Tuesday, November 2, 2010

Review of Holocene 'Climate Optimum' shows Temperatures 2°C hotter than Present

A new peer-reviewed paper Climate change between the mid and late Holocene in northern high latitudes reviews 110 temperature proxies of the past 6000 years in the northern high latitudes and finds "A large majority of the here investigated temperature reconstructions indicate that temperatures were warmer at the mid-Holocene [6000 years ago] compared to the preindustrial period [500 years ago], both in summer,winter and the annual mean. By taking simple arithmetic averages over the available data, the reconstructions indicate that the northern high latitudes were 1.0°C warmer in summer, 1.7°C in winter and 2.0°C warmer in the annual mean temperature at the mid-Holocene (6000 years ago) compared to the recent pre-industrial." The paper also notes (p. 6) that the temperature change via proxy reconstructions from years 1501 to 2000 "appears to be only ~0.05°C for the Northern Hemisphere as a whole according to data from Mann et al (2009)." [that is not a typo - the paper states five one-hundredths of one degree change from pre-industrial 1501 AD to the year 2000]
Therefore, annual northern hemisphere temperatures during the Holocene 'Climate Optimum' 6000 years ago were ~1.95°C hotter than at the end of the 20th century. The "hockey team" of Michael Mann et al has claimed that prior warming periods were localized to the European Arctic, but this extensive review shows the current warming is not unprecedented, not localized, and was greatly exceeded in the recent geologic past. 

Note: the Corrigendum of this paper contains the updated figures above.


  1. what's your point? so it was hotter before the industrial revolution, big deal. It's since the industrial revolution we have to be concerned about!

  2. The points are
    1. Contrary to claims of the IPCC, the planet has naturally been much hotter than the present multiple times even within the past 8000 years, and there is no evidence that the current warming cycle is unprecedented or any different or caused by CO2.
    2. Temperatures much higher in the past did not cause a "tipping point" that alarmists claim is already happening.

  3. All that is happening now is that the Sun's energy output has been increasing since about 1880, allowing the Earth to thaw from the Little Ice Age. This is well within the realm of normal temperature variations.

    If one looks back a few thousand years, one finds the Earth is somewhat colder now. Let's hope this warm period does not end soon. The next Ice Age will not be pleasant.

  4. Poor sun, never gets the recognition it deserves, because it is out of reach of socialist control.