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Loss of Biodiversity: Why are we losing so many species? Part IV

Why are we losing so much of our biodiversity?

To make sense of the specific reasons for the loss of biodiversity, this is one programme (“The State of the Planet”, part of BBC’s “Earth” DVD series) that hit the nail on the head. It’s always a pleasure to watch Sir David Attenborough, and of course get inspired by his passion and energy. I’ve only seen this increase over the last few decades as a sense of urgency comes into play, while he personally sees the deterioration in the state of the planet over his lifetime.

78% of oceans are being fished to the limit. 170,000 square kilometeres of rainforest are destroyed every year, nearly 200,000 square kilometeres of land are made desert every year. There is no doubt we are in the midst of a crisis of epic proportions. Why is this happening? According to Sir David, there are 5 main human activities that can be attributed to this biodiversity crisis.

1. Overharvesting- Every growing population coupled with more efficient technology makes harvesting quicker than ecosystems can reproduce and regenerate. Trees are being felled 10 times faster than they are being replaced by new growth ones. 70% of fish species are being harvested above the rate they can reproduce. It should not take long to understand if we continue at this rate, entire fish species will vanish and forests will disappear. Where will we go then?

2. Introduction of alien species-  This can often decimate populations of native animal species. For all the illusion of greenery in the island of Hawaii, it is impoverished in terms of the native species which have all but vanished. One example is the beautiful and exotic snail species which have disappeared due to introduction of rats, pigs, and West African killer snails.

3. Destruction of habits- Sir David talks of Cape Town, which is a biological hotspot with about 5,500 types of plants. This area is endangered as 40% of the area is destroyed by agriculture and the spread of the town. There are thousands of hotspots the world over. Orangutans and other species in Indonesia are endangered because of the rapid clearance of rainforests due to oil palm plantations. A similar fate awaits the mountain gorillas of East Africa.  Most of the IUCN list of endangered animals are those which are mainly affected by habitat loss.

4. Islandisation of habitats- With the spread of agriculture, urbanisation and deforestation, what inevitably happens is that undisturbed pockets of nature become islands. Even nature reserves are islands. Unique species may be localised to these islands, and even if they are located across islands, they may not be able to move between islands. If anything were to happen to these islands, for example due to further infringement, or drought, these species are very vulnerable to extinction.

5. Pollution – Humans are so dependent on air and water, and yet we indiscrimately use these precious resources like an open and free sewer, dumpling all effluents, emissions from industries. One kind of pollution, that of pumping carbon dioxide into the atmosphere, is causing severe changes in the earth’s temperature, leading to endangering of species from the polar bears to coral reefs.

Habitat destruction and climate change are key reasons for extinction of species, 20% all species is expected to disappear in just three decades. We may well lose over 2/3rds  of all life species in a century’s time.

Change is an intrinsic part of the natural cycle, but it is the unprecedented speed with which all these five factors are happening is leading to a historical rate of extinction, what is being called the 6th wave of extinction (which I’d talked about in the previous blog).

If we look at history, civilisations such as Easter Island, Indus valley, Great Zimbabwe and so on collapsed because they reached a point where the trees, water resources and other natural resources had all been over-exploited, leaving nothing for the humans to survive on. A similar fate awaits us, unless we learn to use our natural resources in a way that is sustainable.


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Posted by on Nov 26 2008. Filed under Biodiversity, Climate Change, Sustainable Growth/Development. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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