Humans, Cycles, Sun or Ice-ages - What affects our climate most?
One of the most important questions facing mankind in the twenty-first century is to what degree is human activity responsible for climate change, particularly temperature change, and is there anything that we can or should do about that?
This issue can be focussed on narrowly or broadly and entirely different answers arrived at. Some of the relevant aspects are the long term ice-age or Milankovitch cycles, medium term solar fluctuations, the effect of human's burning fossil fuels, the possible bias in sampling locations, and ecological and political propaganda.
On a scale of thousands of years, we are due for a steep drop in temperature as we enter another ice age. This could start next week or not for a thousand years, we do not know.
On a scale of hundreds of years, we are at or possible past a peak of a 500-600 year cycle. This cycle appears to be associated with the rise and fall of major civilisations.
On a scale of decades, present temperatures have risen very sharply and are due at least partly to solar activity. Solar cycles have become very strong and continue to defy predictions and get still stronger. Temperatures on earth are correlated with the strength of sunspot cycles although we have only a relatively short record of this. Howver we do know that stronger sunspot cycles also tend to be shorter and we do have a longer record of sunspot cycle period length.
There can be no doubt that human activity has added immensely to the amount of CO2 in the atmosphere. However models on this have not been able to predict how much CO2 is absorbed by the oceans. The uncertainties are added to by measurements being taken in cities where temperature change may be only a local effect and apparent sea level changes may be caused by sinking.
For these reasons great care needs to be taken in formulating government and international policy is regard to things that affect our climate. Further care needs to be taken because there can be no doubt that politics and interest groups are now involved in these discussions and wish to influence the perception of results for reasons not related to the public good.
Cycles Research Institute wishes to assist in providing reliable data from all time scales relating to climate change.
Climate Cycles and Fluctuations - Resources and Data
World Data Center for Paleoclimatology - Climate Reconstructions. Has reconstructions on many scales and from many sources. The two graphs on this page come from this NOAA Paleoclimatology site.