APDL Eductation Resources/APDL Eductation Resources.iso/programs/misc/co2effect/!CO2effect/!Help

Text File | 1994-06-08 | 23.4 KB | 492 lines

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!CO2effect           Version 1.0a (DEMO ONLY version)           30th May 1994
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                         (c) 1994 Bandy Ridgwell



                              Introduction
                              ============


!CO2effect is a Global Warming simulation, which will model future
'greenhouse' gas (namely CO2, CH4, N2O, CFC-11, CFC-12 and HCFC-22)
concentrations and mean global surface temerpature, from given current and
future rates of 'greenhouse' gas emissions.  Policy senarios for controlling
or reducing the emissions of the various greenhouse gases from their major
sources can be built up, and the simulation run to give the future
atmospheric composition, and to predict the future mean surface temperature
(globally and yearly averaged).  Historical data back to 1750 is included so
that future levels and trends can be compared with the past, and
particularly with before the start of the Industrial Revolution.


The main features include:

     * Prediction of mean global surface temperatures from three (currently)
       different simple models, scaled to fit the prediction of current GCMs
       (Global Circulation Models), or from a user-defined model.
     * Calculation of the future concentrations of the main "greenhouse"
       gases.
     * Historical data for gas concentration back to before the start of the
       Industrial Revolution (back to 1750).
     * Rates of emissions from all primary anthropogenic sources are
       individually fully adjustable.
     * 4 policy 'senarios' pre-loaded; including the latest IPCC
       (InterGovernmental Panel on Climate Change) "Buisness As Usual"
       (no additional action taken to reduce emissions) prediction for
       future emissions.
     * Total rates of emissions can be set independantly of their individual
       sources.
     * All graphs fully scalable; main graph may be drag-magnified.
     * Main simulation and emissions graphs can all be saved as draw files.
     * Emission parameters can be saved from and loaded into the application.
     * Emission parameters can be saved as a text file.
     * Acorn's Interactive help supported.


***** This demo version has had the rates of emissions feature cripled, *****
**** such that changes made to the various emissions sources will not be ****
*************** made permanent and used by the simulation. ******************
****** Additionally, no user-defineable model functunality is present. ******


**** This program is designed to ideally run under RISC OS 3.1, and looks ***
***** best a high resolution screen mode.  However the program will run *****
*** adequately in a low res mode, and under RISC OS 2 the only difference ***
******* will be that the rotated text y-axis labels will be missing. ********



                            About the simulation
                            ====================


  Put very simply, the Earth's climate system works as follows:

  The Earth absorbs radiation from the Sun, mainly at the surface.  This
energy is then redistributed by the atmosphere and ocean and re-radiated to
space at longer ('infrared') wavelengths.  Some of the thermal radiation is
absorbed by radiatively-active ('greenhouse') gases in the atmosphere,
principally water vapoir, but also carbon dioxide, methane, nitrous oxide,
the CFCs, ozone and other greenhouse gases.  The absorbed energy is re-
radiated in all directions, downwards as well as upwards such that the
radiation that is eventially lost to space is from higher, colder levels in
the atmosphere.  The result is that the surface loses less heat to space
than it would otherwise do in the absence of the greenhouse gases and
consequently stays warmer than it would otherwise be.  This phenomenon,
which acts rather like a 'blanket' around the Earth, is known as the
greenhouse effect.  Without such a blanket, the average surface temperature
would be well in excess of -10°C (the global everage surface temperature is
about 15°C).
  All of the greenhouse gases except the man-made CFCs are natrually present
in the atmosphere, so that global warming is about the 'enhancement' of the
'natural' greenhouse effect by the addition of greenhouse gases from
anthropogenic sources (since the start of the Industrial Revolution).

  The greenhouse gases modelled in this simulation are (with currect (1990)
contribution to the enhanced greenhouse effect (ie global warming));

  CO2                 -  61.2%
  CH4                 -  17.1%
  N2O                 -   4.1%
  CFC-11  (CCl3F)     -   2.5%
  CFC-12  (CCl2F2)    -   5.7%
  HCFC-22 (CHClF2)    -   3.5%

  The remaining 5.9% is due to changes in stratospheric water vapour comming
about as an indirect effect of changes in methane concentration.  This is
not modeled in this version.

