Download Climate change in a nutshell

HONG KONG IN A
WARMING WORLD
SECOND EDITION
THE WORLD
Contents
THE WORLD
1 Unprecedented carbon dioxide concentration........................ 2
2 Abrupt temperature rise...................................................... 3
THE WORLD
3 Melting of ice and snow...................................................... 4
4 Mean sea level rise............................................................ 5
5 More extreme heat............................................................. 6
6 Enhanced water cycle......................................................... 6
7 Projection of global climate for the 21st century..................... 7
HONG KONG
8 Climate change in Hong Kong........................................... 12
9 Projection of Hong Kong climate for the 21st century............15
Mitigating climate change – our role and responsibilities.......21
10
Adapting to climate change – be prepared.......................... 23
11
Collaborative effort in combating climate change................. 25
12
Useful links.......................................................................... 27
Appendix............................................................................. 28
Source of figures and data..................................................... 29
Photo credits........................................................................ 29
Warming of the climate system is
unequivocal, and since the 1950s,
many of the observed changes are
unprecedented over decades to
millennia.
It is extremely likely that human
influence has been the dominant
cause of the observed warming
since the mid-20th century.
The Fifth Assessment Report (AR5) of
Working Group I of the Intergovernmental
Panel on Climate Change (IPCC)
1
THE WORLD
1
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Unprecedented carbon dioxide
concentration
2
The atmospheric concentration of carbon dioxide (CO2), the most
important greenhouse gas as well as the main driver of global climate
change in the last century, has increased by over 40 per cent since
pre-industrial times. The increase is primarily due to burning of fossil
fuels and secondarily due to deforestation. Present-day concentration
of CO2 is the highest in the last 800,000 years.
FIGURE 1 Highest in the last
8OO,OOO years
350
FIGURE 2 Warming trend during
1901-2012
the warmest
since 185O.
4O%+
400
With heat trapped by the increasing presence of greenhouse gases,
almost every corner of the globe has experienced a warming trend
throughout the 20th century.
The first decade of the
21st century has been
Atmospheric carbon dioxide concentration in the last 800,000 years
ppm
Abrupt temperature rise
(OC)
The recent warming is so
abrupt that it has totally
reversed the long-term cooling
trend in the last 5,000 years.
FIGURE 3 Global temperature anomalies
with respect to 1961-1990
300
O
C
0.8
250
0.4
200
0
150
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
-0.4
uncertainty
average
-0.8
-1.2
10,000
Check the latest
atmospheric CO2
levels here:
2
8,000
6,000
4,000
2,000
0 number of years
before 1950
Latest global
average surface
temperature
anomaly relative
to 1951-1980:
3
THE WORLD
THE WORLD
3 Melting of ice and snow
The warming climate has contributed
to widespread melting of snow cover,
ice caps, mountain glaciers and ice
sheets over Greenland and West
Antarctica. Reduction of reflective
surfaces of ice and snow will in turn
mean more heat absorbed as the
Earth’s ability to disperse sunlight
back to space is compromised. This is
expected to accelerate the melting of
ice and snow – a vicious cycle.
4
FIGURE 4 Arctic sea ice decrease from
1980 (upper) to 2012 (lower)
Mean sea level rise
Thermal expansion of sea water and melting of land-based ice and
snow will lead to a global sea level rise. The rate of sea level rise since
the mid-19th century has apparently accelerated when compared to the
mean rate in the previous two millennia.
FIGURE 5 198O
Global average sea level change
relative to 1900-1905
mm
200
2O12
150
100
50
MUIR GLACIER , ALASKA
Different coloured lines represent
different independent data sets
0
-50
1900
1941
1920
1940
2OO4
4
Latest
Arctic sea
ice extent:
Latest
glacier
mass
balance:
Mass variation
of Antarctic
and Greenland
Ice Sheets:
1980
2000
year
Rising sea level
will cause coastal
flooding and
accentuate the
threat of storm
surges brought
by cyclones.
