Australian Institute of Physics (Vic Branch) Education Committee The Science of Climate Change:...

PowerPoint PresentationThe Science of Climate Change:
Explaining why we need to act NOW
Prepared with material from NPL (UK), IPCC, BOM (Aus)
Welcome to this talk on the Science of Climate Change. My name is X and I teach at Y. This talk is an initiative of the Education Committee of the Victorian Branch of the Australian Institute of Physics who are feel that Climate Change is a concern requiring urgent action. This is why we are concerned
Australian Institute of Physics (Vic Branch) Education Committee
Why the urgency?
variation in the last few million years
SOURCE: "Summary for Policymakers"—A Report of Working Group I of the Intergovernmental Panel on Climate Change, 2001
The panel merges proxy data (year-by-year blue line with very likely ranges as grey band, 50-year-average purple line) and the direct temperature measurements (red line) for the Northern Hemisphere. The proxy data consist of tree rings, corals, ice cores, and historical records that have been calibrated against thermometer data. Insufficient data are available to assess such changes in the Southern Hemisphere.
2nd slide from NPL
The Science of Climate Change:
The Earth’s atmosphere
Radiation and Greenhouse Effect
How has the climate already changed?
What do the models predict? Cause for concern
Expressing concern
This is the structure of my talk. First, the Earth’s atmosphere
1. The Earth’s Atmosphere
4.5 billion years ago rock fragments orbiting the sun formed a rocky planet.
Volcanoes produced the first atmosphere, nearly all water vapour and some gases including sulfur dioxide (SO2), carbon dioxide (CO2) and ammonia (NH3).
The water condensed to form the oceans.
Early aquatic life produced oxygen.
Oxygen enabled more complex life forms to evolve about 500 million years ago.
The gases in the atmosphere took some time to reach their current proportions.
In the last 500 million years the composition of the atmosphere has been largely unchanged, but the climate has swung between ‘Hothouse Earth’ and ‘Snowball Earth.
It is important to appreciate that the Earth has had, and could have again, very different climates. The details are not precise, but the general picture is well established.
The interaction of these factors is not clearly understood
Causes of Climate Changes
Changes in greenhouse gases
Volcanoes
Bubbles in Antarctic Ice
Carbon Dioxide in the atmosphere
Current value
389 ppm
variation in the last few million years
Pre-1950 data is from analysis of gas bubbles in ice cores from the polar regions
Post 1950 data from Muana Loa
Expressing concern
Electromagnetic Radiation
This radiation comes in many forms.
It is radiation from the Sun that is our ultimate energy source, it underpins life on the planet.
They differ from each other in the same way as the signals from radio stations differ.
They differ only in the frequency, and because they are all waves, also in their wavelength.
Electromagnetic radiation from a hot body
How does an object get hot when placed in front of a fire?
Electromagnetic radiation from a hot body
This radiation is called Blackbody radiation,
because it has nothing to do with the inherent colour of the object.
Hot objects give out much more radiation than warm objects,
Hotter objects give out shorter wavelengths.
*
Radiation
and with
but the Earth is much cooler and dimmer.
What determines the Earth’s surface temperature?
Light from the Sun heats the Earth…
The Earth then radiates the heat away…
Light from the Sun
When there is balance, the Earth’s average temperature will be stable
heat input from the Sun
heat lost from the Earth by radiation
When there is a balance between:then the Earth’s average temperature will be stable
Earth
Above the Equator
Earth
Whole Earth Average 340 W/m2
that the 680 is the day/night average, as is the 340 (which is just ¼ of 1360)
Light from the Sun
Light from the Sun
Average Value
Average Value
240 watts
How hot must the Earth be to radiate 240 W/m2 ?
-18 °C
Average Value
Actual average
surface temperature
The Stevenson Screen is made of wood, hurrah,hurrah!
The Stevenson Screen is made of wood, hurrah,hurrah!
The Stevenson Screen is made of wood, If it was made of tin it would be no good.
Run, run, run, run, for to get out of the rain.
