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7 Articles

Cloud Studies Suggest Low Climate Sensitivity as Aerosols have Smaller Effect than Previously Thought

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Two new experiments at CERN using the CLOUD chamber (Cosmics Leaving OUtdoor Droplets) near Geneva, Switzerland show that the pre-industrial earth was cloudier than previously assumed. Most climate scientists assumed the skies were sunnier before the use of coal and other fossil fuels because sulfur dioxide released by burning the fuels oxidizes to sulfuric acid which creates aerosol particles that seed cloud formation. One experiment shows that organic vapours emitted by trees produce abundant aerosol particle in the atmosphere in the absence of sulfuric acid.It was previously thought that sulfuric acid is the key player in cloud formation. Since clouds reflect sunlight back into space, any extra clouds could have offset a portion of greenhouse gas warming. A second CLOUD experiment showed that the small aerosol particle could rapidly grow to sizes big enough to seed cloud droplets. Another group of researcher measured the concentrations of sulfuric acid and organic molecules in the Swiss Alps. They observed that aerosols formed from organic molecules without sulfuric acid. The new results show that modelers can’t offset as much CO2 forcing with aerosol cooling so climate sensitivity to CO2 emissions is lower than modelers assumed and future temperature increase will be much less than currently projected by climate models.



El Nino Warming Reduces Climate Sensitivity

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Global average ocean temperature variations to 2,000 m depth during 1955 - 2011 are simulated with a 40 layer 1D forcing-feedback-mixing model. The model included ENSO-related changes in cloud cover preceding the temperature change. The time lag and amount of cloud changes were adjusted to make the best match to the ocean temperature and the CERES satellite observations. When the cloud effects of ENSO are included, the equilibrium climate sensitivity falls from 2.2 to 1.3 Celsius for double CO2, or a 41% reduction. The ENSO process causes clouds to change, causing a temperature change. Part of the 20th century warming was caused by ENSO activity.



Satellite Measures a Drop in Cloud Height

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Stereo measurements from a NASA satellite show the global cloud height has dropped about 1% from 2000 to 2010, allowing them to radiate more heat to space which cools the planet. The drop in average cloud height is largely due to fewer high clouds. Low clouds radiate more energy to space than high clouds.



Feedback in the Presence of Unknown Radiative Forcing

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This paper by Dr. Roy Spencer examines radiative feedbacks and presents a way to separate the feedback signals from radiative forcing signals in satellite data. It shows that the radiative forcings from cloud changes give the illusion of a positive cloud feedback. The true feedback signal found in the satellite data shows a strong negative cloud feedback to temperature changes of 6 W/m2, equating to a climate sensitivity of 0.6 Celsius. This makes CO2 emissions a non-issue.



Clouds Have Made Fools of Climate Modelers

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A detailed analysis of cloud behavior from satellite data by Dr. Roy Spencer of the University of Alabama in Huntsville shows that clouds provide a strong negative feedback, the opposite of that assumed by the climate modelers. The modelers confused cause and effect, thereby getting the feedback in the wrong direction.




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