Radiation Transfer Calculations and Assessment of Global Warming by CO2

Hermann Harde

doi:10.1155/2017/9251034

Abstract

We present detailed line-by-line radiation transfer calculations, which were performed under different atmospheric conditions for the most important greenhouse gases water vapor, carbon dioxide, methane, and ozone. Particularly cloud effects, surface temperature variations, and humidity changes as well as molecular lineshape effects are investigated to examine their specific influence on some basic climatologic parameters like the radiative forcing, the long wave absorptivity, and back-radiation as a function of an increasing CO2 concentration in the atmosphere. These calculations are used to assess the CO2 global warming by means of an advanced two-layer climate model and to disclose some larger discrepancies in calculating the climate sensitivity. Including solar and cloud effects as well as all relevant feedback processes our simulations give an equilibrium climate sensitivity of CS = 0.7°C (temperature increase at doubled CO2) and a solar sensitivity of SS = 0.17°C (at 0.1% increase of the total solar irradiance). Then CO2 contributes 40% and the Sun 60% to global warming over the last century.

Highlights

We present detailed line-by-line radiation transfer calculations, which were performed under different atmospheric conditions for the most important greenhouse gases water vapor, carbon dioxide, methane, and ozone
The Fifth Assessment Report (AR5) [1] of the Intergovernmental Panel on Climate Change (IPCC), a list of all abbreviations is found in the annex, announces new evidence of an anthropogenic climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes, and simulations using climate models
A quite critical report of published ECS values and accounting methods expanded in AR5 has been published by Lewis and Crok [17]. In this contribution we will retrace the main steps of the IPCC’s preferred accounting system and compare this with our own advanced two-layer climate model (2LCM), which is especially appropriate to calculate the influence of increasing CO2 concentrations on global warming as well as the impact of solar variations on the climate (Harde2014 [16])

Summary

Introduction

The Fifth Assessment Report (AR5) [1] of the Intergovernmental Panel on Climate Change (IPCC), a list of all abbreviations is found in the annex, announces new evidence of an anthropogenic climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes, and simulations using climate models. An important criterion for a validation, which mechanism might control such cloud changes, can be derived from model simulations, which include the solar anomaly over the last century and compare this directly with the observed global warming over this period These investigations indicate that due to the strong cloud feedback the observed warming over the last century can only satisfactorily be explained, attributing a significant fraction to the increased solar activity over this period (see Ziskin & Shaviv [11]; Vahrenholt & Luning [25]). Our simulations predict a solar contribution of about 60% and a CO2 induced contribution of 40% to global warming over the last century with an equilibrium climate sensitivity of 0.7∘C, which is almost a factor of five smaller than published in AR5

Radiative Forcing

Radiation Transfer Calculations

Assessment of CO2 Global Warming

Findings

Solar Influence

Conclusion