Climate Science

The Science of Climate Change is Fairly Straightforward

It Is Forecasting the Impacts of Climate Change That is More Complicated

There are two types of 'scientific facts’ and the science of climate change contains them both.

The first type of scientific fact is of the variety that our planet spins around on its axis at a speed of over 1,000 mph (at the Equator) while the whole planet hurtles round the Sun at about 67,000 mph. The reason we don’t fall off is due to an invisible force called gravity. These are fundamentally true facts that were true before we humans ‘discovered’ them and will continue being fundamentally true regardless of what else happens in our lives.

The second kind is the type that covers statements like, ‘If you step in front of a car travelling at 40 mph and it doesn’t stop, you will most likely die from the experience.’ This type of fact does involve a degree of uncertainty as some people will manage to survive the impact but they really are few and far between: about 1 out of every 20 who make the attempt. The reason is it more difficult to be certain about the outcome is the complexity of the systems and forces that are involved in a collision between a pedestrian and a vehicle. The shape of the vehicle and whether there are protruding bit of metal, the physical condition of the pedestrian to begin with, the nature of the surface that the pedestrian lands on following the collision. These all have an impact and can influence the outcome. Most of us, though, accept that the outcome is certain enough to avoid stepping out in front of vehicles.

When it comes to the science of climate change, the ‘fundamentally true’ element is that certain kinds of gasses, when present in a planets atmosphere, cause that planet to retain heat more than it would if those gasses were not present. The amount of heat retained is related to the concentration of those gases, namely carbon dioxide (CO₂), methane (CH₄) and Nitrous Oxide (N₂O) hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF₆). Water vapour will also affect temperature. The effect of these gasses can be observed in laboratory experiments and the warming effect of each can be calculated. Collectively these six gases are referred to as greenhouse gases (GHGs).

These gasses are increasing (see below) in their concentrations and the global average temperature is increasing.




Since the 1950's, the level of CO₂ in the atmosphere has been measured at the Mauna Loa Observatory and provides a monthly reading.



Carbon dioxide (CO₂) is the most common of the gases and the warming effect of the other gases is often expressed in an amount equivalent to that of CO₂. This can sometimes be confusing as it leads to several figures being used to describe how much GHG there is in the atmosphere . The following chart shows how the various figures join up.


The pre-industrial level of around 280 ppm is pretty much the long term average, at least when considered in the terms of human history and it is this level that is associated with what we know for sure to be a safe climate for humans. The complex part of the science is trying to work out how much the temperature will increase given a range of possible combinations of concentration of the various gases and how this will impact upon the weather systems that we currently rely on. It may seem strange to think that we rely on the weather but unless we have a climate that is reasonably stable, we lose the ability to grow food, for example.

Trying to resolve this complexity is the main task of the Intergovernmental Panel on Climate Change (IPCC) a collection of scientists who review the work of other scientists. This was established in 1988 (yes, that is 22 years ago) and has, to date, made 4 reports (in 1990, 95, 2001 and 07). Each report has become more and more certain that the climate is changing due to human activities and that given current trends, temperature extremes, heat waves, and heavy precipitation events will continue to escalate in frequency; and the earth’s temperature and seas will continue to rise into the next millennium.

If you would like to look more deeply into the evidence, a good place to start is the ‘Summary for Policymakers’. However, the earliest effects are being seen in the Arctic, as shown in the graphics below.

Satellie image of summer ice coverage 1979 and 2007



Of couse, the problem with looking at just two data points is always the choice of which two to look at. Unfortunately, it doesn't get any better when you look over time, as the following chart shows.




Actually doing something about the level of GHG’s in the atmosphere has been a particularly difficult political and social problem. This is primarily because modern civilisation is dependent upon energy and fossil fuel is currently the fuel of choice. Oil, in particular, is used for much more than just its energy potential and has a major impact on our food chain and on medicines. ‘Giving up’ fossil fuel is neither easy nor popular but it is entirely possible. There is sufficient energy from the Sun hitting the planet in one hour to power all human activities for a year. However the economic and accounting system that we currently use means that the incentives to develop methods of extracting it (i.e. that people can make money from it) will not develop through market forces for many years. The fear of the climate scientists is that by that time, it will be too late.

There are a few isolated scientists who claim that climate change is not a problem at all, that global warming does not exist. They are given a surprising amount of media coverage but that is probably because they use words like "scam" and "con" to describe the orthodox science. The media finds that controversy gets more attention than collaboration. The argument these scientists, and their supporters, put forward is well presented and draws upon lots of data that categorically shows that global warming isn't happening. They argue robustly when questioned on a public stage although to witness such an exchange brings to mind the old saw of "lies, dammed lies and statistics". Rather than accept that "toxic sludge is good for you" a US professor John Abraham took the trouble of looking at the presentation of Lord Christopher Monckton, one of the leading mouth pieces of the contra-camp and found that they regularly misinterpreted and misrepresented the work of others that they quote and that much of the data presented has no quoted provenance at all. If you would like to see & hear the detailed examination of Monckton's work you can see it here.

There is also an excellent series of videos on YouTube that illustrates the background and history of the whole issue in an easy to understand way.