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26 Articles

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

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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.

Climate Sensitivity from the Bulk Troposphere

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A new study by John Christy and Richard McNider used the warming of the bulk troposphere from satellite data to calculate an upper limit on transient climate sensitivity. The study removed ocean effect like El Nino and effect to two major volcanoes to determine a temperature trend attributable to only greenhouse gasses and natural forcing. If natural forcing contributed nothing, which is extremely unlikely, the temperature trend is 0.069 °C, giving a climate response of 1.1 °C, which is about one-half of the value estimate by climate models. A link to the paper is at the end of the article.

Estimating Climate Sensitivity Using Two-zone Energy Balance Models

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Empirical estimates of equilibrium climate sensitivity (ECS) can be obtained by comparing measurements of short-term radiation changes at the top of the atmosphere during the satellite era to corresponding changes in surface temperatures. Dr. Ray Bates from University College Dublin estimates ECS using a two zone energy balance model, where the radiative responses in the tropics (30 N to 30 S) and extratropics are estimated separately, and the dynamic heat transport from the tropics to the extratropics are explicitly estimated. Using likely ranges of the parameters from observations, he finds that the ECS is tightly constrained with a best estimate of 1.02 °C and a likely range of 0.85 °C to 1.28 °C.

CLOUD Experiment Reduces Climate Sensitivity to CO2

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The CLOUD experiments at the nuclear facility CERN showed that the ionization of the atmosphere by cosmic rays account for nearly one-third of all particles formed. The experiments also shows the aerosol particle formed from biogenic nucleation from naturally produce organic vapour “was the dominant source of particles in the pristine pre-industrial atmosphere”, and that the amount of aerosol was much higher than previously assumed. That means that pre-industrial atmosphere was cloudier than previously assumed, as the aerosols seed cloud formation, and that greenhouse gases caused a much smaller portion of the warming since pre-industrial times. The climate sensitivity in climate models must be reduced for them to match past aerosol amounts and the temperature record.

15 Years of CERES Versus Surface Temperature: Climate Sensitivity = 1.3 deg. C

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Dr. Roy Spencer analysis 15 years of CERES satellite net top-of-atmosphere radiative measurements verses HadCRUT4.3 surface temperature, utilizing annual data with a four month time lag to maximize the correlations. Spencer writes, "Time-varying radiative forcing in the climate system (e.g. due to increasing CO2, volcanic eruptions, and natural cloud variations) corrupt the determination of radiative feedback. ... diagnosing feedback by comparing observed radiative flux variations to observed surface temperature variations is error-prone…and usually in the direction of high climate sensitivity." Using annual data reduces the noise caused by El Nino and La Nina. The results of the analysis shows a climate sensitivity of 1.3 deg. C. This analysis still includes non-forcing radiative noise, so the actual climate sensitivity is likely less than 1.3 deg. C for double CO2.

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