Worster Drought Syndrome

Climate change is aggravating the impact of droughts -- one of the factors that only affect plant physiology -- on all plant ecosystems worldwide. Although new tools have been developed to detect and assess drought stress in plants -- transcriptomic or metabolomic technologies, etc. -- they are still difficult to apply in natural ecosystems, especially in remote areas and developing countries. Climate change is aggravating the impact of droughts -- one of the factors that only affect plant physiology -- on all plant ecosystems worldwide. Although new tools have been developed to detect and assess drought stress in plants -- transcriptomic or metabolomic technologies, etc. -- they are still difficult to apply in natural ecosystems, especially in remote areas and developing countries. Now, a study published in the journal Trends in Plant Science presents a set of techniques that enable researchers to detect and monitor drought stress in plants in a cheap, easy and quick way. The authors of the study are the experts Sergi Munné-Bosch and Sabina Villadangos, from the Faculty of Biology and the Institute for Research on Biodiversity (IRBio) of the University of Barcelona. Fighting the impact of drought on plants The techniques available to detect and monitor the effects of drought stress in plants range from very simple and inexpensive measures (growth or relative water content analysis) to more complex and expensive approaches (omics technologies). UB professor Sergi Munné-Bosch, professor in the Department of Evolutionary Biology, Ecology and Environmental Sciences, explains that these innovative technologies "have provided new opportunities to detect and monitor drought stress, but their cost generates inequalities around the world." "Unfortunately -- he continues -- today the whole world is affected by the lack of water resources, especially in the context of the current climate change we are experiencing. And, unfortunately, countries with fewer economic resources are no exception. It should be borne in mind that most of the poorest countries are in Africa, which is also home to the world's largest arid and sub-arid regions." Laboratories with basic equipment The study aims to respond to the need to establish effective and low-cost protocols to easily detect and study how droughts affect plants. Specifically, the authors present a battery of very accessible techniques that can be applied with basic laboratory equipment: precision balance, microscope, centrifuge, spectrophotometer, oven, camera and computer. These laboratories could analyse different parameters on growth rates, leaf water content, pigments and leaf viability using the tetrazolium test, an organic heterocyclic compound that has traditionally been used in plant physiology studies. "With these indicators, we can get a complete picture of which species are best adapted to a particular climate, or how a given crop responds to changing conditions in a given region in the current context of climate change," says Munné-Bosch. "All these measures are easy to conduct. In addition, a specialised team can be assembled in a very short time to develop measures quickly and efficiently. And they can be implemented at a very low cost, so they are viable approaches worldwide," says the researcher. The tetrazolium test: getting a classic back In a second study (Trends in Plant Science, 2023), the team highlights the use of the tetrazolium test as a useful and easy-to-apply method for evaluating the effects of drought stress on plants. "This test not only allows us to detect whether a cell, tissue or organ is alive or dead, but it is also an excellent indicator of its longevity; in other words, it is a scientific tool that allows us to predict how long a plant will live. This can be especially useful for biodiversity management and conservation programmes, especially in the current context of climate change," says the researcher. The impact of climate change is stimulating research into how plants adapt to new environmental conditions. "More than a stimulus, this is a necessity. Humans need to adapt to climate change, and they will always do so better hand in hand with nature, integrating with it. And to do so, it is essential to know the ecosystems and all the organisms that form part of them, including plants," says Munné-Bosch. Designing and implementing quality scientific tools is determining to create management plans and to conserve the biodiversity worldwide. "This study contributes to a better understanding of the plants' response to drought in a context of climate change, and, in addition, it can be useful for biodiversity management programmes," notes the UB researcher Sabina Villadangos. The study also makes it easier for these measures to be implemented worldwide. "It is necessary to bear in mind that if all countries do not coordinate in the face of foreseeable changes, the effects of global change will be devastating," concludes Sergi Munné-Bosch.

