88 The Poetry of Physics and The Physics of Poetry
radiation. This is why a greenhouse is many degrees warmer than the
outside air temperature even in the winter.
With the increase of CO 2 emissions into the atmosphere due to human
activity the overwhelming majority of scientists, especially climatologist,
believe that the current round of global warming is due to the greenhouse
effect. Ice core data over the past 800,000 years have revealed that the
amount of CO 2 has varied from values as low as 180 parts per million
(ppm) to the pre-industrial level of 270 ppm. Recent measurements of
carbon dioxide reveal that concentrations have increased approximately
from 313 ppm in 1960 to 383 ppm in 2009. This is why it is believed that
the dramatic increase in carbon dioxide levels is responsible for global
warming. It is why we now measure our carbon footprint and are trying
to reduce our emission of CO 2 into the atmosphere. As the planet warms
and more ice melts the albedo effects is reduced and the CO 2 and
methane gases frozen in the ice are released. Not only that but as the
oceans heat up they release their CO 2 content. Also as the surface area
of open water increases there will be more water vapour in the air and
water vapour is another greenhouse gas as it is a good absorber of
infrared radiation. These effects will only accelerate global warming,
which is why we have to take this challenge seriously. There is the
danger of a run away greenhouse effect whereby all the ice caps melt, the
temperature of the oceans increase dramatically and the warming of the
planet accelerates to the point of no return.