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Tag: climate

  • When the Mediterranean Nearly Faced Total Extinction 6 Million Years Ago

    When the Mediterranean Nearly Faced Total Extinction 6 Million Years Ago

    Around 6 million years ago, the Mediterranean Sea experienced a drastic environmental change. Due to tectonic movements that closed the Gibraltar Strait, isolating it from the Atlantic Ocean, the Mediterranean underwent an unprecedented drying out. Under the effects of a hot and dry climate, the sea level gradually dropped, reaching a critical point.

    A Nearly Completely Dry Mediterranean Sea

    Approximately 5.5 million years ago, the Mediterranean basin resembled a vast depression, its floor occupied by hypersaline water.


    The landscape was similar to that of the current Dead Sea. In total, about 1 million cubic kilometers of salt are thought to have been deposited in the basin!

    One can imagine the dramatic repercussions of this drying out on marine biodiversity.


    However, the impact on ecosystems remains poorly constrained. A new study published in the journal Science has managed to quantify it. And to say the least, the Mediterranean’s marine ecosystems nearly faced extinction.

    A Total “Reset” of Biodiversity

    Out of the 2,006 endemic species recorded before the Messinian Crisis, only 86 survived this event. Fossil records show a 66.8% difference in species present before and after the crisis, which ended with the abrupt opening of the Gibraltar Strait 5.33 million years ago, allowing Atlantic waters to flood into the dried-up basin.

    The current Mediterranean ecosystems were primarily built upon the arrival of species from the Atlantic.

  • Hottest June Since Records Began — Last Year’s Record Broken

    Hottest June Since Records Began — Last Year’s Record Broken

  • The True Scale of the Carbon Impact of Long-Distance Travel Finally Revealed

    The True Scale of the Carbon Impact of Long-Distance Travel Finally Revealed

  • Why Don’t All Trees Lose Their Leaves in the Fall?

    Why Don’t All Trees Lose Their Leaves in the Fall?

    With the arrival of autumn, the leaves on most trees change color, becoming red, yellow, or brown. Oaks, beeches, and chestnuts turn entirely bare of leaves in a few weeks. However, conifers like firs, spruces, and other related species don’t appear to care much that fall, and winter are on the way. Even in the dead of winter, their needles maintain their vibrant green color. Although most shrubs lose their leaves in the autumn, evergreens are an exception. But why? As to why certain trees and shrubs lose their leaves while others do not, science comes to our aid for an explanation.

    Frosty Waters

    Most plants have trouble with both the cold and a lack of water throughout the winter. The freezing temperatures of winter prevent water from seeping through the ground.

    This water supply is further depleted during frost because deciduous plants, in particular, lose so much water via their leaves during photosynthesis.

    Because of this, plants with full foliage can essentially freeze to death. As a result, many deciduous trees totally shed their leaves to prevent this fate. During the barren winter months, this shedding of leaves prevents animals from eating the leaves.

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    Nitrogen Reserves

    However, the tree swiftly recycles all of the leaves it can use before they fall. It is no surprise that nitrogen is crucial for plant growth, and this includes nitrogenous protein-building components in particular.

    These components are broken down into water-soluble chemicals and sent to the plant’s main stem and roots as a kind of nutrition reserve.

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    As a result of this breakdown, the leaves retain traces of their yellow and red colors. Nitrogen is the reason for the vibrant foliage of fall.

    Budget-Friendly Conifers

    However, most conifers retain their foliage throughout the year. They have a wax covering on their needles, so they lose less water via their already dramatically decreased leaf area, making them better able to withstand drought and cold.

    In addition, stomata (tiny openings for gas exchange with the environment) in fir, spruce, and other trees are buried deep in needle cavities. As a result, they can manage to maintain their needle leaves while receiving just a little amount of water.

    Many conifers grow in regions where winters are long. Thus, they preserve their leaves because frost may still occur in early summer and is already occurring in early autumn, giving them a reason to wait it out.

    The time with enough brightness and warmth is insufficient to allow for the formation of leaves and, subsequently, to also collect enough energy for fruits and seeds. Thus, the trees decided not to shed their leaves in the first place.

    Both Coniferous and Deciduous Trees Have Exceptions

    Despite being a member of the conifer family, the larch also sheds its leaves. The larch is a conifer that thrives in extreme cold, such as in the high mountains and the far north.

    There, not even conifers’ natural resistance to cold is enough to ensure their survival. To prevent any more water loss throughout the winter, it decides to shed its leaves as the best strategy.

    However, evergreen foliage is not limited to conifers: Cherry laurel and rhododendron are two deciduous plants that keep their leaves throughout the winter.

    These crops are often sourced from warmer climates with shorter winters. Since this is the case, it is frequently not worth the effort for them to lose their old leaves and grow new ones each spring.