  The gas referred to as HCFC-22 in the simulation, is used as a surrogate
for all halocarbon CFC-11 and CFC-12 substitutes.



  The simulation consists of two main parts; the calculation of the levels
of emissions of the greenhouse gases from their various sources; and the
calculation of the gas concentration levels these emissions will lead to,
and thus the resulting mean surface temperature.



                            1. Emissions modelling
                            ======================


  The primary anthropogenic sources of the various greenhouse gases are as
follows, (sources in parenthesies are not adjustable in this version):

Gas     Real source       % importance      v1.0a model source
                       (by mass emissions)

CO2  -  energy                       80%    energy use, transport
        deforestation                17%    deforestation, reforestation
        cement production            03%    misc sources - cement production

CH4  -  energy production and use    26%    energy use, transport
        enteric fermentation         24%    agriculture - livestock
        (rice)                       17%    (remaining sources)
        animal wastes                 7%    agriculture - livestock
        landfills                    11%    misc sources - sewage & landfills
        biomass burning               8%    deforestation
        domestic sewage               7%    misc sources - sewage & landfills

N2O  -  energy                        9%    energy use, transport
        fertilized soils             48%    agriculture - fertilizers
        (land clearing)              17%    (remaining sources)
        adipic acid production       11%    misc sources - acid production
        nitric acid production        4%    misc sources - acid production
        biomass burning              11%    deforestation

CFCs -  the individual sources are not modelled.  Overall production is
adjustable, and all this production is assumed to find it's way into the
atmosphere the same year.

[The above figures are taken from the latest IPCC assessment]


  Future emissions may be adjusted in two differect ways; either by
setting each source of the various greenhouse gases individually (some of
the sources are common to more than one greenhouse gas, e.g. deforestation
is responsible for the release of CO2, CH4 and N2O) in the various source
windows; or by setting the total levels (by growth/reduction of from 1990
levels) of each greenhouse gas using the 'Set Emissions' window (e.g. the
emissions of all greenhouse gases could be held at 1990 levels using this
window).  Thses windows are accessed from the emissions toolbar by
clicking SELECT.  Future changes in the various emisions sources or
emissions levels are set in up to 5 phases (phase #0 is not adjustable
(except in the 'Set Emisions' window).  Values are 'phased in' over the time
scale set (ie intermediate value are interpolated), except for percentage
change values (e.g. growth in the number of vehicle miles travelled (VMT) in
the transport window) which are kept constant at the set value for the
duration of the phase.  Phases can be set from 1 to 155 years (inclusive).
Each source window works as follows;

  - Electricity Generation:  Electricity is generated from a combination of
5 sources (coal, gas, oil, nuclear or renewables (including solar, wind,
hydo, biomass and geothermal).  Each source will produce a different
quantity of greenhouse gases for each KWh of electricity produced; the ratio
of these emissions are taken to be 57:24:42:9:1.  These take into account
all emissions arrising as a consequence of construnction, getting the fuel,
operation and decomissionsing.
  For the four fundimentally thermal processes, the power stations can be
forced to be of a Combined Heat and Power variety, where an equal amout of
energy to the electricity generated, is assumed to be made available as heat
(e.g. hot water).  No allowances are made for future increase in generation
efficiency.  The graph will display either the percentage share of
generation, or the make-up of the actual power (electrical) generated,
depending on the status of the 'Absolute/Percentage Display' icon.

  - Energy Use Per Year (Excluding Transport):  The amout of electrical
energy generated and the total energy consumed per year may be set.  The
percentage of the remaining energy requirements met by renewables (biomass
or solar-derived hydrogen fuel) as opposed to fossil fuels may also be set.
Renewables are assumed to count for no emissions.

