How Climate Change Affects Biodiversity, Part Two

 

Coral bleaching

Coral are marine organisms. Dead and living coral skeletons make up coral reefs like the one found in Watamu or in the Great Barrier Reef in Australia. When people talk of coral they assume it is one creature but it is made up of organisms called polyps and algae. In real sense, coral tissue is clear but the algae have various shades of photosynthetic pigments. Thus there are many species of differently coloured coral. It’s a symbiotic relationship where the coral provide anchors and give a constant supply of carbon dioxide while the algae carries out photosynthesis , provides food for the coral and aids in calcification.

some of the marine life at the Watamu coral reef - such is now under threat from climate change

Coral reefs form the habitat for a very diverse and huge number of marine organisms.  Coral is also very sensitive to temperature changes. Coral lives in the upper layers of the ocean where sunlight permeates and the temperature is influenced by the atmosphere though the waters are a bit shaded. 

 What global warming does is to cause atmospheric and hence ocean temperatures to rise. The warmer waters then affect the ability of algae to manufacture food which then causes coral to expunge the algae. Without their source of food, coral dies and become white. This whitening is called coral bleaching.

Ocean acidification is a phenomenon resulting from oceans absorbing carbon dioxide from the atmosphere more than they normally do. Now, in nature, oceans act as carbon sinks alongside forests. But what happens is that as more carbon dioxide is emitted then more of it is absorbed by the oceans. According to the chemistry classes I remember, water plus carbon dioxide results in carbonic acid which lowers ocean pH. Low ocean pH interferes with the ability of marine organisms to uptake calcium to maybe form calcium shells. They die.

Ocean acidification is another effect of the 'high carbon pathway of development' which results mainly from use of fossil fuels.

Ocean stratification is whereby warm nutrient poor water sits on colder but nutrient rich water. The laws of chemistry dictate that less dense substances float on denser ones. High temperature causes a substance to expand and thus reduces its density. Global warming does this to oceans. Now there are organisms called phytoplankton. They form the basis of food chains in the ocean. They depend on ocean mixing and so will die or become extinct because they don’t get enough nutrients, oxygen and balance in water temperature. If phytoplankton die, the domino effect is that everything else dependent on it dies too. That water zone becomes a dead zone. So you see, human induced climate change will affect all the species present on Earth with a good number becoming endangered or extinct.

The Arctic is warming up twice as fast as the rest of the planet. Even more than the Antarctic. Why? Because as ice melts in the Arctic, it uncovers dark spots in land and water. Simple chemistry taught us that dark colours absorb light and heat while light colours reflect them. So the more the Arctic melts, the more it warms up. Now this is both a cause and effect on climate change. It is an effect of climate change because global warming causes the ice sheets to melt, adding water into the oceans leading to various dangerous consequences for different flora and fauna.

It is a cause of further climate change because part of the planet’s ability to reflect solar radiation back into space comes from these ice sheets. So the more they vanish, the more sunlight is retained and thus the more the global warming.

Also, as global warming causes the Arctic to melt, permafrost (frozen subsoil) thaws and the methane that was trapped is released into the atmosphere thus worsening climate change.

What does this mean for Arctic flora and fauna? Polar bears, seals? Animals such as polar bears depend on ice sheets to move around which in turn influences how they get mates or homes. Their main diet is fish and this would be affected if the ice sheets disappear. What has not been extensively studied is the impact of warmer oceans on marine organisms.

The Antarctic is also affected but to a lesser scale as compared to the Arctic. Scientists have theorized that it is because weather systems in the Antarctic are relatively stable, the ice sheets are much thicker and there is the ozone cooling effect. All this makes the atmosphere over South Pole colder. However slight changes have been observed with cracks observed on ice sheets, permafrost thawing and water locked up in ice being released. This in turn affects animals like penguins which depend on the Antarctic for breeding.

mangroves on the Kenyan coast - courtesy of cordioea

Mangroves are a tree species which grow in the confluence between ocean and river waters. They are found in brackish waters which are found at the mouth of rivers. Because the ground is waterlogged, they rely on aerial roots which aid in breathing. By their very nature, mangroves offer a habitat for and are part of a diverse and rich ecosystem such as rare butterflies, turtles and waders (birds). They also act as a buffer to protect land further inwards from dangerous waves. Now, as mentioned earlier, mangroves need a balance between sea and fresh waters. But with climate change, there are rising sea levels which mean that seawater invades more and more continental land. Sea water is saline by nature and so the more it advances, the lesser the acreage of mangrove forests will be. Rising sea levels will also eventually submerge this unique species. By the way, did you know scientists have discovered that mangroves absorb five times more carbon dioxide than forests on land? Now you know.

As is typical of us human beings, we usually think of addressing such problems with a selfish viewpoint. How will all this affect mankind?

Tourism

Wildlife and marine tourism is a major economic sector for most countries an example being where coral or game parks are found. If this biodiversity is affected then jobs will be lost, livelihoods get affected, political and regime changes are likely to be put into effect by voters, this partly influenced by climate change. 

Destruction of water catchment areas by climate change related events will lead to water scarcity. This will be especially dire in desert areas which depend on certain waterways for survival. An example of such is Egypt which depends on the Nile whose source is Lake Victoria which in turn is fed by rivers originating from the Mau Escarpment which is under threat from both human – caused destruction and climate change, (this ladies and gentlemen is what we call a butterfly effect, how one small action in one place can cause huge repercussions in another far off area)

Impact on human health

A lot of the medicine that is used on Earth is from rainforests. So we destroy forests through climate change, we help pathogens kill us.

Some viruses and bacteria could also jump from animals to humans.

But now to more altruistic reasons,

Loss of biodiversity

Loss of coral causes a ripple effect. Some species lose food, other lose habitat, some adapt, some migrate, others would become extinct.

Another example is that gorillas already under threat from poaching and loss of habitat due to human activities would further lose out if their habitat is negatively affected by climate change.

Loss of scientific gene banks

A good number of species remain undiscovered especially in the deep oceans and rainforests. But if the entire food chain that starts with phytoplankton is negatively affected, then we will never discover new species and entire scientific wonders.

The same applies to undiscovered species in the rainforests. Rainforests contain 50% of all known species.

Loss of heritage

Future generations will never get to see the wonders and the richness and diversity of planet earth as it is right now

Loss of habitat and cultural diversity

This would apply to tribes that live in the Amazon and the pygmies who live in the Congo rainforests. If their natural homes are lost then so will much of their culture and heritage.

Finally,

We are further destroying or reducing biodiversity by cutting down trees, flooding forests to create hydroelectric dams or drilling for oil in rainforests. So if your city or town participates in this, stop them.