    Those plants hold on to their leaves rather than invest in replacing them. Climate has a major role in this decision. Even though some evergreen deciduous trees and shrubs are able to survive the harsher and longer winters, native species ultimately outcompete them.

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    They mostly exist as ornamental plants in a garden.

  • Can Frogs Really Predict the Weather?

    Can Frogs Really Predict the Weather?

    Frogs are weather experts. Some frogs and toads, based on their croaking, egg-laying, and even skin color, are said to allow us to predict whether it will rain soon or not. But what is the truth behind the frogs’ purportedly preternatural weather forecasting abilities?

    Long ago in Switzerland, if you would put a tree frog in a jar half full of water and give it a little ladder to climb, it could forecast good weather by climbing the ladder and bad weather by descending back into the water. Even today, in Germany, a weatherman is referred to as a Wetterfrosch, which translates as “weather frog.”

    Tree frogs are known to climb trees in favorable weather and make an awful noise, croaking sweetly for hours on end, thus the frog weather prediction theory actually has some validity.

    Monitoring the Humidity

    Numerous accounts point out the daily behavioral changes in amphibians and some reptiles related to predicted weather. Some species, for instance, become more active just before it starts to rain, while others are more likely to make their distinctive croaking sounds. The weather probably has a lot to do with this shift in behavior.

    Frogs and toads are highly reliant on accurately monitoring the humidity or temperature of their surroundings. That’s because amphibians are ectothermic, meaning they don’t produce their own heat. So, their blood, muscles, and skin, along with the rest of their organs, are always at the same temperature as their surroundings.

    Exceptionally Sensitive to Moisture Levels

    Frogs’ skin is very porous because of the abundance of glands on its surface. Because of this, they suffer significant water loss due to evaporation. But frogs and toads have a more refined sense of moisture via their skin than people do. In the tropics, for example, certain frog species usually come out of the underbrush when the humidity rises in anticipation of rain.

    Finally, amphibians like frogs and toads produce their offspring in aquatic environments. Thus, in order to effectively reproduce, they have to predict when there will be adequate puddles and pools from rain in which their tadpoles may grow. This means that when the weather or temperature changes, frogs have to adjust their behavior accordingly.

    Climbing Tree Frog

    So why then do frogs choose to remain low when bad weather is approaching, yet climb up when conditions are favorable? There are no precise investigations of the topic available. However, there are two theories among frog scientists as to why this occurs: The tree frog, in contrast to most other frog species, enjoys vertical environments and bright sunlight. Male frogs, especially those still in their juvenile stages, spend most of the late summer sitting on bushy branches and leaves to soak up some rays.

    However, the accessibility of food is equally important. The same goes for tree frogs, who also utilize their perches to swoop down on prey. Insects like mosquitoes are sensitive to weather changes, something our ancestors accounted for in their agricultural guidelines. With less wind and more sunshine, insects may ride the warm updrafts to greater heights in their flights. They tend to linger on the ground if a severe wind and a drop in temperature are expected.

    It is unknown, however, whether tree frogs actively pursue prey higher or lower, or if they instead respond immediately to changes in the weather. One thing scientists can agree on is that frogs and toads frequently respond to a shift in the weather before humans do. And this, of course, has nothing to do with clairvoyance.

  • How does drought change the soil?

    How does drought change the soil?

    How does drought affect the soil? Drought is a lack of water that occurs as a result of lower precipitation or higher evaporation. More evaporation occurs due to high temperatures, but also due to wind. A meteorological drought means that it is one to two months drier than usual. Even long after a drought is over and the soil has long since become waterlogged again, scientists can still tell that it has been exposed to drought.

    This was recently shown by an experiment. Researchers created extreme drought in a greenhouse for a meadow. The bacteria active in the soil did not like it at all: their number decreased and they were less active overall. This is a disadvantage for the soil because the bacteria are important for nitrogen fixation and ensuring the soil breathes. The fungi in the soil, on the other hand, benefited from the drought.

    Even two months after the end of the artificially induced drought, the original biological state had not been regained: soil bacteria had not recovered in terms of numbers or activity. Plants in the greenhouse also changed. Fast-growing grass species tolerated the lack of water better and spread more than slow-growing grasses. The experiment showed that droughts have a lasting impact on the soil habitat.

    How do plants react to dry soil?

    If the soil is too dry, this can have serious consequences for plants. When the roots of a plant realize that there is a lack of water, they send out a kind of alarm signal: a stress hormone is released that causes the stomata, the small pores in the leaves, to close.

    Stomata are important for photosynthesis, in which the plant converts carbon dioxide and water into oxygen and glucose. Carbon dioxide enters the leaf through them, and oxygen and water exit.

    A plant can prevent about 90% of water loss in soil

    However, when a plant suffers from drought stress, it tries to keep the water with it and therefore closes its stomata. This prevents about 90% of the water loss. Exactly how much varies from plant to plant.

