Climate Change Teacher Professional Development Programme26 Feb 2011

Climate Change Teacher Professional Development Programme26 Feb 2011

An Introduction to Climate Change淺談氣候變化

T C LeeHong Kong Observatory

Content

• A brief overview of global climate change

• Climate change in Hong Kong

• Potential impacts

• Climate change : The debate and challenges

What is Climate ? What is Weather ?

“Climate is what you expect; weather is what you get.”by Robert A. Heinlein

• Weather is the day-to-day state of the atmosphere

• Climate describes the long-term character of all weather variations -- the ‘expected’ weather

• Climate ≈ average of weather

The changing climate

• While climate represents the average of the changing weather (short term), it is also changing in a long term perspective (centuries or longer).

• The causes of the changing climate is very complex, involving both natural and human-induced factors. Many studies are still carrying out to understand and explain the changes in the past and project what will happen in the future.

Records of Northern Hemisphere temperature variation during the last 1300 years with 12 reconstructions using multiple climate proxy records (tree rings, boreholes, ice core/ice boreholes, etc.) shown in colour and instrumental records shown in black. (Source IPCC AR4)

The late 20th century is likely the warmest period the Earth has seen in at least 1000 years.

2010 equals record for world’s warmest year

(Source : WMO, http://www.wmo.int/pages/mediacentre/press_releases/pr_906_en.html)

What makes the climate change ?

What are the main causes of the temperature rise since mid-20th century ?

Main contributors to climate change

• Solar activities

• Earth’s orbital shift

• Volcanic activities and plate tectonics (continental drift)

• Climate internal variability (ocean and atmosphere)

• Atmospheric chemical composition - Greenhouse gases and aerosols (natural or anthropogenic)

Human induced

Complexity of Earth’s Climate

(source : IPCC, AR4)

Condition for no greenhouse gas in the atmosphere

visible

infra-red

earth

sun

Heating = Heat DissipationSurface temperature ≈ -18 oC

Greenhouse Effect

greenhouse gases

partly absorbed

re-emitted infra-red

sun

earth

visible

infra-redAverage Temperature about 15℃

Heat-trapping greenhouse gases act like a blanketand keep the surface and the lower atmosphere warmer than it would be without them.

Condition for greenhouse gases in the atmosphere; greenhouse gases include carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), chlorofluorocarbons (CFCs) , ozone (O3) and water vapour (H2O)

The Three Major Greenhouse Gases Produced by Human Activities

These greenhouse gases will reside in the atmosphere for decades or even centuries. The resulting global warming and its effect are thus long lasting.

Ranking Greenhouse Gas Main human emission sources

1 Carbon dioxide (CO2)Fossil fuel use and change in land use

2 Methane (CH4)Agriculture and fossil fuel use

3 Nitrous oxide (N2O) Agriculture

Atmospheric concentrations of key greenhouse gases (carbon dioxide, methane, and nitrous oxide) from 0 to 2005(Source: IPCC, AR4)

CO2 concentration reaches about 386.8 ppm in 2009 !(Source WMO, 2010)

(Source: IPCC, AR4)

It is very unlikely that the 20th century warming can be explained solely by natural causes.

(human-induced)

Natural factors only

Natural + human factors

United Nations and Climate ChangeWorld Meteorological Organization (WMO)

The Intergovernmental Panel on Climate Change (IPCC)

United Nations Environment Programme (UNEP)

United Nations Framework Convention on Climate Change

(UNFCCC) 1994Kyoto Protocol 1997

Copenhagen 2009Cancún, Mexico 2010

First Assessment Report of 1990

Second Assessment Report of 1995

Third Assessment Report of 2001

Fourth Assessment Report of 2007

Fifth Assessment Report (2013-14)

“Warming of the climate system is unequivocal”

“Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (>90% certainty) due to the observed increase in anthropogenic greenhouse gas concentrations”(Source : IPCC AR4)

Key findings from IPCC Fourth Assessment Report (AR4)

Consequences with more greenhouse gases

Greenhouse effect enhanced Rising temperature

Thermal expansion of sea water and melting of snow on land

Sea level rise

Atmospheric circulation changed and the water cycle enhanced

Larger regional differences in

precipitation, and more extreme events

Regional differences in land precipitationThe diagram shows the precipitation trends (1900 – 2005) at various regions. Precipitation curves with white background are having rising trends and those with yellow background falling trends.

(Source: Intergovernmental Panel on Climate Change)

Mean annual mass balance of reference glaciers from 1980 to 2009 with positive values in blue and negative values in red.(Source : World Glacier Monitoring Service, http://www.wgms.ch/mbb/sum09.html)

Changes in glacier mass balance

Melting of ice caps and glaciers

Global warming leads to the melting of ice caps over polar land areas and the glaciers on high mountains. The melted ice-water flows into the sea and contributes to the sea level rise.

