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Surface buoyancy control of millennial-scale variations in the Atlantic meridional ocean circulation

Using an Earth system model that can simulate Dansgaard–Oeschger-like events, we show that conditions under which millennial-scale climate variability occurs are related to the integrated surface buoyancy flux over the northern North Atlantic. This newly defined buoyancy measure explains why millennial-scale climate variability arising from abrupt changes in the Atlantic meridional overturning circulation occurred for mid-glacial conditions but not for interglacial or full glacial conditions.

Lidar measurements of noctilucent clouds at Río Grande, Tierra del Fuego, Argentina

Noctilucent clouds (NLCs) are silvery clouds that can be viewed during twilight and indicate atmospheric conditions like temperature and water vapor in the upper mesosphere. High-resolution measurements from a remote sensing laser instrument provide NLC height, brightness, and occurrence rate since 2017. Most observations occur in the morning hours, likely caused by strong tidal winds, and NLC ice particles are thus transported from elsewhere to the observing location in the Southern Hemisphere.

Channel concavity controls planform complexity of branching drainage networks

To explore the pattern formed by rivers as they crisscross the land, we developed a way to measure how these patterns vary, from straight to complex, winding paths. We discovered that a river’s degree of complexity depends on how the river slope changes downstream. Although this is strange (i.e., why would changes in slope affect twists of a river in map view?), we show that this dependency is almost inevitable and that the complexity could signify how arid the climate is or used to be.

Opinion: Challenges and needs of tropospheric chemical mechanism development

Chemical mechanisms describe the chemical processes in atmospheric models that are used to describe the changes in the atmospheric composition. Therefore, accurate chemical mechanisms are necessary to predict the evolution of air pollution and climate change. The article describes all steps that are needed to build chemical mechanisms and discusses the advances and needs of experimental and theoretical research activities needed to build reliable chemical mechanisms.

Exploring drought hazard, vulnerability, and related impacts on agriculture in Brandenburg

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-24-4237-2024
5 December 2024

Droughts are a threat to agricultural crops, but different factors influence how much damage occurs. This is important to know to create meaningful risk maps and to evaluate adaptation options. We investigate the years 2013–2022 in Brandenburg, Germany, and find in particular the soil quality and meteorological drought in June to be statistically related to the observed damage. Measurement of crop health from satellites is also related to soil quality and not necessarily to anomalous yields.

Weak liquid water path response in ship tracks

Ship emissions can form artificially brightened clouds, known as ship tracks, and provide us with an opportunity to investigate how aerosols interact with clouds. Previous studies that used ship tracks suggest that clouds can experience large increases in the amount of water (LWP) from aerosols. Here, we show that there is a bias in previous research and that, when we account for this bias, the LWP response to aerosols is much weaker than previously reported.

Modeling 2020 regulatory changes in international shipping emissions helps explain anomalous 2023 warming

On 1 January 2020, international shipping vessels were required to substantially reduce the amount of particulate they emit to improve air quality. In this work we demonstrate how this regulatory change contributed to the anomalous warming observed in recent months using climate model simulations that include such a change. Future policies should also perhaps consider their impact on climate, and climate modelers should promptly include those changes in future modeling efforts.

Cross-scale causal information flow from the El Niño–Southern Oscillation to precipitation in eastern China

The El Niño–Southern Oscillation (ENSO) is a gigantic natural orchestra playing with the temperature of Pacific waters and influencing air temperature and rainfall worldwide. Naturally, the “loudness” or amplitude of ENSO has effects on climate; however, consonance of its various tones, or phases of different ENSO oscillatory components, can exert causal effects on rainfall in some areas in China. In different regions, different aspects of ENSO dynamics can predict rainfall amounts.

Microbial response to deliquescence of nitrate-rich soils in the hyperarid Atacama Desert

We studied unique nitrate-rich soils in the hyperarid Atacama Desert that form brines at night under high relative humidity. Despite providing water for microorganisms, these soils exhibit extremely low microbial activity, indicating that the high nitrate levels inhibit microbial life. On the other hand, enriched organic matter indicates their potential preservation. This research helps to understand the limits of life in extreme environments and aids in the search for signs of life on Mars.

Microbial strong organic-ligand production is tightly coupled to iron in hydrothermal plumes

Hydrothermally derived iron can be transported kilometers away from deep-sea vents, representing a significant flux of vital micronutrients to the ocean. However, the mechanisms that support the stabilization of dissolved iron remain elusive. Using electrochemical, spectrometry, and genomic methods, we demonstrated that strong ligands exert an important control on iron in plumes, and high-affinity iron-binding siderophores were identified in several hydrothermal plume samples for the first time

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