3. Global weirding –
The weather gets weird. The hots are expected to get hotter, the wets
wetter, the dries drier and the most violent storms more numerous.
3
12. Selection of record-breaking meteorological events since
2000, and the confidence level that the event can be
attributed to climate change.
12
13. Basic concepts of climate change impact
Climate change impacts
1st order : temperature rise, precipitation shift;
2nd order : sea level rise, increase in vector population, health, hill
fire …
3rd order : coastal erosion, impact to ecosystem, food production…;
impacts are the “damage report” of climate change.
Vulnerability : exposure (magnitude, timing, distribution, persistence,
likelihood of impacts, climate dynamics) + sensitivity (effect as a function
of the magnitude of change; a mixed issue – natural and social) +
adaptive capacity, largely social issues, except for ecosystems);
IPCC definition: vulnerability is the degree to which a system is
susceptible to, or unable to cope with, adverse effects of climate change,
and variability and extremes. Vulnerability is a function of the character,
magnitude and rate of climate change and variation to which a system is
exposed, its sensitivity, and its adaptive capacity.
Resilience in natural and human systems : ability to return to a healthy
state following a change or shock.
13
25. Impact to HK
Health - Dengue fever
Ovitrap (誘蚊產卵器 ) provides data to
study conditions favourable for
reproduction
白紋伊蚊 (Aedes albopictus)
Ovitrap Index =
No. of Aedes-positive ovitraps /
No. of ovitraps collected from the
specific area x 100%
25
29. Φ =eaT (bR2 + cR + d)
Φ :ovitrap index
T: mean temperature from D-15
to D+6
R: total rainfall from D-15 to D-1
a, b, c, d : constants
Mathematical model for ovitrap index
29
•Air temperature and rainfall are the most important parameters.
•Relative humidity is also correlated, but is considered a secondary
parameter to temperature and rainfall.
•Wind strength/direction affects distribution.
42. Decrease in productivity
Natural disasters - floods, tropical
storms, drought are on the increase
In many countries, climate change is
exacerbating already adverse natural
conditions.
Increasingly, the world's fertile
farmland is under threat from erosion,
salination and desertification.
Deforestation by human accelerates
the erosion of land.
42
43. US sweet corn failure, 2012;
Popcorn prices soared from $20
per 50-pound bag to $30 and
higher.
43
52. Food Security in China – if no effective measures are taken, agricultural
production in China may decrease by 5 – 10%, with the three main crops
suffering reduction in production (causes: rising temperature, more frequency
drought/flood, water shortage etc.)
Wheat Rice Corn
52
53. National relative yield loss (%) in 2030 (B1
scenario) for (a) soybean, (b) maize and (c)
wheat as a result of O3 increases
53
54. Projected impact of climate change on
agricultural yield (compared to 2003 levels)
54
Source: European Environment Agency
58. Monsoons - not the same worldwide
American southwest – medieval drought (dust bowl was a picnic
compared with the drought that cause the demise of Mayan
civilization)
China highlands - drier
South Asian monsoon - dry spells increase in frequency and wet
spells increase in intensity (Nature Climate Change, 2014) –
although there is yet no consensus.
58
Fig. Change in the mean annual range of precipitation: 1976 to 2003 minus 1948 to
1975 periods (mm per day). Blue/green (red/yellow) colour denotes a decreasing
(increasing) annual range of the monsoon rainfall. Grey areas indicate missing values
(oceans) or areas with insignificant annual changes. IPCC AR4, 2007
60. Hong Kong situation - rainfall, water
collected, water imported (1965 – 2012)
Source: Civic Exchange, http://www.civic-exchange.org/wp/wp-content/uploads/2013/07/201307LiquidAssets4_en.pdf
60
61. 19
63
SPI of Heyuan (河源)
SPI of Hong Kong
1963
The drought has now spread, far across this wasteland, the few now left undead,
crawl on the burning sand. The river's dry, the mortals die, it's doomsday's dawn.
61
65. Impact to ecosystem – an example
Coral reef
Hot spot of biodiversity
Support 500 million people.
< 0.5% of global ocean
US10 billion/year
65
Coral reef symbiosis
(algae and coral) :
coral gains oxygen
and extra energy for
growth, algae gains
carbon dioxide and
protection
69. Impacts to ocean (Upper : ocean acidification;
Lower: “sea-butterfly in 2100 seawater”)
69
70. Impacts to Aquatic ecosystem
Increasing temperature leads to coral reef bleaching;
Ocean acidification;
Range shifts of fish related to temperature changes;
Movement of phankton due to salinity changes;
Changes in pathogen and invasive species abundance;
Fish migration in lakes and rivers;
Decrease diatom abundance;
Salinity and temperature changes may shift planetary-
scale ocean circulation.