Muir Glacier, Alaska's Glacier Bay

August 13, 1941 August 31, 2004

(Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia)

Between 1941 and 2004 the glacier retreated more than twelve kilometers and thinned by more than 800 meters.

Average monthly arctic sea ic

Change in arctic sea ice extent

e extent – summer (September) and winter (January) 1979 – 2010 (Source : U.S. National Snow and Ice Data Center)

Sea level rise

blue：tidal gauge datared：satellite data

Global mean sea level has been rising at 1.8 mm per year in 1961-2003. The rate of sea level rise is higher at 3.1 mm per year in 1993-2003.

(Source: Intergovernmental Panel on Climate Change)

Modeling the future climate

What is going to happen in the 21st Century ?

• “Committed warming” due to GHG already in the atmosphere

• Warming due to future GHG emission

• Warming /cooling due to changes in aerosols concentrations in different regions

• Other natural variability (solar radiation, volcanic activities,El Nino and La Nina, etc.)

+ =

(For illustration purpose only, diagram not to scale)

Global climate projections

Global Climate Models / General Circulation Models (GCMs)

Human factors(Greenhouse gases, aerosols, etc.)

Future climate Intergovernmental Panel on Climate Change (IPCC)Fourth Assessment Report (AR4)

• climate model experiment – 23 models• multi-model data set• 6 greenhouse gas emission scenarios used by IPCC AR4 in global climate simulations • from low to high greenhouse gas emissions are B1, A1T, B2, A1B, A2 and A1FI

Low High

(Source：Intergovernmental Panel on Climate Change, IPCC 2007)

Projected global warming by climate models for different greenhouse gas emission scenarios

Project surface temperature change for the late 21st century (2090-2099)Multi-AOGCM average projection for A1B SRES scenario. Temp relative to 1980-99

Observed Climate Change in Hong Kong

Climate change in HK = Global Warming + Local Urbanization Effect

Element TrendAverage Temperature Increase

Annual Rainfall IncreaseMean Sea Level Increase

Temperature trend in Hong Kong

Annual mean temperature recorded at the Hong Kong Observatory Headquarters (1885-2010). Data are not available from 1940 to 1946

Rainfall trend in Hong Kong

Annual rainfall recorded at the Hong Kong Observatory Headquarters (1885-2010). Data are not available from 1940 to 1946

Number of rain days in Hong Kong (daily rainfall >=1 mm)(at HKO Headquarters, 1885-2010)

All-time record rainfall (hourly) at the Hong Kong Observatory Headquarters (1885 – 2009)

60

70

80

90

100

110

120

130

140

150

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

Year

Hou

rly

rain

fall

rec

ord

(mm

)

1886: 88.4mm

1926: 100.7mm

1966: 108.2mm1992: 109.9mm

2006: 115.1mm

2008: 145.5mm

Time dependent return period analysis of extreme weather events in Hong Kong

Element Return period in 1900 Return period in 2000

Minimum Temperature ≤ 4oC 6 years 163 years

Maximum Temperature ≥ 35oC 32 years 4.5 years

Hourly rainfall ≥ 100mm 37 years 18 years

(Source : Wong, M.C. and H.Y. Mok, 2009: Trends in Hong Kong Climate Parameters Relevant to Engineering Design. HKIE Civil Division Conference 2009 : Conference on Engineers' Responses to Climate Change.)

Annual average of 12-hr 10 minute mean wind speed at King’s Park and Waglan Island (1968-2010)

Annual total number of hours with visibility at HKO Headquartersbelow 8km from 1968-2010

(relative humidity below 95% and not counting rain, mist or fog)

Visibility in Hong Kong

Normal ? Special Weather Phenomena ?

Potential Impacts of Climate Change

Possible Impacts :-

• Fresh Water Resources

• Ecosystems

• Food and forest products

• Coastal systems and low-lying areas

• Industry, settlement and society

• Health

strong winds piling up the sea water near the coast low atmospheric pressure of the tropical cyclone uplifts the sea surface on its path

Storm Surge

Storm Surge + Sea-level Rise

Waves caused by Typhoon

Raised mean sea level

Coast Coast

Original mean sea level

After sea-level rise, storm surges will bring more frequent sea flooding to coastal low-lying areas.

