (1970–2012))

Extreme weather and climate events in Hong Kong

• Extremely hot and cold weather

• Rainstorms and thunderstorms

• Drought

• Typhoons & storm surge

Past trends and future projections of

extreme weather and climate events in Hong Kong

Observed climate change in Hong Kong

Hong Kong climate projections in the 21st century

4°C world

2°C world

12

Record breaking temperature events in Hong Kong

33.8

34.3

34.8

35.3

35.8

36.3

36.8

1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

年最高氣溫

(攝氏度

)

An

nu

al m

axim

um

tem

per

atu

re (℃)

年份 Year

Record breaking temperature events in Hong Kong

1884: 33.9℃

1890: 34.3℃

1892, 1895, 1896: 34.4℃

1900: 36.1℃ 1990: 36.1℃

2015: 36.3℃

2017: 36.6℃

Record-breaking Events(since records began in 1884)

Date / Period New Record

Highest Monthly Mean Temperature for January

January 2017 18.5oC

Highest Monthly Mean Minimum Temperature for January

January 2017 17.0oC

Highest Daily Mean Temperature for July 30 July 2017 31.8oC*

Maximum Temperature 22 August 2017 36.6oC

Highest Monthly Mean Temperature for September

September 2017 29.0oC*

Highest Monthly Mean Minimum Temperature for September

September 2017 27.2oC

Highest Mean Temperature for Winter December 2016 to February 2017

18.4oC*

Highest Annual Number of Hot Nights** 2017 41 days

*tied highest record

**'Hot Night' refers to the condition with the daily minimum temperature equal to or higher than 28.0 degrees

Record-breaking high temperature events in 2017

RCP8.5High concentration scenario

RCP4.5Medium-low concentration scenario

Projected increase in very hot days and hot nights

in Hong Kong in the 21st Century

Hot nights - days with a minimum temperature of 28°C or above

Very hot days - days with a maximum temperature of 33°C or above

Icing due to freezing rain at Kadoorie Farm, Tai Po, on 24 January 2016

Ice pellets observed at Tai Mo Shan Radar Station on 24 January 2016

Icy and slippery roads at Tai Mo Shan on 24 January 2016, emergency services coming to the aid of trapped hikers at Tai Mo Shan

More frequent record breaking rainfall

Changes in the chance of rainfall extremes in the last century

Examples of extreme weather – Rainstorm on 16-18 June 1972

Po Shan Road

The persistence of the heavy rain during 16 to 18 June 1972 caused serious landslides at Pos

Shan Road of Hong Kong Island and Sau Mau Ping resettlement areas at Tsui Ping Road,

Kwun Tong, resulting in 150 deaths.

Sau Mau Ping

(Photo source : https://mmis.hkpl.gov.hk/kt_03)

(photo courtesy : GEO, CEDD)

Flooding of North Lantau Highway

(Photo courtesy of GEO)

24 hour rainfall distribution ending at 11:00am on 7 June 2008

Landslides in Tai O, Lantau

Examples of extreme weather – Rainstorm on 7 June 2008

The heavy downpour on the morning of 7 June brought a record breaking hourly rainfall of 145.5 mm at HKOHq.

(Photo courtesy : Sky Post and Ming Pao)

Examples of extreme weather –

Localized heavy rain on 7 October 2015 in Sai Kung

Future changes in extremely wet and extremely dry years in Hong

Kong under different greenhouse gas concentration scenarios

RCP8.5High concentration scenario

RCP4.5Medium-low concentration scenario

The total rainfall in Hong Kong in 1962 was only 1741 mm, well below the normal of about 2214 mm (1961-1990). The suitable became even worse in 1963 with a total rainfall of 901 mm, the lowest on record.

Long queue at a public standpipe, 1963

(Photo source : GRS and WSD)

Examples of extreme weather – The extreme drought in 1962-1964

Water rationing with water supply once every 4 days

A warming world that fuels the storms

Climate Change Possible effects Potential impacts

Warmer ocean Provide more energy for

storm development and

breed intense typhoons

Increase the risk of wind

damages

Warmer atmosphere Enhance the moisture-

holding capacity of the

lower atmosphere and

typhoon-induced rainfall

Increase the risk of

flooding and landslips

Sea level rise Make storm surge more

frequent and bring more

extreme sea levels

Increase the risk of

coastal flooding and

inundation damages

IPCC-AR5 (2013)

Tropical Cyclone MetricsI All TC frequencyII Cat 4-5 frequencyIII Lifetime Max IntensityIV Precipitation rate

