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Southern Ocean warming and Antarctic ice shelf melting in conditions plausible by late 23rd century in a high-end scenario

Ocean Science
DOI 10.5194/os-19-1595-2023
17 November 2023

How much the Antarctic ice shelf basal melt rate can increase in response to global warming remains an open question. To achieve this, we compared an ocean simulation under present-day atmospheric condition to a one under late 23rd century atmospheric conditions. The ocean response to the perturbation includes a decrease in the production of cold dense water and an increased intrusion of warmer water onto the continental shelves. This induces a substantial increase in ice shelf basal melt rates.

Universal differential equations for glacier ice flow modelling

We developed a new modelling framework combining numerical methods with machine learning. Using this approach, we focused on understanding how ice moves within glaciers, and we successfully learnt a prescribed law describing ice movement for 17 glaciers worldwide as a proof of concept. Our framework has the potential to discover important laws governing glacier processes, aiding our understanding of glacier physics and their contribution to water resources and sea-level rise.

Machine learning for numerical weather and climate modelling: a review

Machine learning (ML) is an increasingly popular tool in the field of weather and climate modelling. While ML has been used in this space for a long time, it is only recently that ML approaches have become competitive with more traditional methods. In this review, we have summarized the use of ML in weather and climate modelling over time; provided an overview of key ML concepts, methodologies, and terms; and suggested promising avenues for further research.

ESD Ideas: Arctic amplification’s contribution to breaches of the Paris Agreement

The Arctic is warming several times faster than the rest of the planet. Here, we use climate model projections to quantify for the first time how this faster warming in the Arctic impacts the timing of crossing the 1.5 °C and 2 °C thresholds defined in the Paris Agreement. We show that under plausible emissions scenarios that fail to meet the Paris 1.5 °C target, a hypothetical world without faster warming in the Arctic would breach that 1.5 °C target around 5 years later.

Opinion: A critical evaluation of the evidence for aerosol invigoration of deep convection

As atmospheric particles called aerosols increase in number, the number of droplets in clouds tends to increase, which has been theorized to increase storm intensity. We critically evaluate the evidence for this theory, showing that flaws and limitations of previous studies coupled with unaddressed cloud process complexities draw it into question. We provide recommendations for future observations and modelling to overcome current uncertainties.

Mechanisms controlling giant sea salt aerosol size distributions along a tropical orographic coastline

Sea salt aerosol is an important marine aerosol that may be produced in greater quantities in coastal regions than over the open ocean. This study observed these particles along the windward coastline of O’ahu, Hawai’i, to understand how wind and waves influence their production and dispersal. Overall, wave heights were the strongest variable correlated with changes in aerosol concentrations, while wind speeds played an important role in their horizontal dispersal and vertical mixing.

Rate-induced tipping in ecosystems and climate: the role of unstable states, basin boundaries and transient dynamics

Many systems in nature are characterized by the coexistence of different stable states for given environmental parameters and external forcing. Examples can be found in different fields of science, ranging from ecosystems to climate dynamics. Perturbations can lead to critical transitions (tipping) from one stable state to another. The study of these transitions requires the development of new methodological approaches that allow for modelling, analysing and predicting them.

N2O as a regression proxy for dynamical variability in stratospheric trace gas trends

This paper presents a technique for understanding the causes of long-term changes in stratospheric composition. By using N2O as a proxy for stratospheric circulation in the model used to calculated trends, it is possible to separate the effects of dynamics and chemistry on observed trace gas trends. We find that observed HCl increases are due to changes in the stratospheric circulation, as are O3 decreases above 30 hPa in the Northern Hemisphere.

Opinion: Recent developments and future directions in studying the mesosphere and lower thermosphere

The mesosphere or lower thermosphere region of the atmosphere borders the edge of space. It is subject to extreme ultraviolet photons and charged particles from the Sun and atmospheric gravity waves from below, which tend to break in this region. The pressure is very low, which facilitates chemistry involving species in excited states, and this is also the region where cosmic dust ablates and injects various metals. The result is a unique and exotic chemistry.

ESD Ideas: Translating historical extreme weather events into a warmer world

Adapting to climate change requires an understanding of how extreme weather events are changing. We propose a new approach to examine how the consequences of a particular weather pattern have been made worse by climate change, using an example of a severe windstorm that occurred in 1903. When this storm is translated into a warmer world, it produces higher wind speeds and increased rainfall, suggesting that this storm would be more damaging if it occurred today rather than 120 years ago.

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