    However, if the stomata are closed due to drought, photosynthesis no longer takes place, and so the plant does not grow. There may be fewer flowers or no flowers at all. Or there may be less or nothing left to harvest because grains, fruits, or vegetables cannot ripen properly. The taste of fruits and vegetables may also deteriorate.

    The drought stress on plants can be more clearly visible on fruit and vegetable shelves in summer: tomatoes, apples, and carrots can remain significantly smaller than in times when there is sufficient water.

    In extreme cases, a plant can die

    Drought is bad for farmers and consumers, but the situation is not yet existential for the plant itself. It only becomes so when the stomata do not close sufficiently. If water is still missing, the plant’s tissue collapses because the internal pressure is no longer there. It’s like a trampoline in that its fabric doesn’t have enough stretch. The plant wilts and there is a risk that it will die.

    But too little water not only makes plants thirsty but also starves them. An international research team evaluated studies in which 26 different tree species were exposed to drought stress experiments. Although carbohydrates and other nutrients were available, the trees starved. Without water, the nutrients could no longer be transported into the trees.

    How do animals in the soil react to drought?

    Not all animals are equally sensitive to heat and drought. Earthworms, for example, have no problem with drought. Their comfort temperature is between 50 and 60 degrees Fahrenheit (10 and 15 degrees Celsius). If the soil gets too warm and too dry, they simply burrow deeper into the earth. In extreme cases, they even curl up into a ball and hold a kind of summer sleep. Earthworms can survive dry periods well with this strategy – but then they become out of sight for other animals. For example, for the mole.

    Moles have a hard time with the drought

    The mole specializes in earthworms but they live one or two stories higher than earthworms during droughts. This is because moles dig a widely branching system of tunnels underground, but this only reaches down to a depth of about 3.3 feet (1 meter). Another problem for moles is their highly developed metabolism: they need around 1.8 ounces (50 g) of food a day and they need something to eat almost all the time, otherwise, they quickly starve to death.

    Digging new, deeper burrows only works to a limited extent in dry conditions. Instead, they search for food on the surface. But this is risky for the moles since they are then more easily become prays.

    Can a lot of rain at once save the soil from drought?

    Not necessarily. It may sound strange, but puddles or flooded areas are not an indication that the soil is sufficiently waterlogged. That’s because even if water is collecting on the surface, the soil may be very dry and in desperate need of water.

    Heavy rain is no use

    This happens especially when it rains a lot within a short time, for example, during heavy rain. Soil cannot absorb such a quantity of water so quickly, especially if it is very dry.

    This is because the so-called hydraulic conductivity of soil changes which means if the soil is dry, it takes longer for the water to seep through than if the soil is moist.

    Like baking in the kitchen

    The phenomenon also occurs in the kitchen when baking: An already liquid cake batter can be mixed with water relatively easily and turned into a mass. However, this is hardly possible if there is only flour in a bowl.

    If you dump water or milk onto this dust dry powder, a pool forms on the flour. The liquid does not seep into the flour properly and the flour remains mostly dry. It is the same with dry soil: it takes time for the water to seep through – the drier the soil, the longer.

    The water gets into the environment

    This means that heavy rain, i.e. a lot of rain in a short time, does not benefit the soil at all. The water does not seep into the ground, but gets into the environment: into streams, rivers, the sewage system, or cellars – a large part also evaporates.

    Since the soil does not benefit from heavy rain, hardly any water reaches the plants or trees rooted in it and the drought persists. That’s why rain doesn’t automatically reduce the risk of forest fires.

    What kind of rain regenerates the soil?

    Dry soil can best store the missing water if it is available evenly for a long time. Meaning: when it rains moderately. Not for hours, but rather for days, or even for weeks in the case of very dry soil.

    This is the rain British people are most familiar with which causes many people to be in a bad mood. However, nature is helped immensely by this long-lasting rain because the water can seep into the soil very slowly over a long period and neither runs off nor evaporates. Light, continuous rain ensures that the water seeps exactly where it is needed.

    How long does it take for soil to store enough water?

    Soils are generally rather poor at absorbing water. Water is slow to infiltrate. Generally, heavy soil takes more time to recover than light soil when it comes to droughts.

    Heavy and therefore good soil contains a lot of clay and thus, stores water optimally. However, it takes a relatively long time to absorb water. Soil can only manage about 0.2 inches (5 mm) of water per hour of rain.

    Lighter, sandy soils dry out faster, but also absorb water more easily. 0.8 to 1.2 inches (2 to 3 cm) of rainwater can seep into the soil in an hour.

    It can take months for the soil to recover from drought

    If summer is very dry, it takes months for the soil to recover from a drought. Even if the top layer, the topsoil, stores water again, it still takes a long time for the water to seep through to the deeper soil layers. This is because the main precipitation does not fall until winter, and the soil only slowly becomes full again.

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