The atmospheric temperatures and concentrations of Earth's five most important, greenhouse gases, H$_2$O, CO$_2$, O$_3$, N$_2$O and CH$_4$ control the cloud-free, thermal radiative flux from the Earth to outer space. Over 1/3 million lines having strengths as low as $10^{-27}$ cm of the HITRAN database were used to evaluate the dependence of the forcing on the gas concentrations. For a hypothetical, optically thin atmosphere, where there is negligible saturation of the absorption bands, or interference of one type of greenhouse gas with others, the per-molecule forcings are of order $10^{-22}$ W for H$_2$O, CO$_2$, O$_3$, N$_2$O and CH$_4$. For current atmospheric concentrations, the per-molecule forcings of the abundant greenhouse gases H$_2$O and CO$_2$ are suppressed by four orders of magnitude. The forcings of the less abundant greenhouse gases, O$_3$, N$_2$O and CH$_4$, are also suppressed, but much less so. For current concentrations, the per-molecule forcings are two to three orders of magnitude greater for O$_3$, N$_2$O and CH$_4$, than those of H$_2$O or CO$_2$. Doubling the current concentrations of CO$_2$, N$_2$O or CH$_4$ increases the forcings by a few per cent. These forcing results are close to previously published values even though the calculations did not utilize either a CO$_2$ or H$_2$O continuum. The change in surface temperature due to CO$_2$ doubling is estimated taking into account radiative-convective equilibrium of the atmosphere as well as water feedback for the cases of fixed absolute and relative humidities as well as the effect of using a pseudoadiabatic lapse rate to model the troposphere temperature. Satellite spectral measurements at various latitudes are in excellent quantitative agreement with modelled intensities.
We discuss how greenhouse gases affect radiation transfer in Earth's atmosphere. We explain how greenhouse gases like water vapor or carbon dioxide, differ from non-greenhouse gases like nitrogen or oxygen. Using simple thermodynamics and fluid mechanics, we show that a planet with sufficiently high concentrations of greenhouse gases must develop a convecting troposphere. The planet must also develop a non-convecting stratosphere above the tropopause. In the simplest approximation of an atmosphere that is transparent to sunlight and has frequency-independent opacity for thermal radiation, one …
Climate change is a result of a complex system of interactions of greenhouse gases (GHG), the ocean, land, ice, and clouds. Large climate change models use several computers and solve several equations to predict the future climate. The equations may include simple polynomials to partial differential equations. Because of the uptake mechanism of the land and ocean, greenhouse gas emissions can take a while to affect the climate. The IPCC has published reports on how greenhouse gas emissions may affect the average temperature of the troposphere and the predictions show that by the end of the ce…
The forcings due to changing concentrations of Earth's five most important, naturally occurring greenhouse gases, H$_2$O, CO$_2$, O$_3$, N$_2$O and CH$_4$ as well as CF$_4$ and SF$_6$ were evaluated for the case of a cloud-free atmosphere. The calculation used over 1.5 million lines having strengths as low as $10^{-27}$ cm. For a hypothetical, optically thin atmosphere, where there is negligible saturation of the absorption bands, or interference of one type of greenhouse gas with others, the per-molecule forcings are of order $10^{-22}$ Watts for H$_2$O, CO$_2$, O$_3$, N$_2$O and CH$_4$ and o…
A set of idealized experiments are performed to analyze the competing effects of declining atmospheric CO2 concentrations, the opening of an ocean gateway, and varying orbital parameters. These forcing mechanisms, which influence the global mean climate state, may have played a role for triggering climate transitions of the past (for example during the Eocene-Oligocene climate transition and the build-up of the Antarctic Ice Sheet). Sensitivity simulations with a coupled atmosphere-ocean general circulation model are conducted to test these three forcings and their roles for the global climate…
Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar of atmospheric N2. For CO2 to resolve the FYSP alone at 2…
This paper aims to better understand why there was a global warming pause in 2000-2015 and why the global mean surface temperature (GMST) has risen again in recent years. We present and statistically analyze substantial time-series observed datasets of global lower stratospheric temperature (GLST), troposphere-stratosphere temperature climatology, global land surface air temperature, GMST, sea ice extent (SIE) and snow cover extent (SCE), combined with modeled calculations of GLSTs and GMSTs. The observed and analyzed results show that GLST/SCE has stabilized since the mid-1990s with no signif…
How strong are quantitative contributions of the key natural modes of climate variability and the anthropogenic factor characterized by the changes of the radiative forcing of greenhouse gases in the atmosphere to the trends of the surface air temperature at different latitudes of the Northern and Southern Hemispheres on various time intervals? Such contributions to trends are estimated here from observation data with the simplest empirical models. Trivariate autoregressive models are fitted to the data since the 19th century and used to assess the impact of the anthropogenic forcing together …
Higher concentrations of atmospheric nitrous oxide (N2O) are expected to slightly warm Earth's surface because of increases in radiative forcing. Radiative forcing is the difference in the net upward thermal radiation flux from the Earth through a transparent atmosphere and radiation through an otherwise identical atmosphere with greenhouse gases. Radiative forcing, normally measured in W/m^2, depends on latitude, longitude and altitude, but it is often quoted for the tropopause, about 11 km of altitude for temperate latitudes, or for the top of the atmosphere at around 90 km. For current conc…