Melting of Muir Glacier, Alaska’s Glacier Bay from 1941 (left) to 2004 (right)
Short video
on the largest
Greenland
glacier calving
ever filmed:
1960
Storm surge caused by Hurricane Sandy along the east
coast of the United States in 2012
Latest
sea level
change:
5
THE WORLD
5
THE WORLD
7
More extreme heat
A warming climate increases the chance of extreme heat. The number
of cold days and nights has decreased and the number of warm days
and nights has increased on the global scale.
27 December 2013 - 3 January 2014
The frequency of
heat waves has
increased in many
parts of Europe,
Asia and Australia.
6
0
TEMPERATURE
The world moved along the trajectory of a high greenhouse gas
concentration pathway in the past decade. Although implementation
of the pledges of targets for emission reduction by 2030 made by
countries attending the Paris climate summit (COP21) in 2015 could
steer the world away from the worst scenario, it is evident that based
on the climate projections by IPCC AR5, much more effort will be
required from now on if we aim to reach the COP21 target of keeping
global temperature rise below 2ºC (relative to pre-industrial levels) by
the end of this century.
FIGURE 6 Land surface temperature anomaly over Australia
≤-15
Projection of global climate for
the 21st century
Much more effort
required to keep
global temperature
rise below 2ºC
≥15 (oC)
Enhanced water cycle
Ocean warming leads to more evaporation of sea water. A warmer
atmosphere has the capacity to hold more water vapour, thereby
increasing the chance of heavy rain.
More land
areas have
experienced an
increase in heavy
precipitation
since the mid20th century.
COP 21, Paris
Based on the pledges made at COP21, the world could still be heading
towards a temperature rise of around 3°C (relative to pre-industrial levels)
by the end of this century. It is virtually certain that there will be more
hot temperature extremes and fewer cold temperature extremes over
most land areas as global mean temperature increases. Heat waves
will occur with a higher frequency and
duration despite the occasional episodes of
cold winter extremes.
Heavy rain in Shenzhen on 11 May 2014
6
7
THE WORLD
THE WORLD
PRECIPITATION
FIGURE 7 Carbon dioxide emissions associated with different
greenhouse gas concentration scenarios
billion
tonne/year
High
100
80
Worst
scenario
Country pledges
for 2030
60
FIGURE 9 Medium-high
2015
40
20
0
In a warmer world, extreme precipitation events will very likely become
more intense and more frequent over most of the mid-latitude land
masses and over wet tropical regions by the end of this century.
Projected percentage change in 20-year return values of annual maximum
daily precipitation for 2081-2100 per unit local temperature increase (°C)
relative to 1986-2005
Medium-low
Historical
observations
2ºC target
scenario
Extreme
precipitation
events will very
likely become
more intense and
more frequent.
Low
-20
1980
2000
2020
2040
2060
2080
2100
year
FIGURE 8 Projected regional temperature change (°C) for 2081-2100 per unit
global average temperature increase (°C)
relative to 1986-2005
FIGURE 1O Projected percentage change in global average annual maximum
5-day precipitation over land regions for different greenhouse gas
concentration scenarios
relative to 1981-2000
% relative change
Historical simulation (up to 2005)
Low
Medium-low
High
20
15
10
5
ºC per ºC increase in global mean
0
-5
8
1960
1980
2000
2020
2040
2060
2080
2100 year
9
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THE WORLD
DROUGHT
The risk of drought remains in many parts of the world with substantial
increases in soil dryness projected in the Mediterranean, Europe,
North and South Americas, southern Africa and China.
FIGURE 11 Projected changes in annual mean surface soil moisture in 2081-2100
relative to 1986-2005
Low concentration scenario
HONG KONG
High concentration scenario
(mm)
SEA LEVEL
In a warmer world, most of the coastline will be affected by sea level rise.
Even for the medium-low and medium-high greenhouse gas concentration
scenarios, which are the more likely scenarios after COP21, the impact of
sea level rise on coastal communities will still be significant.
Hong Kong is not immune
to climate change.