Researchers now have a much better understanding of how climate change can impact and cause sea water temperatures on one side of the Indian Ocean to be so much warmer or cooler than the temperatures on the other -- a phenomenon that can lead to sometimes deadly weather-related events like megadroughts in East Africa and severe flooding in Indonesia. With a new analysis of long-term climate data, researchers say they now have a much better understanding of how climate change can impact and cause sea water temperatures on one side of the Indian Ocean to be so much warmer or cooler than the temperatures on the other -- a phenomenon that can lead to sometimes deadly weather-related events like megadroughts in East Africa and severe flooding in Indonesia. The analysis, described in a new study in Science Advances by an international team of scientists led by researchers from Brown University, compares 10,000 years of past climate conditions reconstructed from different sets of geological records to simulations from an advanced climate model. The findings show that about 18,000 to 15,000 years ago, as a result of melted freshwater from the massive glacier that once covered much of North America pouring into the North Atlantic, ocean currents that kept the Atlantic Ocean warm weakened, setting off a chain of events in response. The weakening of the system ultimately led to the strengthening of an atmospheric loop in the Indian Ocean that keeps warmer water on one side and cooler water on the other. This extreme weather pattern, known as a dipole, prompts one side (either east or west) to have higher-than-average rainfall and the other to have widespread drought. The researchers saw examples of this pattern in both the historical data they studied and the model's simulation. They say the findings can help scientists not only better understand the mechanisms behind the east-west dipole in the Indian Ocean, but can one day help to produce more effective forecasts of drought and flood in the region. "We know that in the present-day gradients in the temperature of the Indian Ocean are important to rainfall and drought patterns, especially in East Africa, but it's been challenging to show that those gradients change on long time-scales and to link them to long-term rainfall and drought patterns on both sides of the Indian Ocean," said James Russell, a study author and professor of Earth, environmental, and planetary sciences at Brown. "We now have a mechanistic basis to understand why some of the longer-term changes in rainfall patterns in the two regions have changed through time." In the paper, the researchers explain the mechanisms behind how the Indian Ocean dipole they studied formed and the weather-related events it led to during the period they looked at, which covered the end of the last Ice Age and the start of the current geological epoch. The researchers characterize the dipole as an east-west dipole where the water on the western side -- which borders modern day East African countries like Kenya, Ethiopia and Somalia -- is cooler than the water on eastern side toward Indonesia. They saw that the warmer water conditions of the dipole brought greater rainfall to Indonesia, while the cooler water brought much drier weather to East Africa. That fits into what is often seen in recent Indian Ocean dipole events. In October, for example, heavy rain led to floods and landslides in Indonesian islands of Java and Sulawesi, leaving four people dead and impacting over 30,000 people. On the opposite end, Ethiopia, Kenya and Somalia experienced intense droughts starting in 2020 that threatened to cause famine. The changes the authors observed 17,000 years ago were even more extreme, including the complete drying of Lake Victoria -- one of the largest lakes on Earth. "Essentially, the dipole intensifies dry conditions and wet conditions that could result in extreme events like multi-year or decades-long dry events in East Africa and flooding events in South Indonesia," said Xiaojing Du, a Voss postdoctoral researcher in the Institute at Brown for Environment and Society and Brown's Department of Earth, Environmental and Planetary Sciences, and the study's lead author. "These are events that impact people's lives and also agriculture in those regions. Understanding the dipole can help us better predict and better prepare for future climate change." The dipole the researchers studied formed from the interactions between the heat transport system of the Atlantic Ocean and an atmospheric loop, called a Walker Circulation, in the tropical Indian Ocean. The lower part of the atmospheric loop flows east to west across much of the region at low altitudes near the ocean surface, and the upper part flows west to east at higher altitudes. The higher air and lower air connect in one big loop. Interruption and weakening of the Atlantic Ocean heat transport, which works like a conveyor belt made of ocean and wind currents, was brought on by massive melting of the Laurentide ice sheet that once covered most of Canada and the northern U.S. The melting cooled the Atlantic and consequent wind anomalies triggered the atmospheric loop over the tropical Indian Ocean to become more active and extreme. That then led to increased precipitation in the east side of the Indian Ocean (where Indonesia sits) and reduced precipitation in the west side, where East Africa sits. The researchers also show that during the period they studied, this effect was amplified by a lower sea level and the exposure of nearby continental shelves. The scientists say more research is needed to figure out exactly what effect the exposed continental shelf and lower sea level has on the Indian Ocean's east-west dipole, but they're already planning to expand the work to investigate the question. While this line of the work on lower sea levels won't play into modeling future conditions, the work they've done investigating how the melting of ancient glaciers impacts the Indian Ocean dipole and the heat transport system of the Atlantic Ocean may provide key insights into future changes as climate change brings about more melting. "Greenland is currently melting so fast that it's discharging a lot of freshwater into the North Atlantic Ocean in ways that are impacting the ocean circulation," Russell said. "The work done here has provided a new understanding of how changes in the Atlantic Ocean circulation can impact Indian Ocean climate and through that rainfall in Africa and Indonesia." The study was supported with funding from the Institute at Brown for Environment and Society and the National Science Foundation.

