Branches of international environmental law - Introduction to International Environmental Law - page 150

International Watercourses, 14 which was adopted in 1997. Its rules are more
detailed and more ambitious, which is probably why it has not yet come into
force. Among other measures, it establishes another principle beside the prin-
ciple of equity in the realm of international watercourses: a state shall not
cause signifi cant damage to another watercourse state. To secure this, the
convention also provides for communication procedures between the states
in order to avoid signifi cant transboundary environmental impacts. Part IV of
the convention regulates the ecosystem approach to the entire watercourses.
Rivers, lakes and groundwater are today understood to be an intricate
drainage basin: a hydrological unit that also includes the groundwater in
connection with the surface waters. In 2008, the UN International Law
Commission completed its own draft articles on the Law of Transboundary
Aquifers, 15 groundwaters that are not connected with surface waters and can
be compared with such legally shared natural resources as transboundary oil
and gas wells.
Conservation of biological diversity
Biological diversity is the outcome of 4.5 billion years of evolution. The vari-
ety of life has grown more versatile as natural selection has removed the less
successful mutations from the genetic stock, while the more successful ones
have gradually accumulated. New species specialize and conquer their ecolog-
ical position; this process can cause the natural extinction of another species.
Scientifi c research has also discovered that since the origination of multi-
cellular organisms, approximately fi ve great waves of extinction have taken
place after natural catastrophes.
Scientists now believe that we are at the threshold of the fi rst wave of
extinction caused by man. It is estimated that there are about 12 million
species, of which only 1.4 million have been scientifi cally surveyed. Since our
actions are resulting in the death of species all the time, we are probably
destroying species that were previously unknown. The main reasons why
species are dying out are the rapid increase in human population and the
changes in the lifestyles of human communities, made possible by economic
growth and technological progress.
The depletion of biological diversity is a serious problem: 4.5 billion years
of evolution have resulted in a set of species that have, during their histories,
adapted to life in highly diverse environments. If some of them perish, we will
be less adaptable to the constantly changing conditions on our planet, so long
as our actions continue to change conditions at an accelerating rate.
The history of the conservation of biological diversity
In the twentieth century, the international community did little to promote
the diversity of species or habitats. After the Second World War, conservation
agreements were mainly aimed at protecting big animals, the so-called 'charismatic