  - Transport:  The rate of growth of the number of Vehicle Miles Travelled
(the total number of miles travelled by all road vehicles) per year can be
set.  Cars account for about 72% of the total number of VMT.  'Vehicle
efficiency' is taken to be the percentage of potential fuel energy which is
made available for vehicle motion.  'Level of bio-fuels used' is the
percentage of vehicle fuel that comes from non-fossil fuel (e.g. sugar cane
derived ethanol, oil fractions from oil seed rape and potentially solar
hydrogen in the future) sources, currently this is 45% for Brazil.  'Level
or car sharing' is the average percentage passenger car load (ie 50% would
be two people in a nominally 4-seater car).  The graph will display either
the number of VMT as a percentage of the VMT for 1990, or as an absolute
value, depending on the status of the 'Absolute/Percentage Display' icon.

  - Halocarbon/Substitute Production/Use:  The percentage balance of the
different halocarbons and non-halocarbon substitutes used for current
halocarbon uses can be set.  These must add up to 100%.  The total
production (taken also to the the total emissions for that year) can also be
set (in kilo-tons).

  - Deforestation/Reforestation:  The area of forest cleared per year can be
set.  This forest is taken to be entirely tropical/sub-tropical (temperate
deforestation is relatively insignificant).  Emissions (CO2, CH4, N2O)
associated with each hectare of cleared forestation are released that year.
Reforestation takes carbon out of the atmosphere ('fixes'); this is assumed
to take place over 25 years (amount absorbed declining linearly per year);
the total quantity absorbed from the atmosphere being equal to half that
released from an equivalent area of deforestation (which will almost always
be a mature forest, with a much higher biomass per hectare).  Reforestation
can counter the effects of deforestation and lead to a net absorption of
carbon from the atmosphere (the emissions for carbon will then be negative).

  - Agriculture:  Livestock is defined here as cattle, horses, mules/asses,
buffalo, camels, sheep, goats and pigs.  'Synthetic fertilizer use' is the
total mass of artificial nitrogen-containing fertilizer (largely nitrate and
ammonium fertilizer) produced and used each year.  Typically around 3% of
the nitrogen finds it's way into the atmosphere in the form of N2O.

  - Misc Sources:  These three sources are as percentages relative to 1990
emission levels.  Adipic acid production is largely for use in the making of
Nylon 66.  Nitric acid is used in the production of fertilizers.

  Once the parameters in the window have been set, click 'OK' (or 'Update'
if the window has it) to make the application accept the new values,
(otherwise any changed values will be lost when the window is closed).  The
main simulation and emssions windows will now be stared (*) to indicate that
the emissions sources have been altered.  The 'Update Emissions' icon now
needs to be selected so that emissions for the years 1990-2150 can be
calculated for each of the greenhouse gases.  The main simulation and
emssions windows will then be un-stared.


  The 'Set Emission Levels' window allows the total emissions of the 6
greenhouse gases to be set, independantly of their individual sources.  The
gases to have thier total emisisons set should be selected.  Phase number #0
can in this window be set.  Selecting either 'Set' or 'OK' will automaticall
update the total emissions, so that it is unnecessary to click on the
'Update Emissions' icon.


  Complete sets of emissions source details can be saved as a parameter
file, and subsequently loaded into the application again by dragging the
file icon into any of the application's windows.  Details of total emissions
levels set using the 'Set Emissions' window are not saved.  Built into the
application are 4 ready setup future emissions source senarios which can be
loaded up by clicking SELECT or ADJUST over their icons (the 4 numbered
smoking chimneys), (the 'Update Emissions' icon will need to be clicked on
to update the actual emissions).  These senarios have been set up as follows;

  #1  Largely the IPCC prediction of future greenhouse gas emissions if no
additional action is taken to limit them.  The balance of electricity
generation sources is my guess.
  #2  Made up - medium-high emissions.
  #3  Made up - medium-low emissions.
  #4  The energy consumption data, and balance of generation sources is from
a World Bank assessment of a renewable-intensive and low consumption
senario. CFCs and their current replacement (HCFCs) and phased out very
rapidly, and replaced with non-halocarbon compounds.  The rest is just made
up for an extreme greenhouse gas avoidance policy.