The Stevenson Screen is painted white, hurrah, hurrah!
The Stevenson Screen is painted white, hurrah, hurrah!
The Stevenson Screen is painted white, It looks like a ghost in the middle of the night.
Run,run,run, run, for to get out of the rain.
The Stevenson Screen has slatted sides, hurrah, hurrah!
The Stevenson Screen has slatted sides, hurrah, hurrah!
The Stevenson Screen has slatted sides, The air passes through but it isn't too wide.
The Stevenson Screen has a double lid, hurrah, hurrah!
The Stevenson Screen has a double lid, hurrah, hurrah!
The Stevenson Screen has a double lid, If you were inside you would think that was guid.
The Stevenson Screen is a metre high, hurrah, hurrah!
The Stevenson Screen is a metre high, hurrah, hurrah!
The Stevenson Screen is a metre high, Not big enough to touch the sky.
The Stevenson Screen is on short grass, hurrah, hurrah!
The Stevenson Screen is on short grass, hurrah, hurrah!
The Stevenson Screen is on short grass, What rhymes with grass? Well I think I'll pass.
The Earth’s surface is 33 °C warmer
than it would be if it had no atmosphere
So how does the atmosphere
warm the Earth’s surface?
Gases in the Atmosphere
Gases in the Atmosphere - Now
Concentration in 19th century
Nitrogen (N2), Oxygen (O2) & Argon (Ar)
More than 99% of the atmosphere
These molecules have one or two atoms
They block some ultra-violet light, but
Allow infra-red and visible radiation through.
1000 Watts per square metre at the Equator:
At - 18°C there would be no water and probably no life (although internal heat sources in the Earth might provide a reservoir for life)
Actually Oxygen (O2) does have a little absorbtion, but lets ignore that.
With an atmosphere of Nitrogen Oxygen & Argon, what would be the surface temperature?
-18 °C
Average Value
Average Value
240 watts
Greenhouse warming is caused by
Water (H2O)
What is special about H2O and CO2?
Their molecules have three atoms,
Their natural frequencies of vibration are in the infra-red,
They are the earth’s blanket for reflecting certain infra-red frequencies back down to earth.
1000 Watts per square metre at the Equator:
At - 18°C there would be no water and probably no life (although internal heat sources in the Earth might provide a reservoir for life)
What is special about H2O and CO2?
Their molecules vibrate or jiggle in a variety of ways.
So, many infrared frequencies can make them move.
All these frequencies are absorbed.
Infrared Bands absorbed by Water and CO2
Infra Red
Ultra Violet
Out of balance…
In balance at + 15 °C…
On Average:
240 W/m2
On Average:
390 W/m2
150 W/m2
Greenhouse Warming
33 °C
Amount of CO2 in the air over time
With increasing CO2, more radiation is reflected back to earth, raising its temperature.
1.4 ppm per year
In this data from Muana Loa observatory one can see the seasonal variations due to plant growth
Expressing concern
Climate models are:
Science-based tools for studying how climate varies and how it is changing.
They use mathematical representations of physical laws, including Newton's laws of motion, conservation of mass and energy, heat flow, and gas laws.
They represent important processes in the atmosphere, ocean, land surface and ice, as well as how these interact with each other.
There are more than twenty different models developed independently around the world.
Climate models: Specific factors
Energy balance: Incoming solar radiation, Planetary movements, Cloud reflection, Aerosol/dust reflection, Surface reflection and absorption.
Water Cycle: Evaporation, Cloud formation, Precipitation, Interception by leaves and branches, Runoff
Flow of air and water: Air Pressure, Circulation of air up and around – winds, Circulation of water down and around – currents, Effect of a rotating earth
IPCC AR4 WGI FAQ1.2 Fig 1
Climate Models
The air and the oceans are broken up into cells.
http://www.bom.gov.au/info/climate/change/gallery/54.shtml
Climate Models
The equations are applied to the cells of air and water to see how much air and heat energy flows between each pair of cells.
This is repeated all around the Earth.
The models have improved by making the cells smaller.