Social Cost of Greenhouse Gases -- OPTiMEM and the Heat Conjecture(s)
Butterfly Sciences（蝴蝶科学）；Institute of Arctic and Alpine Research, University of Colorado Boulder（科罗拉多大学博尔德分校北极与高山研究所）；Global Monitoring Laboratory, National Oceanic and Atmospheric Administration（美国国家海洋和大气管理局全球监测实验室）；Center for Ecosystem Science and Society, Northern Arizona University（北亚利桑那大学生态系统科学与社会中心）；London Institute of Banking and Finance（伦敦银行与金融学院）；Climate Central（气候中心）；NOAA/NESDIS/NCEI（美国国家海洋和大气管理局国家环境卫星、数据和信息服务中心）
Soil has been recognized as an indirect driver of global warming by regulating atmospheric greenhouse gases. However, in view of the higher heat capacity and CO2 concentration in soil than those in atmosphere, the direct contributions of soil to greenhouse effect may be non-ignorable. Through field manipulation of CO2 concentration both in soil and atmosphere, we demonstrated that the soil-retained heat and its slow transmission process within soil may cause slower heat leaking from the earth. Furthermore, soil air temperature was non-linearly affected by soil CO2 concentration with the highes…
Increasing greenhouse gases will change many aspects of the Earth's climate, from its annual mean to the frequency of extremes such as heat waves and droughts. Here we report that the current generation of climate models predicts a delay in the seasonal cycle of global rainfall and ocean temperature in response to increasing greenhouse gases, with important implications for the regional monsoons. In particular, the rainy season of the semi-arid African Sahel is projected to start later and become shorter: an undesirable change for local rainfed agriculture and pastoralism. Previous work has hi…
The contribution of anthropogenic and natural greenhouse gases to the atmosphere from the territory of Russia, China, USA and Canada to global climate change under different scenarios of anthropogenic emissions in the 21st century has been assessed. It is shown that the consideration of the changes in climate conditions can affect the impact indicators of greenhouse gas emissions on the climate system, especially over long time horizons. In making decisions, it is necessary to take into account that the role of natural fluxes of greenhouse gases into the atmosphere from the terrestrial ecosyst…
This study is focused on the effects of cosmic rays (solar activity) and halogenated molecules (mainly chlorofluorocarbons-CFCs) on atmospheric O3 depletion and global climate change. Brief reviews are first given on the cosmic-ray-driven electron-induced-reaction (CRE) theory for O3 depletion and the warming theory of CFCs for climate change. Then natural and anthropogenic contributions are examined in detail and separated well through in-depth statistical analyses of comprehensive measured datasets. For O3 loss, new statistical analyses of the CRE equation with observed data of total O3 and …
The present earth warming up is often explained by the atmosphere gas greenhouse effect. This explanation is in contradiction with the thermodynamics second law. The warming up by greenhouse effect is quite improbable. It is cloud reflection that gives to the earth s ground its 15 degres C mean temperature. Since the reflection of the radiation by gases is negligible, the role of the atmosphere greenhouse gases in the earth warming up by earth radiation reflection loses its importance. We think that natural climatic oscillations contribute more to earth climatic disturbances. The oscillation t…
The ultimate climate emergency is a "runaway greenhouse": a hot and water vapour rich atmosphere limits the emission of thermal radiation to space, causing runaway warming. Warming ceases only once the surface reaches ~1400K and emits radiation in the near-infrared, where water is not a good greenhouse gas. This would evaporate the entire ocean and exterminate all planetary life. Venus experienced a runaway greenhouse in the past, and we expect that Earth will in around 2 billion years as solar luminosity increases. But could we bring on such a catastrophe prematurely, by our current climate-a…
A Bridge Between Climate Science and Economics: OPTiMEM and the Heat Conjecture for Estimation of Social Cost of Greenhouse Gases
Butterfly Sciences（蝴蝶科学）；Institute of Arctic and Alpine Research, University of Colorado（科罗拉多大学极地高山研究所）；Center for Ecosystem Science and Society, Northern Arizona University（北亚利桑那大学生态系统科学与社会中心）；Chartered Governance Institute（特许治理学会）；Institute for Strategy, Resilience & Security, University College London（伦敦大学学院战略、韧性与安全研究所）；Climate Central（气候中心）
Carbon Dioxide (CO2) is one of the most important greenhouse gases after water vapor (H2O) which plays significant role in the climate process. Accurate space-based measurement of CO2 is of great significance in inferring the location of CO2 sources and sinks. Uncertainties in greenhouse gases (GHG) retrieval process must be minimized to accurately infer the actual amount of the atmospheric species. Clouds pose a large uncertainty in CO2 space-based retrieval process leading, mostly, to an underestimation in the CO2 absorption amount above the cloud layer provided that photons do not perform m…
Emission metrics, a crucial tool in setting effective equivalences between greenhouse gases, currently require a subjective, arbitrary choice of time horizon. Here, we propose a novel framework that uses a specific temperature goal to calculate the time horizon that aligns with scenarios achieving that temperature goal. We analyze the Intergovernmental Panel on Climate Change Special Report on Global Warming of 1.5 C Scenario Database to find that time horizons that align with the 1.5 and 2 C global warming goals of the Paris Agreement are 24 [90% prediction interval: 7, 41] and 58 [90% PI: 41…
