Asteroid Affirmative



Download 0.74 Mb.
Page39/66
Date conversion29.04.2016
Size0.74 Mb.
1   ...   35   36   37   38   39   40   41   42   ...   66

Biodiveristy ! – Extinction



Ecosystem collapse causes extinction

Jayawardena 9 (Asitha, London South Bank University, “We Are a Threat to All Life on Earth”, Indicator, 7-17, http://www.indicator.org.uk/?p=55)

Sloep and Van Dam-Mieras (1995) explain in detail why the natural environment is so important for life on Earth. It is from the environment that the living organisms of all species import the energy and raw material required for growth, development and reproduction. In almost all ecosystems plants, the most important primary producers, carry out photosynethesis, capturing sunlight and storing it as chemical energy. They absorb nutrients from their environment. When herbivores (i.e. plant-eating animals or organisms) eat these plants possessing chemical energy, matter and energy are transferred ‘one-level up.’ The same happens when predators (i.e. animals of a higher level) eat these herbivores or when predators of even higher levels eat these predators. Therefore, in ecosystems, food webs transfer energy and matter and various organisms play different roles in sustaining these transfers. Such transfers are possible due to the remarkable similarity in all organisms’ composition and major metabolic pathways. In fact all organisms except plants can potentially use each other as energy and nutrient sources; plants, however, depend on sunlight for energy. Sloep and Van Dam-Mieras (1995) further reveal two key principles governing the biosphere with respect to the transfer of energy and matter in ecosystems. Firstly, the energy flow in ecosystems from photosynthetic plants (generally speaking, autotrophs) to non-photosynthetic organisms (generally speaking, heterotrophs) is essentially linear. In each step part of energy is lost to the ecosystem as non-usable heat, limiting the number of transformation steps and thereby the number of levels in a food web. Secondly, unlike the energy flow, the matter flow in ecosystems is cyclic. For photosynthesis plants need carbon dioxide as well as minerals and sunlight. For the regeneration of carbon dioxide plants, the primary producers, depend on heterotrophs, who exhale carbon dioxide when breathing. Like carbon, many other elements such as nitrogen and sulphur flow in cyclic manner in ecosystems. However, it is photosynthesis, and in the final analysis, solar energy that powers the mineral cycles. Ecosystems are under threat and so are we. Although it seems that a continued energy supply from the sun together with the cyclical flow of matter can maintain the biosphere machinery running forever, we should not take things for granted, warn Sloep and Van Dam-Mieras (1995). And they explain why. Since the beginning of life on Earth some 3.5 billion years ago, organisms have evolved and continue to do so today in response to environmental changes. However, the overall picture of materials (re)cycling and linear energy transfer has always remained unchanged. We could therefore safely assume that this slowly evolving system will continue to exist for aeons to come if large scale infringements are not forced upon it, conclude Sloep and Van Dam-Mieras (1995). However, according to them, the present day infringements are large enough to upset the world’s ecosystems and, worse still, human activity is mainly responsible for these infringements. The rapidity of the human-induced changes is particularly undesirable. For example, the development of modern technology has taken place in a very short period of time when compared with evolutionary time scales – within decades or centuries rather than thousands or millions of years. Their observations and concerns are shared by a number of other scholars. Roling (2009) warns that human activity is capable of making the collapse of web of life on which both humans and non-human life forms depend for their existence. For Laszlo (1989: 34), in Maiteny and Parker (2002), modern human is ‘a serious threat to the future of humankind’. As Raven (2002) observes, many life-support systems are deteriorating rapidly and visibly. Elaborating on human-induced large scale infringements, Sloep and Van Dam-Mieras (1995) warn that they can significantly alter the current patterns of energy transfer and materials recycling, posing grave problems to the entire biosphere. And climate change is just one of them! Turning to a key source of this crisis, Sloep and Van Dam-Mieras (1995: 37) emphasise that, although we humans can mentally afford to step outside the biosphere, we are ‘animals among animals, organisms among organisms.’ Their perception on the place of humans in nature is resonated by several other scholars. For example, Maiteny (1999) stresses that we humans are part and parcel of the ecosphere. Hartmann (2001) observes that the modern stories (myths, beliefs and paradigms) that humans are not an integral part of nature but are separate from it are speeding our own demise. Funtowicz and Ravetz (2002), in Weaver and Jansen (2004: 7), criticise modern science’s model of human-nature relationship based on conquest and control of nature, and highlight a more desirable alternative of ‘respecting ecological limits, …. expecting surprises and adapting to these.

Biodiveristy ! – Extinction


Biodiversity is key to extending the lifespan of the human species

Evonobel 10 [http://actionbiodiversity.org/?p=20 ecological organization]

Biodiversity is important because all life human science is aware of depends on other life for its own survival. Every living entity, down to the lowest fungus, requires another species in order to survive. Even plants that derive the majority of their energy from the sun and soil rely on elements within the soil that are often drawn from the decomposition of other organisms. When species go extinct, and biodiversity is threatened as a result, other species whose well being depended on the now extinct groups are pushed towards the edge themselves. And for all the accomplishments human civilization has achieved, it is itself still wholly dependent on other lifeforms for its own sustenance. Humans eat plants and animals both, and their bodies cannot receive proper nourishment without consuming a wide variety of organic substances. It is in the interest of human civilization itself to conserve biodiversity even if it may mean constraints on continues economic growth. Conserving biodiversity is of the utmost importance in order to keep the ecosystem capable of sustaining life for the long term. With no other planet within reach that has near to the degree of biodiversity available on Earth, conserving biodiversity in all its various forms is vital to the continued survival of the human species. Not to mention that a world without wild creatures would be rather dull indeed.

Ignorance of the value of biodiversification leads to our demise as humans

Shah 9 ["Loss of Biodiversity and Extinctions." GlobalIssues.org. http://www.globalissues.org/article/171/loss-of-biodiversity-and-extinctions#LongTermCosts ]

Increasing demands of globalization and consumption have made a significant impact on biodiversity loss. Areas of high resource extraction are often the regions with the highest species density.  India is home to around 46,000 different species of plants alone, and has as many as 81,000 different species of animals, which accounts for approximately 8% of the world’s biodiversity. Brazil, whose Amazon region is subject to extreme deforestation, is home to 55,000 species of flora, accounting for 22% of the earth’s total.  This destructive activity in such high density areas plays a large role in our current rate of extinction. Various approaches have emphasized the protection for keystone species (organisms with exceptional effects on their environment, proportional to their biomass), endangered species, and areas known as biodiversity hot spots. These regions have especially high densities of biodiversity. The dangers of attempting to set priorities for preservation efforts are due to our ignorance of the value any particular species provides to the web of life, or the options value it might provide in a rapidly changing global environment.

1   ...   35   36   37   38   39   40   41   42   ...   66


The database is protected by copyright ©essaydocs.org 2016
send message

    Main page