The El Niño phenomenon influences the weather in distant regions, as far away as the USA, India or the Mediterranean region. But how exactly these so-called teleconnections actually work has not yet been clarified completely. Atmospheric researchers at have now succeeded in demonstrating that variations of the transport of air mass, heat, moisture and energy from the tropical Pacific are responsible for many of these climate anomalies. And: El Niño also warms up the Atlantic. The El Niño phenomenon influences the weather in distant regions, as far away as the USA, India or the Mediterranean region. But how exactly these so-called teleconnections actually work has not yet been clarified completely. Atmospheric researchers at the University of Vienna have now succeeded in demonstrating that variations of the transport of air mass, heat, moisture and energy from the tropical Pacific are responsible for many of these climate anomalies. And: El Niño also warms up the Atlantic, according to the study recently published in the journal Geophysical Research Letters. The El Niño Southern Oscillation (ENSO) is one of the most important modes of climate variability worldwide, with large impacts on the weather conditions in many regions, and thus on agriculture and economy. It is related to changes in the sea surface temperatures in the Tropical Pacific Ocean. Periods with higher temperatures cause the so-called El Niño phenomenon. This phenomenon causes pronounced weather anomalies in many regions around the world, for example, droughts in the Amazon basin. These far-ranging impacts are called teleconnections. Breakthrough regarding the role of air mass transport Despite of a lot of research that has been done on ENSO, the mechanisms behind the observed teleconnections are still not well understood. Researchers at the University of Vienna now made a breakthrough in our understanding of the role of air mass transport in these teleconnections. They found that variations of the transport of air mass, heat, moisture and energy from the Tropical Pacific are causally responsible for many of the observed climate anomalies. Katharina Baier, first author of the study and Early Career Researcher at the Department of Meteorology and Geophysics of the University of Vienna, explains: "The main benefit of our study is the different perspective on teleconnections, as we look at how the heat and moisture from the Pacific Ocean is transported via the atmosphere. We can thus establish a direct connection between the Pacific and remote regions. For instance, we can show that anomalously dry air is transported towards the Amazon Basin during El Niño, causing droughts there. In contrast, anomalously moist air is transported toward the southeastern U.S., which favours increased precipitation." El Niño is also warming the Atlantic ocean Andreas Stohl from the University of Vienna, who has led the study which is now published in the journal Geophysical Research Letters, points out: "Our results contribute to the understanding of weather phenomena worldwide, for instance also in Australia, Africa, or the Mediterranean. In addition, we can show that anomalously large amounts of heat are transported from the Tropical Pacific towards the Atlantic Ocean during El Niño, which then responds by warming." Stohl is also head of the Department of Meteorology and Geophysics as well as the Research Network "VINAR." Methodologically, the research team at the University of Vienna relied on atmospheric dispersion models, the so-called Lagrangian models. While conventional models record meteorological parameters such as humidity or temperature at certain positions, Lagrangian models follow the individual particles and capture how the meteorological parameters change along their way. These models can also be used to analyze the dispersion of particles such as soot, microplastics, or greenhouse gases.