Part. I
TROPICAL FORESTS
It took millions of years of growth to create these diverse and complex green jungles. They once covered 15 percent of the earth’s land surface, but today only 6 percent remain – even though they are home to more than 50 percent of all plant and animal species on earth.
In the last 50 years wildlife populations have disappeared by 60 percent. Animals such as tigers, dolphins, orangutans, rhinos are threatened and many other animal and plant species are losing their habitat and lives. It is estimated that 28 percent of all species are at risk of disappearing.
From South America over Central Africa to Southeast Asia rainforests are chopped and burnt down at an extensive rate in recent years. Around 8 million hectares of forests are destroyed every year. That is an area equivalent to 27 football fields every minute. Yet tropical forests interact with the atmosphere and exchange vast amounts of water and energy with it, and thus play an important role in responding to climate change. By deforestation, we eliminate plants that would otherwise take carbon out of the atmosphere as they grow.
A majority of the deforested area, at least 65 percent are transformed into agricultural land for animal husbandries and the cultivation of soybeans. The production of soybeans are mainly needed for animal feeds. Apart from that, the livestock sector is responsible for 15 percent of global emissions, 20 percent of land degradation through overgrazing and around 30 percent of the freshwater footprint. In addition, ruminant animals emit methane as they digest grasses and plants. This is another contributor to climate change since methane is a many times more potent greenhouse gas compared to carbon dioxide.
Reforestation is good, but leaving old trees standing is more effective, because of their higher capacity to absorb carbon dioxide. Healthy ecosystems provide essential goods and services, and the loss of only one key species can impact a whole ecosystem and eradicate its potential to fulfil valuable ecosystem services.
Part. II
Coral reefs are often called the tropical forests of the sea, because of their high density of species.
TROPICAL CORAL REEFS
Corals are over 500 million years old – much older than the dinosaurs – but in the past two decades they have experienced various global mass bleaching events in which reefs around the world have suffered great losses all triggered by anthropogenically induced climate change.
There are many different species of corals with all sorts of colourful structures, patterns and shapes. They create hugely diverse and complex cities for fish and other marine life. Corals cover less than one percent of the ocean, but are home to 25 percent of all marine species.
Corals look more like plants or rocks, but they are animals and have a really unique relationship with another species, that actually lives inside of them. When corals met algae around 210 million years ago it became clear, that the symbiosis between these two very different organisms is the basis for a healthy reef ecosystem. Changes in ocean chemistry and temperature can have extensive effects on corals and with that a wide range of other marine organisms. But corals in particular are extremely sensitive to pollution and rapid environmental changes and only thrive under specific conditions.
The bleaching is a stress response in which the unicellular algae abandon the tissue of its host, hence leaving the coral without its distinct coloration. Half of the world’s largest coral reef system has already fallen victim to this phenomenon. Based on our current lifestyle, the rest of the corals could be gone within the next 30 years. If corals erode faster than they can rebuild – and they unfortunately grow relatively slowly – entire species would disappear. Also corals make up reefs which serve as natural protection from storm surges that could otherwise cause disastrous floods impacting coastal communities. Losing such an essential part of the ocean environment could therefore have rippling effects that cause much broader collapses.
GREAT LOSS OF SPECIES
In earth’s history, mass extinctions have been caused by catastrophic events like volcanic eruptions or the impact of meteors on earth. Five mass extinctions have happened in the last 500 million years, although there is no detectable pattern in their particular timing, the last one occurred in a geologically short period of time.
It is estimated that the current extinction rates are hundreds of times faster than they would be if humans were not around. We amplify the species loss with global climate change, deforestation, mining, pollution, poaching and wildlife trade as well as agriculture. The pace of extinction has accelerated to the point that species are vanishing before we even have a chance to discover them.