Highlight articles

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This page features highlight articles from EGU's open access journals Climate of the Past, Earth System Dynamics, Geoscientific Model Development and Weather and Climate Dynamics. These articles of particular interest are selected by journal editors.

174 items found

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ESD Ideas: Why are glaciations slower than deglaciations?

Here we explore ancient climate transitions from warm periods to ice ages and from ice ages to warm periods of the last 400 000 years. The changeovers from warm to ice age conditions are slower than those from ice age to warm conditions. We propose the presence of strong negative sea–ice feedbacks may be responsible for slowing the transition from warm to full ice age conditions. By improving understanding of past abrupt changes, we may have improved knowledge of future system behavior.

Two types of North American droughts related to different atmospheric circulation patterns

The western USA is frequently affected by multiannual summer droughts. They can be separated into two groups with distinct spatial patterns. This study analyzes the atmospheric circulation during multiannual droughts in a new 3-D climate reconstruction. We confirm two distinct drought types differing with respect to atmospheric circulation as well as sea surface temperatures. Our results suggest that both the Pacific and the extratropical North Atlantic region affect North American droughts.

A comparative assessment of the uncertainties of global surface ocean CO2 estimates using a machine-learning ensemble (CSIR-ML6 version 2019a) – have we hit the wall?

The ocean plays a vital role in mitigating climate change by taking up atmospheric carbon dioxide (CO₂). Historically sparse ship-based measurements of surface ocean CO₂make direct estimates of CO₂exchange changes unreliable. We introduce a machine-learning ensemble approach to fill these observational gaps. Our method performs incrementally better relative to past methods, leading to our hypothesis that we are perhaps reaching the limitation of machine-learning algorithms’ capability.

Societal breakdown as an emergent property of large-scale behavioural models of land use change

Concerns are growing that human activity will lead to social and environmental breakdown, but it is hard to anticipate when and where such breakdowns might occur. We developed a new model of land management decisions in Europe to explore possible future changes and found that decision-making that takes into account social and environmental conditions can produce unexpected outcomes that include societal breakdown in challenging conditions.

Can we use sea surface temperature and productivity proxy records to reconstruct Ekman upwelling?

We test two assumptions that are often made in paleoclimate studies by using observations and ask whether temperature and productivity proxy records in the Southern California Current can be used to reconstruct Ekman upwelling. By examining the covariation between alongshore wind stress, temperature, and productivity, we found that the dominant covarying pattern does not reflect Ekman upwelling. Other upwelling patterns found are timescale dependent. Multiple proxies can improve reconstruction.

Meeting climate targets by direct CO2 injections: what price would the ocean have to pay?

This modeling study is the first one to look at the suitability and collateral effects of direct CO₂injection into the deep ocean as a means to bridge the gap between CO₂emissions and climate impacts of an intermediate CO₂emission scenario and a temperature target on a millennium timescale, such as the 1.5 °C climate target of the Paris Agreement.

Evaluating climate emulation: fundamental impulse testing of simple climate models

Simple climate models (SCMs) underlie many important scientific and decision-making endeavors. This illustrates the need for their use to be rooted in a clear understanding of their fundamental responses. In this study, we provide a comprehensive assessment of model performance by evaluating the fundamental responses of several SCMs. We find biases in some responses, which have implications for decision science. We conclude by recommending a standard set of validation tests for any SCM.

Effects of land use and anthropogenic aerosol emissions in the Roman Empire

Using the global aerosol–climate model ECHAM-HAM-SALSA, the effect of humans on European climate in the Roman Empire was quantified. Both land use and novel estimates of anthropogenic aerosol emissions were considered. We conducted simulations with fixed sea-surface temperatures to gain a first impression about the anthropogenic impact. While land use effects induced a regional warming for one of the reconstructions, aerosol emissions led to a cooling associated with aerosol–cloud interactions.

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 1: Model description

Our paper describes the Ecosystem Demography model. This computer program calculates how plants and ground exchange heat, water, and carbon with the air, and how plants grow, reproduce and die in different climates. Most models simplify forests to an average big tree. We consider that tall, deep-rooted trees get more light and water than small plants, and that some plants can with shade and drought. This diversity helps us to better explain how plants live and interact with the atmosphere.

The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: the Ecosystem Demography model, version 2.2 – Part 2: Model evaluation for tropical South America

The Ecosystem Demography model calculates the fluxes of heat, water, and carbon between plants and ground and the air, and the life cycle of plants in different climates. To test if our calculations were reasonable, we compared our results with field and satellite measurements. Our model predicts well the extent of the Amazon forest, how much light forests absorb, and how much water forests release to the air. However, it must improve the tree growth rates and how fast dead plants decompose.

CL Climate: Past, Present & Future Highlight articles