They are now about 110 km square by 1 km high.
IPCC AR4 (First assessment report, Second, Third, 4th)
Observations:
1980-99
What do models show?
Black: Temperature measurements
Red: Predictions by models assuming human factors such as CO2 emissions as well as natural ones such as sun cycles and volcanic eruptions.
WGI Fig TS.23
WGI Fig TS.23
Blue: Predictions by models assuming only natural factors.
‘Most of the observed increase in global average temperatures since the mid-20th century is very likely (more than 90% certain) due to the observed increase in anthropogenic greenhouse gas concentrations.’ IPCC(2007)
Observed Temperature changes
*
The black line represents no warming. Where is the black line and what does that mean? No warming from when?
http://www.cru.uea.ac.uk/cru/climon/data/themi/g17.htm
Expressing concern
Germany
Other
observations
Argentina
Climate change impacts
Greenland ice sheet
The Greenland summer ice melt is getting larger at a worrying rate.
From GEO 4 report
Human induced changes
The Arctic Ice is melting at a much faster rate than predicted
http://www.ucar.edu/news/releases/2007/seaice.shtml
Impact on the oceans
CO2 is absorbed by the oceans, making them more acidic.
This weakens marine skeletons.
A change of 0.1 in pH is a 26% change in the acidity of the water.
10 million 1 million
years ago years ago
Expressing concern
Annual warming for 2080-2099
Watterson and Arblaster (2005)
A1: storyline and scenario family: a future world of very rapid economic growth, global population that peaks in mid-century at 9 billion and declines thereafter, and rapid introduction of new and more efficient technologies. A convergent world - income and way of life converge between regions with extensive social and cultural interactions worldwide
A1B - A balanced emphasis on all energy sources
Average of the change in temperature* by 2070 predicted by 15-models.
*relative to 1990.
Emission scenarios
Figure 10.4. Multi-model means of surface warming (relative to 1980–1999) for the scenarios A2, A1B and B1, shown as continuations of the 20th-century simulation. Values beyond 2100 are for the stabilisation scenarios (see Section 10.7). Linear trends from the corresponding control runs have been removed from these time series. Lines show the multi-model means, shading denotes the ±1 standard deviation range of individual model annual means. Discontinuities between different periods have no physical meaning and are caused by the fact that the number of models that have run a given scenario is different for each period and scenario, as indicated by the coloured numbers given for each period and scenario at the bottom of the panel. For the same reason, uncertainty across scenarios should not be interpreted from this figure (see Section 10.5.4.6 for uncertainty estimates).
Emission scenarios
A1B A Balanced emphasis on all energy sources.
A1T Emphasis on
non-fossil energy sources.
Figure 10.4. Multi-model means of surface warming (relative to 1980–1999) for the scenarios A2, A1B and B1, shown as continuations of the 20th-century simulation. Values beyond 2100 are for the stabilisation scenarios (see Section 10.7). Linear trends from the corresponding control runs have been removed from these time series. Lines show the multi-model means, shading denotes the ±1 standard deviation range of individual model annual means. Discontinuities between different periods have no physical meaning and are caused by the fact that the number of models that have run a given scenario is different for each period and scenario, as indicated by the coloured numbers given for each period and scenario at the bottom of the panel. For the same reason, uncertainty across scenarios should not be interpreted from this figure (see Section 10.5.4.6 for uncertainty estimates).
