Planetary Climate Exercise: Carbon Dioxide Cycle
You are biologists, and your special field of expertise is carbon dioxide (CO2). Carbon dioxide is vital to all plant growth as it is used in photosynthesis, and you have been researching where it comes from and where it goes to.
You have been experimenting with growing exotic fruits near volcanos. All volcanos emit large amounts of carbon dioxide: the more active, the better. In the course of an adventure-filled few years, you have perfected fragrant ‘Popocatapetl Peaches’ from the vast volcanoes of central Mexico, giant ‘Kiwi KucumbersTM’ from the North Island of New Zealand, and the hallucinogenic ‘Fuji Fungi’ from Japan, currently banned in Australia following some unfortunate incidents at raves in Melbourne. But your proudest research triumph has been, without a doubt, the prize-winning ‘Chateau Vesuvius’ 1993 vintage…
In the process of your research, however, you became somewhat perplexed. So much carbon dioxide is being emitted by the world's volcanoes that you would expect that the Earth's atmosphere would be much thicker than it is, and mainly composed on CO2, rather than the nitrogen and oxygen that are its biggest constituents. Where has all the carbon dioxide emitted by all the world's volcanoes since the Earth formed gone?
After exhaustive (and exhausting) research, you have discovered that carbon dioxide is very soluble in water: most of the CO2 produced by volcanoes is dissolved in the sea. You have taken samples of water from all the world's oceans: when you boil the samples, the carbon dioxide is released and can easily be measured. The remainder of the CO2 seems to be in the form of carbonate rocks such as limestone and marble. This is harder to measure, but if you heat the rock samples to 200?c, the rocks release their carbon dioxide and you can measure it. Your next venture involves genetically engineered coconut palms on carbonate rocks buried by lava on a small Caribbean island.

Planetary Climate Exercise: Coal Experts
You are a team of top researchers from the Fossil Fuels Institute, funded by the coal, gas and oil industries. Because of this funding, you have better labs and more accurate equipment than almost anyone else at this conference: you drive nicer cars, live in bigger houses, and can investigate more difficult scientific problems.
You have been doing research on ways to spot bushfires at a very early stage: long before they are dangerous. If you can do this, many of these fires can be put out before they hurt anybody.
Many gas pipelines, coal mines and oil fields are in regions threatened by bushfires: that is why your employers are paying for this research. You hope, however, that your research will be of great use to many other people: it could save a lot of people's lives.
Whenever anything gets hot, it emits infra-red radiation. People are quite hot, for example, and their skin constantly shines with infra-red radiation: this is how people buried in earthquakes are found and rescued. Bushfires are hotter still, so they will emit very intense infra-red radiation.
You plan to use a satellite to scan Australia several times a day with an infra-red camera. All the bright spots will be potential bushfires. Unfortunately, there are a few problems. Infra-red radiation penetrates clouds quite well, so you can see fires all the time. But it doesn't penetrate water vapour very well: if a fire breaks out in a very humid region, all the infra-red radiation is absorbed by the water vapour, and you don't see anything. Infra-red is also blocked by carbon dioxide, so it is hard to spot bushfires near big power-stations, because of all the carbon dioxide they emit when burning coal.
Before you left for this conference, your boss called you in to remind you: you work for the fossil fuel industry, so if you hear of any scientific results that suggest that fossil fuels are dangerous, try and suppress these results. If the conference comes up with a result harmful to your employers, you can kiss your jobs goodbye…

Planetary Climate Exercise: Heat Balance
You work for a top secret government lab, studying space warfare. Indeed, the lab is so secret that when you retire, all memory of it will be wiped from your brain, and replaced with fake memories of a life as turnip farmers.
The big problem in space warfare is not in destroying enemy spacecraft: your colleages in the laser section down the corridor have got plenty of ways of doing that. No: the problem is finding the enemy in the first place, especially if they are in black-painted, radar-absorbing stealthy spacecraft.
The way you figure it, any spacecraft is going be be receiving lots of heat. Firstly, any motors, engines, machines, nuclear reactors, laser guns or cosmonauts on board will generate heat. Secondly, visible light radiation from the Sun will be constantly hitting the spacecraft, and the energy from this solar radiation (which is in the form of visible light) will be absorbed by the object.
If all this heat is being added to an object in space, it will  continuously heat up, unless it can get rid of the heat in some way. On Earth, a cool breeze or a spray of water could cool it down, but in the vacuum of space, there is nothing suitable around. The only option for getting rid of heat energy in space  is to radiate it. Luckily, every object radiates infra-red heat radiation all the time: you are all doing it as you sit there reading this. So is the conference hall, the grass, trees and buildings outside.
So: every object in space will have to radiate infra-red radiation. The hotter it is, the more it will radiate. If it cannot radiate infra-red radiation, for whatever reason, it will just go on getting hotter and hotter, until eventually it is so hot that the infra-red radiation leaks out.
As it happens, you are currently using this knowledge to build infra-red sensitive cameras. This should enable you to spot most enemy spaceships. If they don't try and keep the infra-red radiation in, they will stand out like a sore thumb against the cold darkness of space. If they do try and bottle up their infra-red radiation, by using lots of insulation, the spacecraft will just get hotter and hotter until the cosmonauts inside start frying! But don't tell any of your colleagues too much about this work: you never know who might be a French spy…

