Long-term data sets for global temperature indicate a clear and consistent increase in global temperatures, particularly since the industrial revolution in western countries.

Large variations, resulting from events such as volcanic eruptions, can make the short term trend in global temperature change difficult to establish, but the long term data sets available allow the bigger picture to be seen.

Much of the argument surrounding climate change hinges not on whether global warming is occurring, but rather whether this warming is a result of human activity. Natural causes, such as sun-spot activity, have been invoked by some to explain the accelerated rate of global warming in recent decades.

In recent years though, even those previously sceptical of human-induced global warming have largely recognised the important role our greenhouse gas emissions are playing in climate change.

Figures courtesy of the Intergovernmental Panel on Climate Change (IPCC). Click figures to enlarge.

As concentrations of the main greenhouse gases have risen in our atmosphere, global temperatures have increased at a similar rate. See the Human Influence page for data sets on carbon dioxide, methane and nitrous oxide.

As this site is devoted to greenhouse gases I will not here extensively cover the subject of global warming. There are several excellent websites, see the links page, where the various data and arguments can be seen and assessed.

My only recommendation is that readers look at several sites before they form a final opinion on the importance and causes of global warming. For myself, it is one of the greatest threats humankind is likely to face in the 21st century.