Scientists say that ‘2 degrees of warming is locked in’, but that is only the most likely outcome, …
Tipping points
On avoiding dangerous anthropogenic interference with the climate system: Formidable challenges ahead
http://www.pnas.org/content/105/38/14245.full
Chart1
0
1.1578947368
1.2631578947
1.3157894737
1.5789473684
1.8421052632
2.1052631579
2.3684210526
2.6315789474
2.8947368421
3.1578947368
3.4210526316
3.6842105263
3.9473684211
4.2105263158
4.4736842105
4.7368421053
5
5.2631578947
5.5263157895
5.7894736842
6.0526315789
6.3157894737
6.5789473684
6.8421052632
7.1052631579
7.3684210526
7.6315789474
Probability
Committed warming as of 2005 due to GHGs (degrees C)
Probability
0
0
0.0066
0.009
0.087
0.294
0.444
0.48
0.444
0.381
0.315
0.249
0.198
0.153
0.12
0.099
0.0804
0.0606
0.051
0.0408
0.036
0.0288
0.0252
0.0228
0.021
0.0174
0.0156
0.0138
Sheet1
3.8
2
Temperature
Probability
Probability
0
0
0
0
2.2
1.1578947368
0
0
2.4
1.2631578947
1.1
0.0066
2.5
1.3157894737
1.5
0.009
3
1.5789473684
14.5
0.087
3.5
1.8421052632
49
0.294
4
2.1052631579
74
0.444
4.5
2.3684210526
80
0.48
5
2.6315789474
74
0.444
5.5
2.8947368421
63.5
0.381
6
3.1578947368
52.5
0.315
6.5
3.4210526316
41.5
0.249
7
3.6842105263
33
0.198
7.5
3.9473684211
25.5
0.153
8
4.2105263158
20
0.12
8.5
4.4736842105
16.5
0.099
9
4.7368421053
13.4
0.0804
9.5
5
10.1
0.0606
10
5.2631578947
8.5
0.051
10.5
5.5263157895
6.8
0.0408
11
5.7894736842
6
0.036
11.5
6.0526315789
4.8
0.0288
12
6.3157894737
4.2
0.0252
12.5
6.5789473684
3.8
0.0228
13
6.8421052632
3.5
0.021
13.5
7.1052631579
2.9
0.0174
14
7.3684210526
2.6
0.0156
14.5
7.6315789474
2.3
0.0138
2.8
1.4736842105
Sheet1
Probability
Probability
Sheet2
Sheet3
What the models show: Early and late 21st C
WGI Fig SPM.6
Potentially vulnerable systems in Australia
Projected climate change hotspots in Australia (from IPCC AR4 WGII, chapt 11)
“ This is not just an environmental problem. It is a defence problem. It is a problem for those who deal with economics and development, conflict prevention, agriculture, finance, housing, transport … trade and health”.
UK Foreign Secretary, Margaret Beckett, The Age, Oct. 26, 2006
“ It is a matter of social justice. If we care about injustice and inequality, we must care about climate change. Climate change exacerbates existing inequalities.”
Barbara Stocking — Chief Executive, Oxfam GB, Oxford, England
Expressing concern
Expressing concern
Political: Write and phone and fax and email and talk to your local members (State and Federal, upper and lower house, Council).
Advocate one or more of the following:
A maximum global CO2 level by 2020 (2050), e.g. 350 parts per million.
Zero emissions by Australia by, for example, 2050
Carbon emissions tax with a tax rebate for low income earners
Subsidy of alternative fuels: including Geothermal, Solar Thermal, Wind, PV, Nuclear and Biomass from a carbon emissions tax .
Feed in tariffs for solar panels.
Expressing concern
Retrofit double glazing,
Put up pelmets,
Install compact fluorescents,
Use public transport,
Use throw rugs,
“The Hot Topic: How to tackle Global Warming and still keep the lights on” by Gabrielle Walker and Sir David King.
Politicians
PO Box 6022, House of Representatives, Parliament House,
Canberra ACT 2600. Tel: (02) 6277 4230, Fax: (02) 6277 8428
North Ballarat Office: 5 Lydiard Street, North Ballarat Vic 3350
Tel: (03) 5338 8123, Fax: (03) 5333 7710.
State Member for Melton District: Donato Nardelli (ALP)
3 Alexandra St, Melton 3337 Tel: 9743 9825, Fax: 9743 1634
State member for Western Victoria region: Jaala Pulford (ALP)
15 Main Road, Ballarat 3350 Tel: 5332 2405, Fax: 5333 3109
Probability
0
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0
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CO
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Australian Institute of Physics (Vic Branch) Education Committee The Science of Climate Change:...

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