We tried to represent atmospheric convection induced by radiative forcing with a simple climate model based on maximum entropy production. Contrary to previous models, we give a minimal description of energy transport in the atmosphere. It allows us to give better results in terms of temperature and vertical energy flux profiles.
Christoph Heinze, Veronika Eyring, Pierre Friedlingstein, Colin Jones, Yves Balkanski, William Collins, Thierry Fichefet, Shuang Gao, Alex Hall, Detelina Ivanova, Wolfgang Knorr, Reto Knutti, Alexander Löw, Michael Ponater, Martin G. Schultz, Michael Schulz, Pier Siebesma, Joao Teixeira, George Tselioudis, and Martin Vancoppenolle
Earth system models for producing climate projections under given forcings include additional processes and feedbacks that traditional physical climate models do not consider. We present an overview of climate feedbacks for key Earth system components and discuss the evaluation of these feedbacks. The target group for this article includes generalists with a background in natural sciences and an interest in climate change as well as experts working in interdisciplinary climate research.
We use the climate-economy model DICE to perform a cost–benefit analysis of sulfate geoengineering, i.e. producing a thin artificial sulfate haze in the higher atmosphere to reflect some sunlight and cool the Earth.
We find that geoengineering can increase future welfare by reducing global warming, and should be taken seriously as a policy option, but it can only complement, not replace, carbon emission reduction. The best policy is to combine CO2 emission reduction with modest geoengineering.
For local living conditions, it matters whether deforestation influences the surface temperature, temperature at 2 m, or the temperature higher up in the atmosphere. Here, simulations with a climate model show that at a location of deforestation, surface temperature generally changes more strongly than atmospheric temperature. Comparison across climate models shows that both for summer and winter the surface temperature response exceeds the air temperature response locally by a factor of 2.
We study the fine-scale structure of Tehuano winds in the Isthmus of Tehuantepec, focusing on the flow beyond the well-known strong gap wind jet. We use high-resolution WRF model simulations to show that different downslope windstorm conditions and hydraulic jumps with rotor circulations develop in the mountains east of Chivela Pass depending on crest height and thermodynamic conditions of the air mass. The intense turbulent flows can have a large impact on the existent wind farms in the region.
The concept of emergent constraints is a key method to reduce uncertainty in multi-model climate projections using historical simulations and observations. Here, we present an in-depth analysis of the applicability of the method and uncover possible limitations. Key limitations are a lack of comparability (temporal, spatial, and conceptual) between models and observations and the disagreement between models on system dynamics throughout different levels of atmospheric CO2 concentration.
The missing carbon sink is puzzling since carbon cycle is related to global climate. The varying characteristics of soil profile CO2 concentration in carbonate areas and noncarbonates were investigated, together with pH, SOC, and isotope. It is found that carbonate corrosion deeply consumes soil CO2, which accounts for an average of 36 %. Such a process is important for karst carbon cycles and global climate changes, and may be a potential part of the missing sink.
Oceanic deoxygenation is driven by climate change in several areas of the global ocean. Measurements indicate that ocean volumes with very low oxygen levels expand, with consequences for marine organisms and fishery. We found climate-change-driven phosphorus (P) input in the ocean is hereby an important driver for deoxygenation on longer timescales with effects in the next millennia.
We show how the complex dynamics of the jet stream at midlatitude can be described by a simple mathematical model. We match the properties of the model to those obtained by the jet data derived from observations.
Differences between a 1.5 and a 2.0 °C warmer global climate than 1850 conditions are discussed based on a suite of global atmosphere-only, fully coupled, and slab-ocean runs with the Norwegian Earth System Model. Responses, such as the Arctic amplification of global warming, are stronger with the fully coupled and slab-ocean configurations. While ice-free Arctic summers are rare under 1.5 °C warming in the slab-ocean runs, they are estimated to occur 18 % of the time under 2.0 °C warming.
We quantify the contributions of climate change and groundwater extraction to the trends in soil moisture through two groups of simulations. In summary, climate change dominates the soil moisture trends, while GW extraction accelerates or decelerates soil moisture trends under climate change. This work will improve our understanding of how human activities affect soil water content and will help to determine the mechanisms underlying the global water cycle.