FIGURE 12 Projected global mean sea level rise
relative to 1986-2005
m
1.0
0.8
0.6
High concentration scenario
Median
Likely range
Low concentration scenario
Median
Likely range
0.4
0.2
0
2000
10
2020
2040
2060
2080
2100
year
Projected
regional
mean sea
level rise for
2081-2100:
11
HONG KONG
HONG KONG
8 Climate change in Hong Kong
FIGURE 14 Changes in the annual number of hot nights,
very hot days and cold days
TEMPERATURE
40
th
Since the late 19 century, Hong Kong has experienced a significant
warming trend. Both global warming and effects of local urbanization
contribute to the warming, with the latter estimated to contribute up to
50% of the warming.
30
More frequent
Annual number of hot nights
Annual number of very hot days
Annual number of cold days
10
0
FIGURE 13 Rarer
20
1885-1914
1986-2015
Annual mean temperature recorded at the Hong Kong Observatory
headquarters (1885-2015)
Data are not available from 1940 to 1946
ºC
24.5
24.0
PRECIPITATION
A significant
warming trend
Extreme precipitation events have become more frequent. The hourly
rainfall record at the Hong Kong Observatory headquarters was broken
several times in the last few decades, whereas it used to take several
decades to break the record in the past.
23.5
23.0
More frequent
extreme
precipitation
FIGURE 15 22.5
Hourly rainfall records (1885-2015)
22.0
mm
160
21.5
2008: 145.5mm
140
21.0
1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
1885-2015 +0.12 °C/decade
1986-2015 +0.17 °C/decade
year
2006: 115.1mm
120
1966: 108.2mm
1992: 109.9mm
1926: 100.7mm
100
1886: 88.4mm
80
Over the last century, the number of hot nights (daily minimum
temperature ≥ 28ºC) and very hot days (daily maximum temperature ≥
33ºC) in Hong Kong has increased by manifold while the number of cold
days (daily minimum temperature ≤ 12ºC) has decreased significantly.
12
60
1880 1890 1900 1910 1920 1930 1940 1950
1960 1970 1980 1990 2000 2010 year
Latest
temperature
trend in Hong
Kong:
Trends in
extreme
weather
events in
Hong Kong:
13
HONG KONG
HONG KONG
of Hong Kong climate for
9 Projection
st
the 21 century
SEA LEVEL
Tide gauge records in Victoria Harbour
since 1954 show an unambiguous rise of
mean sea level.
TEMPERATURE
If the emission reductions agreed at COP21 materialize, the mediumlow to medium-high greenhouse gas concentration scenarios would be
more likely than the other two scenarios. In such cases, a rise of 1.5 to
3.5°C (relative to 1986-2005) in the decade of 2091-2100 is expected.
FIGURE 16 Annual mean sea level at Victoria Harbour
Sea level above
Chart Datum (m)
1.6
1.5
1954-2015
+30 mm/decade
FIGURE 17 1.4
Projected changes in the annual temperature of Hong Kong
under different greenhouse gas concentration scenarios
1.3
relative to 1986-2005
1.2
ºC
Annual mean
temperature
6
5
1.0
1950
1960
1970
1980
1990
2000
2010
year
in 2091-2100
4
Medium-high
Medium-low
3
Latest trend
in mean sea
level in Hong
Kong:
High
1.5-3.5ºC
1.1
10-year average
temperature anomaly
2
Low
1
likely range for
2091-2100
0
-1
2000
2010
2020
Observed
High
Medium-high
14
2030
2040
2050
2060
2070
2080
2090
2100 year
Medium-low
Low
15
HONG KONG
HONG KONG
Even under the medium-low and medium-high greenhouse gas
concentration scenarios, the annual numbers of hot nights and very hot
days are expected to continue rising significantly in the 21st century,
while the annual number of cold days is expected to drop.
