I want to make this one simple as there seem to be lots of people, mainly those with a vested interest, who still refuse to believe (or rather will not allow others to believe) that climate change is happening and it's our fault.

Firstly, definitions. It's called Global Warming because the earth is getting warmer overall - here's a diagram to show this (1):

Lots of denial papers refer to the temperature in the 1990s being cooler than 1944 - well it's warmer now!

We refer to Climate Change a lot because it is sometime difficult to appreciate that the Earth is getting warmer if there are differing effects across the globe. In some places it may be getting cooler, for instance if cool air is being moved with more energy to a warmer place the target will get locally cooler. There are other effects too, in precipitation, wind speed, storm activity and so on. Such is the complexity of the global climatic system that it is extremely unlikely that there will be a consistent temperature from one year to the next in the same place, even if the Global Average Temperature remained static.

So it is getting warmer.

Secondly, Carbon Dioxide (2) and Methane (3) levels are increasing too. These are two greenhouse gases that we do have an impact on (methane is 21 times more effective than CO2). These gases can be the direct result of our activity (burning fossil fuels, cattle effluent), the indirect result of our activity (reduced take up by plankton due to increased ocean acidity, releases from permafrost melting due to increased temperatures) or completely natural (vulcanicity, tectonic movement). The increases correspond accurately with our historic activities. They are, in all likelihood, caused by us.

Thirdly, there is a correlation between carbon dioxide levels and global temperature. A very close correlation (4). Methane increases will actually make the correlation less accurate - unfortunately not for the better.

Fourthly, no matter how much we improve our modelling and increase our computer power, climate change will remain, to a certain extent, unpredictable within the realms of chaos theory. As we improve our models and increase computing power the signs are only becoming more obvious that we are causing a change in the climate which no amount of political lobbying or industrial smokescreening will be able to deny.

Now can we just get on with fixing the problem please.

N.B. Graphs referenced here are from national government or recognised climate science sources  - (1) Hadley Centre for Climate Prediction and Research, (2) US Govt - White House Archives, (3) University of Arizona, (4) Rahmstorf, S., 2004,Climate Change.