Continued from yesterday…
One of the most contentious scientific subjects today is climate change. The basic premise is this: that by burning fossil fuels we are releasing gases into the atmosphere, principally carbon dioxide, that act to trap heat close to the planet and will warm it up. In fact the “greenhouse effect” has been working on our planet since its creation, it’s some basic thermodynamics I did in my first year at university that if the Earth re-radiated energy as efficiently as it absorbs it, it would have an average surface temperature of about minus twenty degrees Centigrade.
Well, we know the thermal properties of carbon dioxide, it does indeed act like this. That’s one reason why the Earth is as warm as it is.
We know the size of the atmosphere, and we know how much carbon dioxide it contained before the advent of the industrial revolution. We know how much coal and oil and gas have been extracted and burned since then, and how much they should have released into the atmosphere. We know how much carbon dioxide is in the atmosphere now, and the numbers do add up. We have weather stations around the world, and they tell us that temperatures are rising. We have models of the Earth’s climate on super-computers that we use to make weather forecasts, and they predict the long-term changes we are seeing if we plug in the numbers.
Of course there are objections…
- How do we know the results of all the weather stations are good? There is an effect called the “urban heat island” where cities are hotter than their surrounding terrain, especially at night, and many weather stations are situated in cities. That would skew the results and make it look as if the world is warming up. Answer: There are actually two results of the urban heat island – one is that weather stations in cities will record higher temperatures; the other is that weather stations just outside cities actually show cooler temperatures than normal. They do this because the hot air over the city rises, drawing in cooler air for around it. That breeze cools the weather stations just outside the city. Scientists initially compensated for these effects by excluding both sets of data from the figures. More recently satellites launched by NASA and ESA have made direct measurements that confirm the predictions of climate change.
- The biggest greenhouse gas by heat trapped is not actually carbon dioxide, it is water vapor, good old H2O. Humans have not been emitting H2O, but the less important CO2, so how can we say it is cause by humans? Answer: Two thirds of the planet’s surface is covered by water, and the amount of water held in the atmosphere is a function of the temperature of the atmosphere. So if the carbon dioxide we release warms the atmosphere just a little, it will hold more water vapor, which will help warm up the planet a little more, which means the atmosphere holds a little more water vapor…It’s what we call a positive feedback cycle, and the carbon dioxide is still the key.
- How do we know that it’s not the Sun warming up that is causing the changes in the climate? Answer: Because we have space craft like SOHO measuring the Sun’s energy directly. The Sun’s output does vary very slightly on an eleven year cycle, but that’s all. No other changes have been found.
- Climate changes naturally, how do we know this is not part of the Earth’s normal changes? Answer: we have a pretty good idea of what causes the changes in the Earth’s climate, and what few are ongoing at the moment, like the Milankovich Cycles that cause the Ice Ages, indicate that we should be going into a cooling period, instead things are warming up. The only anomalous factor is that carbon dioxide…
- Even if climate is changing, it changes naturally, so what’s so bad? Answer: we have built our entire civilization in a particularly stable period of climate that made agriculture possible, we have no guarantees that the future climate will be able to sustain sufficient agriculture to feed seven billion people. What is more, sea levels are going to rise as the heat melts ice currently on land over Greenland and Antarctica. Last time there were four hundred parts per million of carbon dioxide in the atmosphere, sea levels were at least twenty-three feet higher than now; that would inundate many coastal cities. Climate changes have been associated with mass extinctions, when large numbers of entire species die out. That’s not a good thing.
- But we had a really cold winter last year! Answer: Other people had a really mild winter, dry winter, or wet winter. Global climate is global, some places will be warmer and some colder. It all averages out. As the heat balance of the atmosphere changes so will the weather in many places. It’s a very complex system that is still very hard for us to predict accurately on a local level.
- If it’s so complex, how can you say the world will warm up? Answer: Because it’s complex on a short-term local level, not on a long-term global level. We don’t fully understand the intricacies, but we know enough for the science to be solid that we are changing the climate.
- It’s all a conspiracy; these scientists are releasing alarmist reports to get big grants! Answer: the first half of this article explains why that isn’t so. In thirty years of climate research, no-one has broken ranks and written the paper that debunks the rest and claimed their Nobel prize. That’s what would be happening if climate science is all a fraud, given how science operates. The biggest prize is to the guy that breaks ranks, not the guy that supports the conspiracy. Even groups of scientists funded by climate skeptics, like the Berkeley Group, concluded that the science of climate change was good, there was no conspiracy, no cover up, the world really was warming as a result of fossil fuel burning (and got their funding cut, go figure).
So what is the controversy?
Well as far as the science is concerned, there is none. The world IS warming, and the greenhouse gases our civilization has produced are the largest contributing factor to this change. But there is a problem with this: people do not want to believe it. The debate has become politicized and legalized, and thrown into the media, because the debate could NOT be won in the lab through scientific debate. The reason it couldn’t be done is simple: it’s true. But as we saw with vaccines, it’s not enough to be right – the media has to be willing to believe you are right, and that’s a whole different ball game.
Once you plant seeds of doubt, they will always grow in some minds. However, what is good is that questioning is all part of the scientific process, so we need to question, constantly. The only problem is when questioning constantly paralyses us from taking action.
As they say in Gloucestershire, “Red sky at night…barn’s on fire!”