  By clicking on any of the various greenhouse gas 'Emissions Windows'
icons, a window will be opened for that greenhouse gas, displaying the level
of emissions for that gas from 1990 onwards.  They will each be opened in
the same place, so that opening a second window will hide the first (so drag
it somewhere else!).  The window may be toggled between displaying a
percentage scale relative to 1990 emissions levels, and an absolute scale by
clicking on the 'Absolute/Percentage Display' icon.  The y-axis scale may be
set from the 'Percentage Of 1990 Levels' window (even whe the graph display
is in absolute units, the scale is set here as a maximum and minimum
percentage of 1990 levels).  The time period displayed may be set from the
'Time Axis Display' window (any period strating from 1990 to any ate in the
range 1995-2150).  Clicking on the 'Close Emissions Windows' icon will cose
any emissions windows currently open.
  Clicking with ADJUST on any of the following icons;
  Energy Use, Transport, Deforestation/Reforestation, Agriculture, Misc
Sources or Remaining Sources will switch the emissions window to displaying
theri respective greenhouse gas emissions solely from that set of sources
(ie clicking ADJUST on the Deforestation/Reforestation will switch the CO2
emisions window to displaying carbon emissions solely from deforestation and
reforestation processes).  By clicking either SELECT or ADJUST on the 'Total
Gas Emisisons' icon, or by clicking with ADJUST on an icon already selected
by ADJUST, will switch the emissions window back to displaying total
emissions (ie from all sources combined) again.  x or y-axis grids can be
displayed by clicking on and selecting the relevant grid icon (and made to
disappear by clicking on and deselecting them again).



    2. Modelling of atmospheric composition and mean surface temperature
    ====================================================================


  As the main simulation is run;

  Each year a quantity of the various greenhouse gases (depending on how the
emissions have been previously set) are added to the atmosphere.
  The quantities added are assumed to decay depending on the atmospheric
half-lives of the gases (with a simple exponential in the cases of CH4, N2O,
CFC-11, CFC-12 and HCFC-22, but with a more complicated  decay in the case
of CO2).  The quantities remaining from that single years' emssions are
calculated for each of the subsequent years up until the end time of the
simulation, and added to the amount already in the atmosphere in each of
those years.
  The radiative forcing for each of the greenhouse gases due to the quantity
of that gas in the atmosphere over and above that for years prior to the
Industrial Revolution is calculated.  Radiative forcing is a measure of the
increase in the trapping of outgoing terrestrial (infrared) radiation from
the Earth's surface, due to a increase in the concentration of a greenhouse
gas in the atmosphere.  It is measured in Watts per square meter, and is
equivalent to an additional (infrared) radiation source acting (downwards)
on the tropospere.
  The mean surface temperature is then calculated by whatever model has been
selected.  Three simple ones have been provided (future versions of the
application may have much more complicated ones); all are of the same form,
and each has been simply scaled to fit the results of a GCM (Global
Circulation Model), either a low, high or 'best' estimate.  The effect of
the heat capacity of the Earth's oceans has not been taken into account
(which will act to smear out and delay global temperature changes).


  The running of the simulation is controlled by the group of icons in the
top LH corner of the main simulation window; running from left to right all
the icons are:

  PLAY - Starts the simulation running.

  PAUSE - Pauses (/continues) the simulation.

  STOP - Stops the simulation, (once it has been stopped it cannot be
  restarted without resetting).

  BLANK - Blanks (/unblanks) the plot,  (useful if the plot is floodfilled,
  as this takes quite some time to redraw if windows are moved from infrount
  of it).

  RESET - Resets the simulation; this may be done at any time.

  SPEED - Makes the simulation run normal speed (fast!) or slowely (one year
  every ten seconds).

 (EMPTY)

  TIME AXIS DIAPLY PARAMETERS - Opens window.  Sets the time period to be
  displayed (any period between 1750 and 2150 inclusive), and whether the
  time axis grid is on or off.  The max time values the simulation is
  started with, is the time the simulation will calculate up until.

  LH Y-AXIS DISPLAY PARAMETERS - Opens window.  Sets the max and min values
  on the LH y-axis, and whether the LH y-axis grid is on or off.  Sets the
  colour of the plot, and also the plot size.