70
71. Impacts of ecosystem
The resilience of many ecosystems is likely to be exceeded by an
unprecedented combination of climate change and its associated
disturbances (flooding, drought, wildfire, insects, ocean
acidification etc) and other drivers such as land-use change,
pollution and over-exploitation of resources – multiple exposure
20 – 30% of plant/animal species at increasing risk of extinction
Shifting climate zones
Vegetation don’t shift quickly, but insects move quickly – a
mismatch
Some positive impacts likely (carbon fertilization), but outweighed
by extensive forest and woodland decline through wildfire, insects
etc.
71
72. Impacts on terrestrial systems
Extinction of many amphibian species
Shifting timing of events and geographical range
Increasing growth in some forests, but also
surging pest populations
coastal erosion
marshland degradation
72
76. Impact to HK
Economy – eco-
tourism
Potential loss in coastal wetland and damage of mangrove habitat as sea level
rises (eroding the outer boundary of wetland, inland retreat of mangrove is
prohibited by artificial structures) – loss of migratory birds;
Emigration of Chinese Dolphin ?;
Less diversified flora (trees shifting upward and northward; increase in more
invasive species) - negative impact to country park and hiking industry;
76
77. Impact to HK
Economy – fishing industry
• Toxic algae bloom ( warm
temperature, heavy rainfall flushing
phosphorus fertilizer to sea…);
• Loss of diversity and changes to
fish community composition as a
result of coral bleaching;
• Coral-dependent fishes suffer
the most rapid population declines
as coral is lost;
• Other species will exhibit long-
term declines due to loss of
settlement habitat and erosion of
habitat structural complexity;
• Increased ocean temperature
will affect the physiological
performance and behaviour of
coral reef fishes.
Martin Williams, 2011,
Cheung Chau
77
79. Typhoon Hagupit passed about 180 km SSW of HK
and brought a storm surge of 1.4 m at Victoria
Harbour, raising the sea level to a height of 3.53 m
above Chart Datum (2nd highest after Typhoon
Wanda)
79
80. IPCC Assessment Report No. 5 projects that in the last decades of 21st
century, global sea level rises by 0.26-0.82m
Return period (yr)
Extreme sea level above chart datum (m)
With current sea
level
Mean sea level rises
by 0.26m
Mean sea level rises
by 0.82m
2 2.9 3.2 3.7
5 3.1 3.4 3.9
10 3.3 3.5 4.1
20 3.4 3.6 4.2
50 3.5 3.8 4.4
Storm surge from typhoons
Storm surge risks increase with sea level rise
Hagupit (50 yr event) becomes an annual/biennial event
82. How humans become exposed to waterborne
diseases following inundation
82
US Climate Assessment Report 2013
83. Impact to HK
Infrastructure - Wastewater and sewage
Rising sea level puts pressure on drainage
systems – makes waste water and storm
water harder to be discharged to the sea,
and result in flooding;
Putting HK’s drainage system under
pressure.
83
84. Effect on weather systems
More water vapour – the “nitro” of the
atmosphere - heat engine
More stormy
84
85. Typhoons and hurricanes
Warmer sea surface – more powerful, not necessarily more storms
Complicated - warmer atmosphere may negate the effect of warmer sea surface.
Super typhoon Haiyan
85
Fig.
Expected
percent
change in
the
average
over period
2081–2100
relative to
2000–2019
(AR5)
87. Key vulnerabilities of cities
Concentrated population
Urban heat island effect
Infectious diseases
Massive investment in infrastructure
Hurricane Katrina and Sandy in US
Insured losses
Disconnect between people and food source
Often centralized system of energy provision, fresh water
resources etc.
Ripple effects
Climate refugees – Stern Review estimates 170 million people displaced
by flooding at 3 deg warming, and 300 million more at 4 deg.
87
96. Infrastructure - Increased costs for
building construction and maintenance
New building and engineering standards
(e.g. subsidence control, drainage);
More durable materials (higher
temperature and severe rainfall);
Utilities vulnerable to extreme weather;
Higher insurance costs;
96
97. References
The impacts of climate change in Hong Kong and the Pearl River
Delta, Civic Exchange, 2006
Final report submitted to EPD on “Provision of Service for
Charactering the Climate Change Impact in Hong Kong”,
Department of Civil & Structural Engineering, HK Polytechnic
University, 2004
Hong Kong Observatory website:
http://www.hko.gov.hk/climate_change/publication_hko_e.htm
Stern Review: The Economics of Climate change:
http://mudancasclimaticas.cptec.inpe.br/~rmclima/pdfs/destaq
ues/sternreview_report_complete.pdf
97
