Drought at Lake Zurich, a tomato field cooled by solar panels and climate effects on apples and wheat
Lake Zurich's water level fell to 404.45 metres amid drought. Elsewhere, a model showed agrivoltaic panels cutting leaf temperatures by 1.84 °C, while 35 years of harvest data revealed warming weather lowering wheat yields but supporting apples.
Science··Morning
Drought in Switzerland drives Lake Zurich near record lows
Switzerland's Federal Office for the Environment measured Lake Zurich at 404.45 metres above sea level on Wednesday. The previous low of 405.46 m was recorded in 1952, against an annual mean of 405.93 m. The country has faced marked drought since spring, with repeated heat waves and below-average rainfall. Lake Constance and Lake Maggiore have also fallen below their seasonal averages, though Lake Geneva remains near average because glacier melt still feeds it. The office attributes the readings, which forced the lake ferry to stop carrying heavy trucks, to dry soils and low surface water and groundwater levels, noting that conditions have worsened in recent weeks.[1]
Agrivoltaic panels cool plants but reduce carbon uptake
A model of an agrivoltaic farm showed tomato leaves under the panels averaged 1.84 °C cooler, with the difference peaking at 7.56 °C in the afternoon, while evapotranspiration fell 22.4 percent. Published in the Journal of Advances in Modeling Earth Systems, the study was validated against site data rather than measured on a working farm: it used leaf temperatures from Davis, California, and soil temperatures from Chicago City, Minnesota, for a hypothetical simulation at Princeton, New Jersey. The panels themselves ran 5.6 °C cooler during the day, recovering about 15 percent of the efficiency lost to heat, and perceived temperature for a field worker fell 4.46 °C. Under the panels, light dropped 47 percent and carbon uptake to fall 31 percent.[2]
A warming climate hits wheat harvests but boosts apple yields
Sara Leonhardt's group at the Technical University of Munich compared yields of wheat, apples, cherries, and rapeseed in Lower Franconia and Upper Bavaria over more than 35 years. According to the study published in Ecology and Evolution, wheat, which pollinates itself or by wind, yielded less when temperatures passed its optimum, producing smaller and fewer grains. Apples, which depend on insects, gained in yield because late frosts damaged fewer blossoms. The authors read this advantage as temporary, expecting further warming to press both the trees and their dependent insects. The research compares crop groups within two regions rather than establishing a general law on pollinator dependence, leading the authors to argue for hedgerows, varied rotations, and less pesticide.[3]