Weather

DirectThermal Stress

IndirectEcologically mediated

Vector-borne diseases

Marine-borne diseases

Food productivity

Weather disasters

- cardiovascular and respiratory morbidity and mortality

- malaria, dengue

- toxic algae, cholera

- malnutrition

- deaths & injuries- damage to health infrastructure- increase risk of infectious diseases- civil disorder/conflicts

An Overview of Weather & Health

0

200

400

600

800

1000

1200

1400

1600

1970 1975 1980 1985 1990 1995 2000 2005 2010Mon

thly

Ele

ctric

ity C

onsu

mpt

ion

per C

apita

(MJ)

Domestic ElectricityCommercial Electricity

Year

1970-2009 Time Series of Seasonal Variation

Variation in electricity consumption in Hong Kong increases significantly in the last 4 decades in both domestic and commercial sectors.

(Source : Climatic Influences on the Energy Consumption in Domestic and Commercial Sectors in Hong Kong, T.C. Lee, M.H. Kok & K.Y. Chan. Presented in the 16th Annual International Sustainable Development Research Conference, Hong Kong, China, 30 May - 1 June 2010, HKO Reprint No. 903)

Climate change : The debate(Source : The Politics of Climate Change By: Anthony Giddens,

http://www.policy-network.net/publications_download.aspx?ID=2596)

Mainstream view –

• Current climate change is real, human influence is very likely one of the main factors influencing the climate in the last decade. Represented by the publications of the IPCC. It aims to gather together as much scientific data as possible, subject it to rigorous review, and reach overall conclusions on the state of scientific opinion, having an enormous influence over world thinking on climate change.

Climate change skeptics -

• Some review and challenge the current understanding via scientific research and discussions, trying to fill in the gaps of the unknowns (Real skepticism).

• Others accept that climate change is happening and that it is humanly induced, but argue that the threat it poses has been exaggerated. Other world problems, such as poverty, AIDS, or nuclear weapons, are both more worrying and pressing than climate change.

• Some claim the case that present-day processes of global warming are produced by human activity is not proven. Fluctuations in climate, they point out, produced by natural causes, have been aconstant feature of world history. (Deniers)

(Source : The Politics of Climate Change By: Anthony Giddens, http://www.policy-network.net/publications_download.aspx?ID=2596

Other views -

• There are several potential “tipping points”.

• Others think we can still hold back the more devastating effects, but to do so we must start taking far-reaching action in the here-and-now.

• Scientist James Lovelock—believe it is already too late to avoid dangerous climate change. We had best concentrate most of our energies preparing to adapt to it and cope as best we can.

(Source : The Politics of Climate Change By: Anthony Giddens, http://www.policy-network.net/publications_download.aspx?ID=2596

Issues that may further complicate the matter !

• Hierarchy and system of the scientific community

• Political and international issues

• Hidden agenda of those with vested interests

• Social and economical culture - mindset change/no change

• Lost in translation - (mass media and Internet)

Challenges

Development &Living standard Environment

No action Act now

Where is the balance ?

Some useful references

Atmosphere and oceanWorld Meteorological Organization (WMO) http://www.wmo.int/pages/index_zh.htmlNASA http://www.giss.nasa.gov/ and http://climate.nasa.gov/National Oceanic and Atmospheric Administration (NOAA) http://www.noaa.gov/climate.htmlChina Meteorological Administration (CMA) http://www.cma.gov.cn/qhbh/National Climate Center (NCC,CMA) http://ncc.cma.gov.cn/cnUK Met Office (UKMO) http://www.metoffice.gov.uk/climatechange/Japan Meteorological Agency (JMA) http://ds.data.jma.go.jp/tcc/tcc/index.htmlAustralian Bureau of Meteorology (BOM) http://www.bom.gov.au/climate/change/

Ice and SnowScientific Committee on Antarctic Research (SCAR) http://www.scar.org/about/National Snow and Ice Data Center (NSIDC) http://nsidc.org/World Glacier Monitoring Service (WGMS) http://www.geo.uzh.ch/wgms/

Sea Level Permanent Service for Mean Sea Level (PSMSL) http://www.psmsl.org/Archiving, Validation and Interpretation of Satellite Oceanographic data http://www.aviso.oceanobs.com/en/home/index.html

Local climate changeHong Kong Observatory (HKO)Climate information services / Climate change webpagehttp://www.weather.gov.hk/cis/climat_e.htmhttp://www.weather.gov.hk/climate_change/climate_change_e.htmEnvironmental Protection Department (EPD)http://www.epd.gov.hk/epd/tc_chi/climate_change/index.html

Useful information when dealing with the climate debate :

Realclimate (more technical approach)http://www.realclimate.org/

Skeptical Science (more layman approach)http://www.skepticalscience.com/

Global Warming: Man or Mythhttp://www2.sunysuffolk.edu/mandias/global_warming/

The book “Merchants of Doubt”http://www.merchantsofdoubt.org/

Thank You