 |
|
||||
 |
 |
||||
|
|||||
| Deconstructing Global Warming |
 Before
we discuss global warming, we must first understand the concepts
of "Greenhouse effect" and "Climate change"
as well as their relationships with global warming. |
| Climate Change |
| The heat at the earth's surface comes from the sun. As the earth's orbit around the sun varies, and there are changes to its own rotation, the amount and distribution of heat energy received likewise vary. Hence, the climate changes. In addition, massive or frequent volcanic eruptions can also lead to climate change. Huge amounts of ash released in such eruptions can stay in the atmosphere for long periods, reducing the heat energy reaching the earth's surface, and so causing the temperature to decline. Yet
recent human activities have also resulted in changes to the climate.
The United Nations Framework Convention on Climate Change (UNFCCC),
defines "climate change" caused by human activities as
"a change of climate which is attributed directly or indirectly
to human activity that alters the composition of the global atmosphere
and which is in addition to natural climate variability observed
over comparable time periods". Although it is difficult to
estimate the extents to which the climate is changing because of
natural forces or human factors, it is beyond doubt that humans
are changing the earth's climate! |
| Greenhouse Effect |
|
According to information from the Intergovernmental Panel on Climate Change (IPCC), during the 20th century the earth's average surface temperature increased by 0.6°C. The IPCC reported it was clear indicated that the climate change was directly related to human activities. Massive burning of fossil fuels has pumped carbon dioxide and other greenhouse gases into the atmosphere. Over-logging has greatly reduced the area of forests, slowing the absorption of carbon dioxide from the atmosphere and exacerbating the greenhouse effect.
|
| The significance of stabilizing the climate |
The growth, activities and reproduction of all species depend on a stable climate. As the temperature rises, species of cold regions cannot quickly adapt to a warmer environment. Altering the population and distribution of a single species can affect all species in the food web. Climate change alters the water cycle. When temperatures rise, more water evaporates, and global precipitation patterns are modified, causing more rainfall in certain places on earth, while bringing drought to other parts of the world. Not only are drinking water supplies affected; so too are the distribution and production of vegetation and food crops. Moreover, some tropical diseases are likely to spread to colder regions when the climate warms. Therefore, global warming can extend the influence of certain diseases, which jeopardize humans and other species. In addition, if the climate continues to heat up, people will spend more time and hence energy on air-conditioning, adding extra pressure on the limited supplies of world energy. It is obvious that a suitable and stable climate is essential for the survival of all species, as well as the healthy and sustainable development of human society. |
| Climate change experienced in Hong Kong |
Even
tiny Hong Kong cannot escape global warming. From 1989 to 2007,
average temperature in Hong Kong increased more rapidly, at a rate
of 0.34°C per decade. In July 2007, the Hong Kong Observatory
even issued a record-breaking 12-days' Very Hot Weather warning.
In
addition to temperature increases, Hong Kong's sea level has also
risen. From 1954 to 2007, sea level in Victoria Harbour has increased
by around 0.13 m, an average of 2.4 mm per year. All these figures
are warning us: global warming is affecting Hong Kong. |
