A friend writes that I am a “climate-change denier”, and during a presentation, another friend angrily accused me of denying climate change. I call them “natural climate-change deniers”.
I often speak and write about five periods of natural climate change with warming greater than the present in the past 10,000 years since the end of the Ice Age. Thousands of science studies bear witness that “the only constant in climate is change”. Al Gore of “An Inconvenient Truth”, and Michael Mann of the “Hockey Stick”, both deny proven climate science: five periods in the recent past had natural warming much greater than now. The warmest was the Holocene Climate Optimum, 8,000-5,000 years ago, followed by the Egyptian, Minoan, Roman, and Medieval Warm Periods, each of which was cooler than its predecessor. Current warming is by far the least warm of the six, and seems exceptional only in light of historical climate science ignorance and the fact that it followed the longest and coldest period of the past 8,000 years, the Little Ice Age (1350-1850AD).
Climate records of the past 900,000 years show long glacial periods (ice ages) surrounding shorter interglacial (warm) periods. The previous interglacial was the Eemian, 125,000 years ago, with sea levels 20 feet higher and temperature 5°F warmer. Nature did then what Al Gore says humans are doing now. However, a Global and Planetary Change paper finds that changes in CO2 follow rather than lead global air surface temperature and that "CO2 released from use of fossil fuels have little influence on the observed changes in the amount of atmospheric CO2.”
Among many errors, my computer-literate friend missed that Anthony Watts won both the 2011 and 2012 Best Science, and 2012 Lifetime Achievement, on the Bloggies.
Natural climate-change deniers prefer their beliefs to the facts I present.