ECOLOGY BASICS III - Pre-Intermediate

							ECOLOGY BASICS III
     Vocabulary: Useful terms
    Complete the terms in the left column by adding a word from the right
column, some terms can combine with more than one word, some words from the
right column can be used more than once.

                    acid
                  nuclear                               effect
                     sea                                energy
                 recycled                                fume
                  tropical                                fuels
                   public                           waste product
                    solar                                jams
                    noise                                  rain
                  exhaust                                layer
                   traffic                             changes
                    finite                             disasters
                renewable                              pollution
                   global                             rainforest
                  natural                             transport
                greenhouse                            resources
                   ozone                                gases
                      air                              warming
                   clean




      Reading: THE     GAIA HYPOTHESIS
What is the Gaia hypothesis? The idea is that we have discovered a living
organism, which is bigger, older and more complex than anything from our wildest
dreams. That organism is the Earth (or Gaia). The idea was introduced by James
Lovelock. In the 60’s, he worked for NASA on experiments which looked for life
on Mars.
       He analysed the atmosphere of Mars and he found out that the composition
of Mars’ atmosphere has not changed during its history. By contrast, the
composition of the Earth‘s atmosphere has changed, but it has still kept a
balance. Life first appeared on the Earth about 3,500 millions years ago. From
that time until now, the Earth’s climate has changed very little as the fossil fuels
show. But the heat from the sun, the properties of the earth, and the composition
of the atmosphere have changed during the same period. This probably means
that there must be some complex process, which has kept the atmosphere in
balance.
       The experiments found no life on Mars but Lovelock started to see the
Earth from a different perspective. He began to think that our planet is an
organism, a self-regulating system, a living being. He named that being Gaia (after
a Greek goddess). Gaia is not only the biosphere where living organisms exist. It is
also not only the biota – the collection of all individual living organisms.
       Gaia is also the rocks, the air and the oceans. Gaia has been influencing the
Earth since the origins of life, and it will influence it for as long as life on Earth
exists. For example, the Gaia hypothesis says that biota produces active
processes that keep the temperature, oxidation, acidity and other important
properties of the rocks and waters constant.
       Maybe it is hard for you to believe that the Earth is alive. But many atoms
in the rocks down in the magma were part of the life of which we have all come
from.

       Comprehension:

Who introduced the hypothesis?
How did it happen?
Explain the main principles of the hypothesis.


       Discussion: Read the text and discuss it.

ARGUMENTS FOR AND AGAINST THE GAIA HYPOTHESIS
+ The Earth’s original atmosphere had no oxygen. The beginning of photosynthesis
2.5 billion years ago started to produce oxygen which was released into the
atmosphere (presently 21%). Geological research shows that the amount of
oxygen on the Earth has been the same for the past billion years.
+ If the amount of oxygen in the atmosphere was 35%, the planet would burn up.
Why has the amount of oxygen stayed the same, i.e. below the dangerous levels?
Why did the amount of oxygen build up from 0 to 21%, and then stop? One
possible answer is the biological production of methane by bacteria. Methane has
stabilised oxygen concentrations, because it combines with oxygen to produce
CO.
 + We know that climate has changed in the past, but the change was not
extreme. Although the output from the sun has changed greatly, the earth’s
temperature has not changed very much. One of the reasons why our planet has
not burned up is the production of plankton, because it removes CO from the
atmosphere.

- Oxygen was first produced more than 3 billions years ago. But it took 2 billion years
before it built up in the atmosphere. Why did it take so long? And when it finally was
built up, it was a poison for the then-existing life, which had to move to anaerobic
environments. So oxygen helped the evolution of aerobic life (because it developed the
ozone layer), but it killed a part of the major life forms 2 billions years ago.
- Gaia cannot reproduce herself, so it cannot be alive.
- The theory is not scientific, because it cannot be proved by a controlled experiment.
- Some scientists say that organisms cannot produce global action, because it is not in
their genetic code.