Jan 052016
  • Changes in the Rate of Sea Level Rise; Gavin vs Eschenbach

    Gavin Schmidt says that sea level rise has accelerated since 1860, but Willis Eschenbach says "Yes, a quadratic provides a better fit than no acceleration, but NOT significantly better. Which means you can't claim acceleration. Eschenbach analyzed the statistical significance the the variance between the quadratic and linear fits of the Church and White 2011 data. Church and White are experts is creating reconstructions of global sea levels from tide gauges. Eschenbach shows that there were large changes in the 31-year trends over the 20th century, ranging from a low of 0.80 mm/y ending 1931 to a high of 2.10 mm/yr in 1961. He concludes "The 95% CI for each of the residuals encompasses the variance of the other residual … and this means that there is no statistical difference between the two. It may just be a random fluctuation, or it might be a real phenomenon. We cannot say at this point." […]

  • Uncertainties in Greenhouse Gas Induced Climate Change

    Friends of Science advisor Madhav L. Khandekar wrote a report describing the uncertainties in greenhouse gas induced climate change and problems with climate models, dated March 2000. Since then the discrepancies between the climate model's hindcasts and the climate measurements have only grown larger. The mean surface temperature increase during 1978 to 1997 was 0.32°C, however, the impact of urbanization and land-use changes may have contributed about 0.1°C to that increase. The temperature trend in the lower atmosphere 1979-1998 was about 0.10°C/decade which is much less that the 0.16°C/decade at the surface, contrary to theory. The cause of the temperature change is a combination of natural variability including solar effect and anthropogenic sources. There are large uncertainties in radiative forcings by aerosols, which may offset a significant part of the greenhouse gas forcing, and in cloud and sea ice cover. […]

  • The Impact of Recent Forcing and Ocean Heat Uptake Data on Estimates of Climate Sensitivity

    Climatologists Nicholas Lewis and Judith Curry published an important paper in the Journal of Climate that estimates the climate sensitivity to CO2 using the energy balance method. Using the temperature history (HadCRUT4.5), ocean heat data and the most recent climate forcing information, the authors estimate the equilibrium climate sensitivity is 1.50 deg C, which is only 47% of the climate model average value. The likely uncertainty range is half of that estimated by the IPCC. The paper also refutes criticism of the energy balance method. While the paper does not address possible natural temperature recovery from the Little Ice Age, it concludes that the high values of climate sensitivity from climate models are inconsistent with the observed warming. […]

  • Tracing Winter Temperatures Over the Last Two Millennia

    This paper presents a winter temperature reconstruction using fjord sediments from Sweden. The temperature was determined by using a temperature sensitive isotope in small, shallow water animals. The temperatures range from 2.7 to 7.8°C. The record shows high temperatures during the Roman Warm Period, variable during the Dark Ages, high temperatures during Medieval Warm Period, cooling with multi-decadal variability during the Little Ice Age, and warming during the 20th century. The late 20th century warming “does not stand out in the 2500-year perspective and is of the same magnitude as the Roman Warm Period and the Medieval Climate Anomaly.&rdquo […]

  • Correcting Flaws in Global Warming Projections

    Ron Clutz wrote a summary of a paper published posthumously of Dr. Bill Gray’s understanding of global warming/climate change. The global climate models (GCM) all project than an increase in CO2 warming leads to an increase in atmospheric water vapour. This results in the water vapour, which is a strong greenhouse gas, to cause further warming. In contrast to this positive feedback built into GCMs, Dr. Gray believes that there is a negative feedback, meaning that the temperature rise would be less than the direct effect of the theoretical CO2 warming. The paper says “CO2 warming ultimately results in less water vapour (not more) in the upper troposphere. The GCMs therefore predict unrealistic warming of global temperature. He hypothesize that the Earth’s energy balance is regulated by precipitation (primarily via deep cumulonimbus convection) and that this precipitation counteracts warming due to CO2.&rdquo […]

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