“An analysis of the potential alternative causes of global warming”

Society is persistently told that global warming is anthropogenic, or “man-made”, to which we are told that it is resultant from carbon dioxide emissions. This has often been contested persistently by so-called conspiracy theorists, who claim that it is a natural phenomenon. This forms the basis of my project, for I noted the vast polarization and questioned whether in fact this needs be the case and if some truth may be found on either side.

As part of the preliminary stages to the project I conducted a survey of 90 people on global warming, before I specifically found which area I was going to examine.

Figure 1 – Results of my climate survey

The full set of results can be viewed here, however the results of this survey brought about a single very interesting result. Almost 60% of people believed that there may be other factors that have contributed to global warming besides carbon dioxide, Furthermore, this is strengthened by 25% who were unsure. This was the basis for my project. I found this very interesting, as asking people about other causes in addition to carbon dioxide actually yielded a great amount of support. Other surveys that I have found have asked black and white questions, for example, a 2006 US survey asked “Do you believe global warming can be attributed to: human activity or normal cycles of the Earth’s environment?”  – the results concluded that 53% attributed it to human activity. (, 2006) However, this does not lead by a considerable margin, the remaining 47% evidently show considerable doubt towards it. So are we right to blame carbon dioxide on its own – or do other factors influence it?

The question which arose to me next was what other factors were there? I had already seen the Channel 4 documentary “The Great Global Warming Swindle” which posed numerous factors on how climate isn’t dictated by carbon dioxide. The sceptic view wasn’t one that I was sure I completely backed, but equally I found it hard to picture that carbon dioxide alone was warming the planet. Furthermore, I questioned whether we were warming after experiencing some very cool summers as of late. I decided to contact researchers to help answer these questions and find some focus in my research.

Researchers at Manchester University were exceptionally helpful throughout the course of my research. After a meeting with a researcher, a phone call with another member of the environmental department staff, along with countless emails to other Universities, I managed to establish a general consensus around the researchers. I found that there were the following other prominent areas that were believed to contribute to warming:

  • Milankovitch Cycles
  • Solar Variation
  • Methane
  • Aerosols

All of these factors are discussed on this site with regard to global warming and I hope that I can see whether any evidence exists to link these factors with the warming we see today. The warming we see today is generally not disputed, The 11 warmest years on record have been in the past 16 years, despite my initial reservations on whether or not the warming is true. (, 2007) This is further confirmed by the IPCC (Intergovernmental Panel in Climate Change) the commonly sighted “hockey stick” graph shows how temperatures have deviated from recent cycles, as pictured in figure 2.

Figure 2 – Temperature Change (IPCC Report, 2001)

The following pages will attempt to account for some this warming from other reasons than carbon dioxide emissions.

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