Information on the early Earth and its evolution can be
found on the links below.
Earth is currently our only example of a habitable planet. Consequently, studying its long-term evolution is essential for understanding why the Earth became habitable and why terrestrial life has persisted for billions of years.
Earth's climate has
been influenced by the Sun,
which has gradually brightened by 25-30% in the last 4 billion years,
and by the presence of three major greenhouse gases, carbon dioxide (CO2),
water vapour (H2O), and methane (CH4) .
Methane was probably an important greenhouse gas during the first half
of Earth's history. The rise of atmospheric oxygen (O2)
around 2.4 billion years ago may have caused the collapse of the
methane greenhouse that triggered worldwide glaciation at that
time. In addition to altering the climate, the rise of O2
permitted the evolution of complex life and created a stratospheric
ozone layer that blocks out solar ultraviolet radiation [2,3].
influence of biology on the evolution of Earth's atmosphere could help
us find life on planets around other
stars. Oxygen, ozone, and
methane are only produced in simultaneous abundance by life.
These gases create absorption lines in the spectra of
light from planets around other stars that may allow us to
identify the presence of life.