  RH Y-AXIS DISPLAY PARAMETERS - Opens window.  Sets the max and min values
  on the RH y-axis, and whether the RH y-axis grid is on or off.  Sets the
  colour of the plot, and also the plot size.

  CONFIGURATION PARAMETERS - Opens window.  Parameters for the configuration
  of the plot display.  The various options are as follows:
  Plot fill: The plots may be either flood filled (solid colour under each
  plot) if selected, or not.
  Plot shape: The plots may be displayed as a point, a cross or as a
  continuous line.  The point and cross size are determined by the 'Plot
  Size' parameter in the LH and RH y axis display paramater windows.
  y-axis scale: The plots may be display as absolute values, or as excess
  values (Global Warming is usually talked about in terms of excess values
  over pre-Industrial Revolution (say 1750) values, or excess values over
  1990 values.
  LH y-axis display: The LH y-axis may be set to display either temperature
  or radiative forcing.
  RH y-axis display: The RH y-axis may be set to display either CO2, CH4 N2O
  or CFCs.  Additionally the CFCs may be displayed seperately ('All gases?'
  selected) or combined (ie total CFCs).

  ALL/SINGLE - The display may be toggled quickly between displaying all
  gases floodfilled, or just one (CO2) not foodfilled.

  COLOURS - Opens window.  The display colours for the 6 different gases and
  combined CFCs may be set.  When the plot is displayed floodfilled, cross
  or line displays (in addition to the floodfill) are displayed in black.

 (EMPTY)

  EMISSIONS TOOLBAR - Opens the Emissions Toolbar (described above).
  Clicking with SELECT will close the main simulation window.  Clicking with
  ADJUST will leave it open.

  TEMPERATURE MODEL - Opens window.  For selecting which temperature model
  to use.  In this version the user-definable one is not selectable.

 (EMPTY)

  QUICK SAVE - Saves the main simulation graph using the last saved draw
  file path and filename.

  HELP - Loads up Acorn's Interactive Help (RISC OS versions 3.00/3.10/3.11).


  Selected areas of the main graph may be magnified by dragging out a box
encompasing that area (move the mouse with SELECT or ADJUST held down).  No
further magnification is allowed by this means when a certain limit has been
reached.  Additionally, very small dragged boxes are ignored.

  If the main simulation window or one of the emissions windows have the
input focus, then that graph may be saved by pressing F3 (providing that a
save path has previously been provided, or a draw file has previously been
saved).





                            Further Information
                            ===================


Climate Change; The IPCC Scientific Assessment. CUP 1990. ISBN 0 521 40360 X
Global Warming; The Greenpeace Report. OUP 1990. ISBN 0 192 86119 0


A wide variety of information on Climate Change, including material suitable
for schools use can be obtained from:

  Global Climate Change Information Programme
  Atmospheric Research and Information Centre,
  Department of Environmental and Geographical Sciences,
  Manchester Metropolitan University,
  Chester Street,
  Manchester
  M1 5GD

  Tel: [phone]
  Fax: [phone]





                              Copyright Notice
                              ================


!CO2effect is (c) 1994 Bandy Ridgwell, all rights reserved.

This software is supplied "as is"; no warranty, express or implied of its
fitness for any particular purpose is given.  In no circumstances shall the
author be liable for any damage, loss of profits, or any indirect or
consequential loss arising out of the use of this software.





******************** To obtain the full working version *********************

      Send a cheque for £10-00 made payable to "Andy Ridgwell" to:

      390 Milton Road,
      Cambridge
      CB4 1SU


  For this you will recieve the latest full working version of !CO2effect,
together with full (uncrunched and commented) versions of the source code
and a printed manual (of sorts) detailing how exactly to use the program, a
more detailed explanation of the greenhouse effect and how it is modeled,
the assumptions behind the simulation model and how everything is calculated.
  I will also notify you of any updates (which will cost only enough to cover
postage and packing and the disk).

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The author can be contacted at;

390 Milton Road,
Cambridge
CB4 1SU


The author may be plied with drinks at;

The Ancient Druids,
Cambridge


Bandy Ridgwell  30/05/94