12
FIGURE 18 Projected annual number of hot nights, very hot days
and cold days in Hong Kong under the medium-low
and high greenhouse gas concentration scenarios
160
FIGURE 19 Future changes in extremely wet and extremely dry
years under the medium-low and high greenhouse gas
concentration scenarios
160
Observed
160
Mediumlow
120
120
120
80
80
80
40
40
40
0
0
1986-2005
High
2091-2100
Mediumlow
12
12
8
8
8
4
4
4
0
1885-2005
0
2006-2100
2051-2060
Annual number of hot nights
Annual number of very hot days
Annual number of cold days
2091-2100
year
Projection of
hot nights, very
hot days and
cold days for all
scenarios:
0
2006-2100
year
The year-to-year and decade-to-decade variations of rainfall will remain
large. However, as temperature continues to increase in the 21st century,
extreme rainfall is also expected to increase.
FIGURE 2O Projected annual maximum daily rainfall and annual
Extreme rainfall
maximum 3-day rainfall in Hong Kong under the medium- expected to
increase
low and high greenhouse gas concentration scenarios
mm
mm
600
PRECIPITATION
Except for the low greenhouse gas concentration scenario, the annual
rainfall is expected to generally increase towards the end of this
century. Of even more interest is the remarkable increase in extremely
wet years (annual rainfall > 3168 mm) in 2006-2100 for all the
scenarios while the number of extremely dry years (annual rainfall
< 1289 mm) is expected to remain about the same.
Observed
600
mm
Mediumlow
600
400
400
400
200
200
200
0
1986-2005
0
2051-2060
2091-2100
0
High
2051-2060
Annual maximum daily rainfall
Annual maximum 3-day rainfall
Projection of
extremely wet
and extremely
dry years for all
scenarios:
16
High
Extremely wet years
Extremely dry years
0
2051-2060
Observed
Remarkable
increase in
extremely
wet years
2091-2100
year
Extreme
rainfall
projection for
all scenarios:
17
HONG KONG
HONG KONG
SEA LEVEL
STORM SURGE
Regardless of the greenhouse gas concentration scenario, the mean sea
level in Hong Kong and its adjacent waters is expected to rise further in
the 21st century.
Apart from high winds and heavy rain, storm surge is also a threat
posed by approaching tropical cyclones. Over the last hundred years
or so, several typhoons (e.g. in 1874, 1906, 1937 and 1962) had
brought severe storm surges to Hong Kong, causing heavy casualties and
damages.
FIGURE 21 Projected changes in the mean sea level in Hong Kong and its adjacent
waters under different greenhouse gas concentration scenarios
relative to 1986-2005
Mean sea level
expected to rise
further
m
1.2
High
1.0
Medium-high
Medium-low
Low
0.8
Damages to ships and piers at Central, Hong
Kong Island, brought by severe storm surge
during the great typhoon of 1874.
Sea waves bombarding the coast of Central, Hong
Kong Island, during the great typhoon of 1906
which caused a death toll of more than 10,000.
0.6
10-year average
sea level change
0.4
likely range for
2091-2100
0.2
0
2000
2010
2020
Observed
High
Medium-high
2030
2040
2050
2060
2070
2080
2090
2100
year
Medium-low
Low
With a warming climate, the mean sea level in Hong Kong and its
adjacent waters is expected to continue rising for the rest of the 21st
century, and the threat of storm surges brought by tropical cyclones will
correspondingly increase. A sea level of 3.5 m that can cause serious
flooding in certain low-lying areas in Hong Kong, such as the one
brought by Typhoon Hagupit in 2008, is a 1-in-50 year event today.
It would however become a 1-in-5 year to 1-in-10 year event by 20212040 and an annual event by the end of the 21st century if the high
ends of the sea level rise projections materialize.
Projection
data of mean
sea level in
Hong Kong:
The threat of storm
surges brought by
tropical cyclones will
increase with rising
sea level.
Severe flooding in Tai O during the
passage of Typhoon Hagupit in 2008
18
Storm surge
damages
by Typhoon
Wanda in
1962:
19
HONG KONG
HONG KONG
Storm surge and high waves
caused by tropical cyclone
Mean Sea Level
Chart Datum
Increased threat of storm surges
with a higher mean sea level
Mean Sea Level
1O Mitigating climate change –
our role and responsibilities
Just as mankind has played an undeniable role in bringing about climate
change, we have an inescapable responsibility in mitigating the impact
so caused. While some of the changes that are already taking place may
not be reversible, the scenario-based projections as described in IPCC
AR5 do provide some hope for steering the future course of events and
hence mitigating the overall impact to a certain extent.