Planetary Climate Exercise: Spectroscopy Experts
You are astronomers, unlike most of the others at this rather strange conference. In fact, you are experts at one of the most difficult astronomical problems: measuring the chemical composition of something you cannot even touch. You point your telescopes at distant objects, and by a very detailed study of the wavelengths of the light that you see, you can sometimes determine the chemistry of something far out in space. Strange but true!
You've recently been turning your telescopes on Venus. The data looked quite boring at first: the atmosphere was mostly made of lots and lots of carbon dioxide (CO2), with a few clouds of sulphuric acid droplets to add variety. When you looked more closely, however, some rather surprising evidence came to light. You detected absolutely no water on Venus. However, you do detect some rare isotopes, which are normally found only where water is present.
How come these isotopes are present, but no water? You suspect that the water must have escaped from Venus or been destroyed, leaving behind only these tiny traces of isotopes to show that it was once there. You calculate that, once upon a time, Venus must have had oceans. But where did they go? What went wrong?


Planetary Climate Exercise: Atmospheric Transmission
You all grew up downwind from a tannery, and as a result, you have dedicated your lives to the downfall of companies that pollute the atmosphere. You spend many of your weekends climbing  smokestacks to plant Greenpeace banners on top, or chaining yourselves to factory railings.
On weekdays, you work for a government research institution, trying to invent ways of testing the air over factories to see if companies are breaking anti-pollution laws. The problem is: imagine you suspect that a company is pumping out noxious chemicals. You could get a warrant and go and inspect them, but by the time you do all the paperwork, they might have switched off the offending process. What is needed it a way of seeing what it in their fumes, from outside the factory gates.
You have figured out a brilliant way of doing this. You set up a bright light, emitting lots of visible light radiation and infra-red radiation, on one side of the factory. Then you set up a detector on the other  side, and you see which types of light make it through all the polluted air. 
To make this process work, you need to know which pollutants absorb which types of light. You have spent years shining beams of various  sorts of radiation through test-tubes full of strange gas mixtures. And after years of dogged work, you have concluded that gasses fall into  four distinct categories.
1. Completely Transparent: Many substances, including Nitrogen, Oxygen, Ozone, Xenon, Hydrogen and Helium, are transparent to both visible light radiation and infra-red radiation.
2. Completely Opaque: Some substances, particularly small droplets of water, of sulphuric acid, and of hydrochloric acid, block both visible light and infra-red radiation equally.
3. Visible Light Blockers: Any tiny solid particles, such as diesel fumes, interstellar dust, smoke from burning forests or cities, or tiny dust grains picked up in dust storms, are rather good at blocking visible light radiation, but are poor at blocking infra-red radiation.
4. Infra-red Blockers: A variety of molecular gasses, including water vapor, Methane, and Carbon Dioxide, block infra-red radiation but not visible light radiation.

So far, you have used this technique to prove that a large local manufacturer of hot water systems was using illicit methane-based paints to clean their pipes: infra-red radiation was being severely blocked as it passed over their factory, while visible light radiation was making it through unscathed. You are now working on a visible light based sensor to test that diesel truck engines are correctly tuned up, and not emitting too many tiny solid particles of incompletely burnt fuel. Unless the truck companies persuade the government to shut down your research program…

Planetary Climate Exercise: Water Cycle
You are physicists employed by a company that builds water heaters and showers. You have built up a worldwide reputation for your expertise in the properties of hot water at different temperatures.
At temperatures of around 20?C, water just sits there. Small amounts of water vapor evaporate from the surface, but nothing very significant. Unless you add perfume, that is: perfume evaporates even at 20? C, a feature that led to the success of your ‘smell-good rose-petal washbasinTM’.
If the temperature rises, more and more water vapor evaporates. The increase is dramatic: even small increases in temperature can dramatically increase evaporation rates (think of how much faster your washing dries on the line when the temperature is 20? C rather than 10? C!). You used this fact in your hot-air blowing auto-dry towel-free shower: a best-seller in Japan.
When the temperature rises above 100? C, of course (or slightly higher temperatures if the pressure is higher than that at sea-level on Earth), water will boil, and will all turn into vapor. Water vapor is normally stable: it lasts for ever, as long as the temperature remains high. Unless it is exposed to strong ultra-violet (UV) light, that is. The one blemish on your otherwise brilliant research career was the combined Jacuzzi and sunbed you produced a few years back: as the water vapor steamed off the surface of the water, the UV light from the tanning lamps (designed to mimic the healthy rays from the Sun) broke it down  into hydrogen and oxygen. The oxygen would make people euphoric and sleepy, while the hydrogen built up until any spark (say from the off switch) caused it to explode. Your company is still recovering from all the lawsuits…
