22 September 2007

Beautiful science explains climate

By Andrew Boswell

The greatest science can be understood by its simple relationship to the world. When something can be seen, heard or experienced through other senses, then we trust it.

As children develop spatial awareness, they start to understand how 'things' work. It's a wonderful experience to watch children as they explore the world, and a great moment for parents when share that Eureka moment as their child first sees a ball bounce, or an apple falling from a tree. A child learns to trust that a ball thrown in the air will return to earth, and in a predictable way.

Humanity had been on earth for thousands of millennia before Isaac Newton coined the term 'gravity'. Gravity, of course, had always existed. Newton just gave this name to the attraction between objects. Well not just - Newton, of course, did a great deal more, and developed an entire world view – Newtonian mechanics - that remained the pre-eminent understanding of the universe for two hundred years and is still by applied scientists including engineers and astronomers.

Newton largely developed his world view from 'first principles' and through the realms of mathematical logic. This is another essential of brilliant science - understanding a phenomenon from a simple logic, or deriving it from first principles. This also gives trust as we can feel that the process relates to something very fundamental.

The falling apple was described by Newton's in beautifully, simply formulas lead to an understanding of the motion of planets and our physical world. To look at Newton’s work is to see true beauty.

So too, with Einstein's theory of special relativity The beauty of Einstein's early work around 1905 was that it was derived from first principles. So simple, an A-level maths pupil can understand the equations and their logic. Just by working in this first principles way, Einstein was able to derive the famous formula E=mc2.

Those with great vested interest, like large oil companies and even the US government, don't care about science or truth of climate change and have put out that climate science is not to be trusted. Yet climate science is grounded too in first principles science, but this is largely ignored in the media.

Malicious climate deniers largely concentrate on trying to cast aspersion on climate computer models. This is because people can't see a climate model, nor understand its inner workings, so it is easy to build a false 'trust' problem. However many times Al Gore or leading scientists show how the models accurately predict current temperature rises in terms of both greenhouse gas emissions and background cycles some people just won't 'get it'.

Now, these computer models are essential tools in predicting and understanding the details of global warming. However, they are not actually the fundamental science. Let me briefly explain that science.

The Greenhouse Gas effect that underlies global warming is based on an effect called 'radiative forcing'. This is a measure of how much heat radiation leaving the earth is absorbed in the upper atmosphere – by greenhouse gases such as carbon dioxide – and is reflected back.

Radiative forcing is like gravity, it has always existed. There has always been a background level of carbon dioxide and other gases in the atmosphere, and some heat from the earth has always been reflected back by them. Without this greenhouse effect we would be a cold planet like Mars. The effect was first recognised over one hundred years ago.

The first principles of radiative forcing are that gases are made of molecules and molecules absorb heat radiation. Every chemistry student knows this causes molecules to vibrate with greater energy. However, such excited molecules don't hold this extra energy for long and they re-emit it. Radiative forcing happens because the heat is coming from the earth in one direction – out towards space – but the heat re-emitted is in all directions – in other words, half of it travels back towards the earth. Simply, the more gas, the more radiative forcing.

There is no reason why anyone who accepts that gravity exists would not also accept that radiative forcing exists. Climate sceptics may deny computer models, but why do they deny fundamental properties of matter that have been accepted for hundreds of years?

Recently Channel 4 broadcast another program where Michael Meacher and a top Met Office scientist were confronted with an audience clearly chosen because the majority of them were climate sceptics. This was such a lost opportunity to have a real discussion about the real first principles science that sceptics are failing to grasp.