FIGURE 22 Greenhouse gas emissions in Hong Kong by sector in 2012
Electricity generation
is the major source
of emissions.
68.2%
Total
Chart Datum
43.1
MILLION
TONNES
17.1%
Electricity
generation
Transport
CO2 equivalent
5.4%
3.9%
0.1%
5.3%
Waste
Other end use
of fuel
Industrial
processes and
product use
Agriculture,
forestry and
other land use
20
21
HONG KONG
HONG KONG
11
Adapting to climate change –
be prepared
Global temperature rise by the end of the 21st century is likely
to be around 3ºC (relative to pre-industrial levels) even with full
implementation of COP21 countries’ pledges. While we should make
every effort to reduce greenhouse gas emissions, we also need to be
prepared for the impacts of a warmer world, such as more extreme
heat, more extreme rainfall and higher sea level.
Save energy and water
Use energy-efficient products
and switch them off when not
needed
Adopt a low-carbon and
pro-green
lifestyle
FIGURE 23 Integrating thermal load and wind information in urban planning
Drive less and
drive smart
Reduce waste
and recycle
Whatever the governments of this world pledged in COP21, ultimately it
is down to us as citizens of the planet to achieve the targets set through
a change in mindset, lifestyle and consumption behaviour. And we need
to act conscientiously, collectively and with urgency. We should also
spread the word around, promote such awareness among the younger
generations, and pursue societal actions in support of sustainable efforts
in meeting the long-running challenges of climate change.
Energy
saving
tips:
22
Water
saving tips:
23
HONG KONG
HONG KONG
FIGURE 24 Building infrastructure to reduce urban flood risk
during heavy rain events
12 Collaborative effort in combating
climate change
The Hong Kong Observatory supports the Global Framework for Climate
Services – an international initiative launched by the World Meteorological
Organization to enhance and extend the effective use of scientificallybased climate information to cope with climate variability and climate
change in the five priority areas of energy, agriculture and food security,
water, health and disaster risk reduction. The Observatory has been
collaborating with partners and stakeholders in such efforts over a wide
range of issues:
With government
bureaux and
departments to
promote public
awareness of
climate change
Constructing check dam to
prevent debris flow
Strengthening
coastal protection
24
With Radio Television Hong
Kong to spread the messages
about climate change
With the utility sector to encourage behavioural
changes in mitigating climate change
With the academia in conducting
climate research
Production of
videos on tropical
cyclone hazards
which were shown
at the Third United
Nations World
Conference on
Disaster Risk
Reduction at
Sendai, Japan in
2015:
With Education Bureau
to produce special
educational television
programmes on climate
change
Projection of
rainfall and
Standardized
Precipitation
Index submitted
to the Hong
Kong/Guangdong
Joint Liaison
Group on
Combating
Climate Change:
25
HONG KONG
HONG KONG
The Observatory provides scientific input to climate change documents
in Hong Kong, such as the Hong Kong Climate Change Report 2015
and Hong Kong Climate Resilience Roadmap for Business, and actively
supports the policies and actions in climate mitigation, adaptation and
resilience undertaken and coordinated by the government's high-level
Steering Committee on Climate Change. The Observatory facilitates
stakeholders and decision-makers in the planning and implementation of
adaptation measures based on the latest assessment of climate trends
and projections. In view of the likelihood of more frequent extreme
weather as a result of climate change, the Observatory through its
forecasting and warning services, as well as its public education activities
in collaboration with partners on specific issues such as landslips and
urban flooding, also contributes to disaster risk reduction efforts to
enhance the community’s preparedness
and resilience against the threats of natural
The Observatory actively supports
hazards. Such collaboration extends to
the policies and actions in climate
school talks and other outreach initiatives
on thematic topics such as energy saving
and
and biodiversity conservation for the
mitigation of climate change.
mitigation, adaptation
resilience.
