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The Greenhouse Effect
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29 Articles
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Richard Lindzen on Climate Sensitivity

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Dr. Richard Lindzen wrote this special report on climate sensitivity for the CO2 Coalition. It is commonly accepted that increasing CO2 in the atmosphere should lead to some warming, but the amount depends on how the initial warming by CO2 will affect water vapour and clouds. Simple descriptions of the greenhouse effect (GHE) consider clear skies without clouds, but the infrared opacity of upper-level cirrus clouds is often large enough that when such clouds are above the emission level for the greenhouse gases, they block the infrared radiation from from the gases, and the new emission level is near the top of these clouds. Climate models fail to describe the behavior of upper-level cirrus clouds. The areal coverage of such clouds decreases with temperature, acting as a negative feedback. The observations of top of the atmosphere radiative fluxes show that there are no long-wave positive feedbacks and that they may well be negative. This means that CS above 1.5 °C are very unlikely and that it is likely around only 1 °C, which would be beneficial to the global economy.



How Much CO2 and the Sun Contribute to Global Warming

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A simplified climate model and extensive line-by-line radiation transfer calculations are used to investigate the contribution of greenhouse gases, mostly CO2, and solar effects to global warming over the 20th century. The simulations reproduce the direct, no-feedback equilibrium climate sensitivity (ECS) of CO2 as estimated by the IPCC within a few percent. The model gives a positive water vapour feedback of not more that 14%, which is 1/7 of the IPCC's value. The model shows that the surface temperatures increase faster than air temperatures, so warming causes more convection and evaporation and precipitation, resulting in strong negative feedbacks. The simulations show that the global warming and cloud changes can best be explained when the temperature feedback on clouds has only a minor effect but the sun induced lower cloud cover. The author estimates the climate sensitivity of 0.7 °C and a solar sensitivity of 0.17 °C for a 0.1% increase in TSI. The sun contributed 60% and GHG contributed 40% of the warming over 100 years.



Climate Models Have Been Predicting Too Much Warming

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Dr. John Christy argues that the surface energy balance is like a tug-of-war with cooling factors against the sum of three warming factors; downward atmospheric radiation, solar radiation, and our extra greenhouse gases (GHG), mostly carbon dioxide. Our emissions of GHG are about 0.34% of the total warming factors. Christy removed the effects of ENSO and volcanoes from the 38-years of satellite temperature data and found the remaining temperature trend is 0.095 °C/decade. The average troposphere temperature rise would be 1.1 °C at the time when CO2 levels double. The corresponding value of the climate models' average is 2.3 °C, so the models over-warm the atmosphere by more than a factor of 2. The models project a warming in the tropics between altitudes 9 - 12 km of 0.44 °C/decade, but the observation (weather balloons etc.) show only about 1/3 of that. The models are wrong be a factor of three! This paper is based a talk given by Dr. John Christy at the Palace of Westminster, U.K. on 8 May 2019.



Total Precipitable Water and the Greenhouse Effect

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Total precipitable water is an important climate parameter as it is a measure of the total amount of water vapour which is the most important greenhouse gas in the atmosphere. Water vapor increases with global warming and in the climate models it amplifies the direct small warming caused by anthropogenic greenhouse gas emissions. It is often incorrectly assumed that an increase in total precipitable water corresponds to a positive water vapour feedback. The greenhouse effect is very sensitive to water vapour in the upper atmosphere. This article shows that based on humidity data from a major reanalysis dataset, declining humidity in the upper atmosphere offsets the greenhouse effect of increasing humidity in the lower atmosphere. The greenhouse effect of increasing water vapour in the atmosphere may not have caused a positive water vapor feedback, contrary to climate models. This may explain why the climate models have simulated a global surface warming from 1979 to 2018 of over twice the satellite observed warming.



Do Atmosphere Temperatures Support Greenhouse Gas Warming Theory?

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This paper evaluated the atmospheric temperature trends of the UAH satellite temperature record to determine if the data supports the theory that global warming is mainly due to the increase in greenhouse gases (GHG). Four metrics of the GHG theory were compared to the data. Each of the four metrics is contrary to GHG theory. The atmospheric temperature data does not support the GHG theory, but contradicts it. The paper also investigated the temperature variability of the troposphere and the lower stratosphere and to determine whether these are associated. It shows the intrinsic properties of the thermal regime in the lower stratosphere are not associated with the thermal regime in the troposphere.



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