Warming:
Fact or Fiction? The climate of the earth is indeed warming, with an increase of approximately 1 – 1½ degrees Fahrenheit in the past century. The warming has taken place as averaged globally and annually; significant regional and seasonal variations exist. The amount of warming aloft has been more difficult to quantify, but new research suggests a trend similar to that at the surface. Impacts can already be seen, especially in places like Alaska - where melting of glaciers and the retreat of Arctic sea ice have increased the vulnerability of local populations to effects such as coastal erosion. Human Influence Determining to what extent the current warming is due to human activity is complicated because large and sometimes sudden climate changes have occurred throughout our planet's history - most of them before humans could possibly have been a factor. Furthermore, the sun/atmosphere/land/ocean "climate system" is extraordinarily complex. For these reasons it cannot be conclusively stated that humans are completely responsible for global warming. |
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Computer model simulations and other assessments of the rate of global warming and the amount of increased greenhouse gases provide strong evidence that a significant portion of the current warming is a result of human activities.
Humans are also changing the climate on a more localized level. The replacement of vegetation by buildings and roads is causing temperature increases through what's known as the urban heat island effect. In addition, land use changes are affecting impacts from weather phenomena. For example, urbanization and deforestation can cause an increased tendency for flash floods and mudslides from heavy rain.
The Impact on European Weather
Despite an increase in average global temperatures, parts of Europe and to a lesser extent eastern coast of North America could experience a cooling trend as a result of global warming. Europe's climate is largely controlled by the warm North Atlantic current, or the Gulf Stream, keeping western European winter’s much milder than it would otherwise be.
Evidence suggests
that with an overall rise in temperatures, an increase in rain and snow
in the area as well as melting of snow and ice from Greenland and the
Arctic Sea could be linked with a decrease in European temperatures. If
enough freshwater is added to the North Atlantic from Greenland and the
Arctic Sea, it would likely disrupt the flow of the North Atlantic drift
by reducing the density of the surface water and thereby weakening or
cutting off the flow altogether. Consequently, temperatures in parts of
western Europe would plunge drastically without the poleward flow of warm
ocean water, causing severe agricultural and world-wide implications.
The Future
There is uncertainty in forecasting both the amount of warming and magnitude
of resultant specific impacts. Potential outcomes during the next century
and beyond range from moderate and manageable to extreme and catastrophic,
depending on a number of factors including location and type of effect.
A better understanding of the climate system is vital, as are improved
observations of that system and further advancements in the computer models
used to help forecast the future state of our climate. However, the rate
of climate change could exceed the pace at which scientists can provide
irrefutable answers.
Variability is an ever-present part of our climate regardless of cause,
and therefore the ability to adapt to any changes that do occur is crucial.
Copyright
The Weather Channel 2003
Emily Powell, meteorologist at WSI Europe, contributed to this report.