Examples of extreme weather – Super Typhoon Hato in 2017

• Storm force winds in the Harbour

• Hurricane force winds over southern Hong Kong, e.g. Cheung Chau

• Extreme sea level due to storm surge of Hato coincided with astronomical high tide

Over 5,300 fallen trees

(Photo courtesy : Ray Kong)

Damages of curtain walls

(Photo courtesy : Kevin Campbell)

(Photo courtesy : GFS)

Vessels in distress

Siu Sai Wan(Photo courtesy:Charmaine Mok)

(Photo courtesy : Steve Lee)

Cheung Chau

(Photo courtesy : Remington Yu)

Coastal damage

Flooding by sea water

Video showing sea water flowing

into the underground car park

(Video courtesy : Godfrey Ho)

Sea water flowing into Heng Fa Chuen

(Video courtesy of Kitty Lam)

Recorded maximum sea level (mCD) and flood reports on 23 Aug 2017

(based on flood reports from government departments, news, and social media)

香港天文台 Hong Kong Observatory

海事處 Marine Department

由各部門負責管理的潮汐站Tide gauge managed by

渠務署 Drainage Services Department

機場管理局 Airport Authority

尖鼻咀Tsim Bei Tsui

大埔滘Tai Po Kau

高流灣Ko Lau Wan

橫瀾島Waglan Island

石壁Shek Pik

長洲Cheung Chau

馬灣Ma Wan

葵涌Kwai Chung

鰂魚涌Quarry Bay大澳

Tai O大廟灣

Tai Miu Wan

# Maximum water level derived from incomplete data

赤鱲角Chek Lap Kok

3.57

2.97#

4.56

3.43

4.09

3.56#

3.58

3.52

3.87

3.14#

3.29#

3.91

Macao

5.26 mCD(could be

5.6 mCD)

Hato Major Impacts – Storm Surge

Sub-hour to

Hours

Days Weeks Month Season Annual Decades Century

Site

District

Territory

-wide

Nowcasting&

Site specific forecasts

Weather forecasts(1-9 days) Extended outlook*, Seasonal forecast &

Annual outlookClimate projections

Various weather warnings

and advisories

Weather services time scale Climate services time scale

Weather and climate services in Hong Kong

- spatial and temporal coverage

* Extended outlook up to 14 days will be launched later in 2017

Severe weather and corresponding warning services in Hong Kong

High winds

TC warning signals

No. 1, 3, 8, 9 & 10

Strong Monsoon Signal

Extreme temperatures

Cold and Very Hot

warning

Frost warnings

Heavy rain

Color rainstorm

warning signals

Landslide warning

Special Announcement on

Flooding in the Northern NT

Thunderstorm warning

Dry conditions

Color fire danger warnings

Services, partnerships and stakeholder engagement

in the development of

RISK-BASED FORECASTS and IMPACT-BASED WARNINGS

The Global Framework for Climate Services (GFCS)

Five priority areas :

• Geotechincal Engineering Office

• Drainage Services Department

• Transport Department

• Home Affairs Department

• Education Bureau

• Hong Kong Examination & Assessment

Authority

• Security Bureau

• Review existing procedures

• Propose new initiatives or requirements

• Update contact list

• Promote better working relationship

• Arranging Communication Exercise /

Drill

• Outlook for the year: e.g. No. of TCs,

annual rainfall, etc

Liaison Meetings with Government Departments

before Typhoon & Rain Season

DRR and Contingency PlanningDrill and exercise

on 24 July 2017

Live action during Hato on 23 August 2017(photo courtesy of Civil Aid Service).

(photo courtesy of the Information Services Department)

Summary

Learn from the past, different extreme weather events can happen in

Hong Kong and result in significant impacts to our society, particularly

for vulnerable groups and in vulnerable areas .

Against the background of climate change and local urbanization, Hong

Kong will expect even warmer weather, more variable rainfall, and a

sea level that keeps rising in the coming centuries. This may affect the

frequency and severity of various extreme weather and increase the

risk of related impacts.

To prepare for the future, what is adequate today may not be good

enough in the foreseeable future. We should not be complacent but

raise public awareness on natural disaster preparedness and make a

concerted effort to take appropriate measures to ensure Hong Kong’s

safe and sustainable development, not only now but for the generations

to come.

The Frog in the Pot

The change is too trivial to be of serious threat

The change is gradual enough to react

The change is not going to happen here

The change is far too distant in the future to be of my concern

The Frog in the Pot

The change is too trivial to be of serious threat

The change is gradual enough to react

The change is not going to happen here

The change is far too distant in the future to be of my concern

未雨綢繆 Preparing for a rainy day - recognizing near and present

danger is the key to good planning for a clear and pleasant future!

THANK YOU