Unbearable heatwaves are torture for both humans and wildlife

Unfortunately, summer of 2019 in Northern Europe has started the same as 2018 – with dry and hot weather. Even though heatwaves do not surprise most of the people, both humans and wildlife are struggling to survive during these enormously hot periods. Since heatwaves are more and more common in the regions up to north, there are more discussions about the role of global warming in their formation. My beloved home country Lithuania (as well as other Baltic sea region countries) according to “GreenMatch” evaluation was affected by global warming the most from all European Union members.

What is a heatwave?

Heatwave is a period of unusually hot weather when temperatures are enormously higher than relatively normal to the season. Heatwave can cause an increase in precipitation or on a contrary prolonged period of drought depending on a region and humidity of high-pressure stall. Why should we care about these heatwaves? Neither infrastructure nor native species of flora and fauna are adapted to such a long period of heat. As a result, infrastructure such as roads, buildings can be damaged and health of both animals and humans getting at risk. Even though that +30 degrees Celsius is a normal temperature for residents of California, it does not mean that its comfortable for residents of Northern Finland. Just as humans living in northern latitude neither have ever invested in air cooling systems nor ever adapted to experience prolonged exposure to heat and sun, wild flora and fauna does not have any adaptations to survive such a period either.

Heatwaves causes not only droughts but formations of severe storms, increases risk of forest fire and harms both human health and environment.

How heatwaves affect animals?

Both physical and behavioural features of wild animals depending on habitat where generations of their ancestors adapted to live in. Especially those species which thrives in middle and higher latitudes, are know for quite high tolerance of temperature and precipitation range because of the changing seasons. However, when the temperatures rise too much and animals are exposed to much higher than normal heat for prolonged time, there is a problem. Most of these animals do not have such a great behavioral and physical adaptations to survive heat as temperate and tropical species. As a result, neither they know how to behave during the day to avoid heat nor they metabolism is efficient enough to survive heatwaves.

Blue Tit (Cyanistes caeruleus) common species in Northern Europe
Blue Tit (Cyanistes caeruleus)

During recent years scientists in Sweden made an experiment with blue tits (Cyanistes caeruleus) which is common species in whole Northern Europe. They decided to check how they are succeeding to feed their young during heatwaves. One control group was a common blue tits and other group of tits were shaved (some of the feathers were removed) in order to improve they ability to cool off during heatwave which leads to better adaptations to move and feed during that time. After the experiment scientist noticed that younglings of shaved tits had higher body weight and were larger that control group. On a contrary, control group younglings were much weaker.  As a result, it proves that heatwaves can reduce survivability of local fauna because of lack of adaptations.

There are reports about both human and livestock (cattle, poultry, rabbits etc.) casualties during the heatwaves. However, humans and livestock are getting care, water and food. Wildlife fauna needs to survive on its own and their losses due to heatwave is not counted. What is more, high temperatures increase rates of decomposition enormously so basically, we do not see any remains in the wild.

What happens with plants during heatwave?

Plants are usually forgot while talking about heatwaves. Most of us only cares about lawn in the yard, however heatwaves are challenging for all forms of life including plants. Just as you are forced go to the hospital if your body temperature reaches 40 degrees Celsius, plants biochemical reactions inside their cells stops at rising temperature. As a result, both photosynthesis and metabolism reactions discontinue. What is more, most of the northern plant species closes their stamina to prevent water loss due to evaporation.

Intensity of photosynthesis of European beech and Norway spruce in different temperatures
Intensity of photosynthesis of European beech and Norway spruce in different temperatures.

Norway spruce (Pice abies) is a common species in whole higher latitudes of northern hemisphere. However, if it is affected by higher levels of solar radiation – photosynthesis intensity in its spikes decreases. Photosynthesis of spruce reaches its maximum when temperature reaches 35 degrees of Celsius and continuous to decrease if temperature rises.  Its an important detail that photosynthesis effectiveness is measured in optimal humidity and heatwaves usually causing negative effects as enormous droughts or prolonged precipitation periods. If temperature reaches 40 degrees, photosynthesis simply stops, and plant is no longer able to produce nutritional matter for its needs.

On a contrary, European beech (Fagus sylvatica) which is growing in lower latitudes in Central and Southern Eurasia, reaches its photosynthesis peak around 37 degrees and is still able so synthesise organic matter at 45 degrees Celsius. After extremely hot summer of 2018 huge areas of Norway spruce are suffering from the pests, deceases and damaged root system. Due to inefficiency of nutrition and water, plants had become less resistant for environmental and biological factors.

Huge areas of spruce are drying out and are damaged by pests and environmental conditions.
Huge areas of spruce are drying out and are damaged by pests and environmental conditions.

Do heatwaves affect underwater life?

Water turns green during prolonged periods of heatwave as a result of algae blooming.
Water turns green during prolonged periods of heatwave as a result of algae blooming.

Heatwaves are the one of the major threats for marine biodiversity. Both carbon dioxide and oxygen are crucial for marine life. Carbon dioxide is necessary for photosynthesis (plants and algae are) and oxygen in crucial for breathing (almost all organisms do that). However, all gasses (both CO2 and O2 are gas) concentration in water is decreasing when temperature is rising. As a result, when there is no or very low concentration of these gasses, most of living creatures cannot survive. As a result, in these oxygen or carbon dioxide depletion zones biodiversity critically decreases. A lot of biologist around the world are reporting process called coral bleaching when corals turn white. This is happening because of depletion of oxygen and carbon dioxide, why algae which live inside corals dies. Even more detrimental effects can be seen in inland water-bodies – because of decreasing water level coast plants are wilting and higher temperature accelerates processes eutrophication such as toxic water blooming.

How you can help?

During the heatwave most of land animals are suffering from lack of water. It is becoming more challenging to find it. You can help them with making drinking spots for birds, mammals and insects. Please note, that birds water fountains should be hard to reach for predators as cats. Mammals water bowls should be placed low – imagine the size of a hedgehog. Insects love dripping water or very shallow water bowls.

Make sure you yard has some shadowing. If there is basically none, put some boxes or other stuff to make a refuge from sun for local cats and other small fauna.

Avoid watering plants during the hottest hours from 12 to 16 because water heated by sun can cause damage for their leaves. Also please find out what is the state of water resources in your area if depletion of is appears, please save as much water as possible and avoid unnecessary use of it.

Hedgehogs also struggling to find water sources during heatwaves.
Hedgehogs also struggling to find water sources during heatwaves.
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