It’s April again, the month when Europe’s largest geoscience union, EGU, convenes for its General Assembly in Vienna, Austria. This year, EGU-24 is scheduled to take place from 14 – 19 April 2024, and we are thrilled to be there and share our science. Our group will be contributing to several presentations, including those by Tejasvi, Sarosh, Axel, Pinhsin and Yinglin.
Tuesday morning, 16 April
Tejasvi will be giving a PICO presentation on Estimating the sensitivity of continental aridity to global warming using Budyko’s framework in session HS7.4 Future hydroclimatic scenarios in a changing world from 08:30–10:15 at PICO3.4. The talk focuses on estimating the sensitivity of continental aridity to global warming using the Budyko’s estimate of aridity — the ratio of potential evaporation to precipitation. We can analytically separate this sensitivity of this estimate into the difference between the sensitivities of potential evaporation and precipitation to temperature. Tejasvi then shows how the sensitivity of potential evaporation varies across different methods used for its estimation and that of precipitation varies across different datasets, leading to an uncertainty in the sensitivity of aridity with global warming. He further discusses the sensitivities of aridity for northern and southern hemisphere land regions in different seasons. Drop by at PICO Spot 3 on 16th April to know more about this work!
On Tuesday, 16 April 2024, from 11:25-11:35 in Room 0.94/0.95, Caterina Gozzi presents a talk on “Probability distributions as indicators of dissipative dynamics in river chemistry” in the session NP3.3 “Climate Variability & Complex System Analysis Across Scales”. Her talk is based on joint work from a longer-term effort between Antonella Buccianti‘s group at the University of Florence and Axel to link thermodynamics to probability distributions. It is motivated by the observation that environmental variables typically are either (log)normally distributed or follow power laws. We aim to link this to thermodynamics using observations of riverine chemistry of the Arno river basin in Central Italy as examples for such distributions. We then link the type of distribution to the dissipative nature of its weathering and mixing dynamics. We find that calcium and carbonate, geochemical species that are close to their thermodynamic equilibrium state of saturation, show lognormal distributions, while sodium and chloride are far from equilibrium and show power-law scaling behavior. What this implies is that the thermodynamic state of environmental variables is closely linked to their frequency distributions, and that the extent of disequilibrium constrains the range over which power-law scaling can be observed. The associated manuscript is currently in revision for Science of the Total Environment.
Wednesday afternoon, 17 April
Sarosh will be giving his 10 min talk at 14:35 in Room C on “Extreme precipitation – temperature scaling: disentangling causality and covariation” in the session NH1.2 – Extreme meteorological and hydrological events induced by severe weather and climate change. His talk will focus on estimating the sensitivity of precipitation extremes from observations at a global scale. Extreme precipitation is expected to increase with temperature at the same rate at which air can hold moisture. This is set by thermodynamics and is known as the saturation vapor pressure curve, or the Clausius Clapeyron (CC) equation, yielding a relative increase by about 7%/K. However, observations in tropical regions typically show precipitation – temperature scaling rates that are largely negative. Why is this so, and what can we learn from this for the response to global warming? Sarosh shows in his work that this negative scaling arises from the cooling effect of clouds on surface temperature which adds a covariation between rainfall and temperature. Scaling rates derived from observations thus not only represent how precipitation changes with temperature, but also how precipitation affects temperatures through changes in the radiative forcing. Sarosh uses an energy balance model constrained by thermodynamic limit of maximum power to separate the effect of clouds on surface temperature. He then shows that extreme precipitation actually shows a positive scaling with temperature consistent with the CC rate once the effect of clouds is accounted for. To know more about his work, attend his talk and/or contact him here.
Axel talks on Wednesday afternoon from 16:20-16:30 in Room 1.34, about “Follow the energy: Why using more offshore wind power weakens ocean dynamics and impacts marine ecosystems” in session OS4.6 on “Ocean renewable energy: resource characterization, bio-physical interactions, and societal impacts“. This talk is a follow-up on joint work with Jake Badger’s group at DTU Wind Energy on offshore wind resource estimation in the German bight region of the North sea. The idea is simple: When offshore wind energy is expanded and wind turbines use more of the wind energy to generate electricity, less wind is left, reducing surface friction and thus the wind energy input into the ocean. This has consequences in terms of less waves, less dynamics, and less mixing – effects that to some extent are already observed downwind of existing offshore wind farms. Since marine productivity is closely linked to mixing, an expansion of offshore wind energy will have its detrimental impacts on marine ecosystems. This line of “following the energy” is illustrated in magnitude using a 150 GW scenario for the North sea, as formulated by the Esbjerg declaration. An associated manuscript describing this research is currently in revision.
Thursday, 18 April
You can meet Axel during the “Meet the Editors of Earth System Dynamics” session at the EGU booth in Hall X2 from 10:00-11:00. Feel free to drop by!
Friday, 19 April
Pinhsin talks on Friday morning from 11:40-11:50 about “Plant diversity-climate interactions from a modelling perspective” in session BG1.18 – The intertwined climate and biodiversity crises: cross-scale observational and modelling approaches in Room N2. She shows her modelling work in which she set up a new vegetation model JeDi-BACH into the land component of the ICON-Earth System Model (ICON-ESM) and incorporated a plant functional trade-off scheme developed by Kleidon and Mooney (2000). The advantage of this new model is that the representation of global vegetation is an emergent outcome of environmental filtering following several well-known fundamental functional trade-offs that link plant functions to abiotic and biotic attributes. In such a way, plants dynamically adjust to the changing environment and meanwhile modify climate. With this new model, Pinhsin presents a series of sensitivity studies investigating the effect of plant trait diversity on the coupled vegetation-climate system in a coupled land-atmosphere setup. She found that high plant diversity ecosystems tend to stabilize terrestrial climate in a high water-turnover state, leading to a wet and cool climate. These modeling results demonstrate the importance of the “biodiversity-climate feedback” and highlight the role of plant functional diversity in shaping a robust climate. A related manuscript is currently in preparation.
Yinglin will give a talk in the afternoon on “Global warming increases the proportion of more damaging heat extremes” in session NH11.2 – Future Changes in Weather and Climate Hazards around the World from 16:35-16:45. This is a joint work with Prof. Dr. Jakob Zscheischler’s group at UFZ about the varying mechanisms and consequently differing impacts and trends of summer heatwaves. Using a derivative approach based on surface energy balance, we categorize heatwaves in the past 42 years into four distinct types characterized by differing physical mechanisms, namely sunny-humid, sunny–dry, advective, and adiabatic heatwave-days. We find that sunny–dry heatwave-days are most detrimental to terrestrial vegetation, whereas advective heatwave-days pose the greatest hazard to human health. With state-of-the-art climate model projections under a high emission scenario, we conclude that the proportion of the two most detrimental heatwave types, i.e., sunny–dry and advective heatwave-days, will increase by 3.4% and 1.5% until the end of the century, respectively, while the proportion of other heatwave types will decrease. These results reveal extra risks besides the overall increase of heat extremes, i.e., the future is shifted toward a greater prevalence of high-impactful heat extremes under global warming. An associated manuscript describing this research is currently in revision.
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