Useful links
• Hong Kong Observatory Climate Change Webpage
www.weather.gov.hk/climate_change/climate_change_e.htm
• The Fifth Assessment Report of IPCC Working Group I
www.ipcc.ch/report/ar5/wg1
• Environmental Protection Department Climate Change Webpage
www.epd.gov.hk/epd/english/climate_change
• Council for Sustainable Development
www.susdev.gov.hk/html/en/council
• Environmental Campaign Committee
www.ecc.org.hk/english/index.html
• The 21st Conference of the Parties to the United Nations Framework Convention on Climate Change
www.cop21.gouv.fr/en
Joint school talks with partners
Director of the Observatory giving a speech at
the launch of the Hong Kong Climate Change
Report 2015
Production of YouTube videos
to promote public awareness
26
Hong Kong
Climate
Change
Report 2015:
Hong Kong
Climate
Resilience
Roadmap for
Business:
27
HONG KONG
Appendix
Source of figures and data
FIGURE 25 Projected annual mean surface temperature change from the period 1986-2005 to
2081-2100 under the low (upper left), medium-low (upper right), medium-high
(lower left) and high (lower right) greenhouse gas concentration scenarios.
Figure 1: World Meteorological Organization
Figures 2, 5, 8-12, 25 and Table 1: Intergovernmental Panel on Climate Change
Figure 3: A Reconstruction of Regional and Global Temperature for the Past 11,300 Years. Shaun A.
Marcott et al. Science 339, 1198 (2013); DOI: 10.1126/science.1228026.
Figures 4 and 6:
US National Aeronautics and Space Administration
Figure 7:
Global Carbon Project
Figures 13-21:
Hong Kong Observatory
Figure 22:
Data from Environmental Protection Department
Figure 23:
Planning Department
Figure 24:
Environment Bureau
Photo credits
TABLE 1 Projected changes in global mean surface temperature and global mean sea level rise for
the mid- and late 21st century under different greenhouse gas concentration scenarios
relative to 1986-2005
2046-2065
Global mean
surface temperature
change (ºC)
Greenhouse gas
concentration scenario
Low
Medium-low
Medium-high
High
Global mean sea
level rise (m)
28
Greenhouse gas
concentration scenario
Low
Medium-low
Medium-high
High
U. W. O. Field, B. F. Molnia, US National Snow and Ice Data Center (Melting of
Muir Glacier, Alaska's Glacier Bay from 1941 to 2004)
P.5
Mark C. Olsen, US Air Force (Storm surge caused by Hurricane Sandy along the
east coast of the United States in 2012)
P.6
weibo.com/szmb (Heavy rain in Shenzhen on 11 May 2014)
P.7
The secretariat of the United Nations Framework Convention on Climate Change
(COP21, Paris)
P.19
Mr Shun Chi-ming (Damages to ships and piers at Central, Hong Kong Island,
brought by severe storm surge during the great typhoon of 1874. Sea waves
bombarding the coast of Central, Hong Kong Island, during the great typhoon of
1906 which caused a death toll of more than 10,000.)
P.19
Television Broadcasts Limited (Severe flooding in Tai O during the passage of
Typhoon Hagupit in 2008)
P.24
Civil Engineering and Development Department (Constructing check dam to
prevent debris flow. Strengthening coastal protection.)
P.25
Radio Television Hong Kong (Poster of “Meteorology Series IV”)
2081-2100
Mean
Likely range
Mean
Likely range
1.0
1.4
1.3
2.0
0.4 - 1.6
0.9 - 2.0
0.8 - 1.8
1.4 - 2.6
1.0
1.8
2.2
3.7
0.3 - 1.7
1.1 - 2.6
1.4 - 3.1
2.6 - 4.8
2046-2065
P.4
2081-2100
Mean
Likely range
Mean
Likely range
0.24
0.26
0.25
0.30
0.17 - 0.32
0.19 - 0.33
0.18 - 0.32
0.22 - 0.38
0.40
0.47
0.48
0.63
0.26 - 0.55
0.32 - 0.63
0.33 - 0.63
0.45 - 0.82
29
Published by the Hong Kong Observatory
The Government of the Hong Kong Special Administrative Region
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