Government of Canada Climate Change Web site
http://www.changementsclimatiques.gc.ca/english/index.shtml

Because of it's simplicity, this official canadian website is a perfect introduction for those who are not familiar yet with Climate Changes.

There are some basic questions such as :

• What is Climate Change ?
• How will it affect us ?
• What can we do about Climate Change ?
• What are we doing about Climate Change ?

The answers are clear too : "What is Climate Change : the science behind the story"

Climate change is a change in the "average weather" that a given region experiences. Average weather includes all the features we associate with the weather such as temperature, wind patterns and precipitation. When we speak of climate change on a global scale, we are referring to changes in the climate of the Earth as a whole. The rate and magnitude of global climate changes over the long term have many implications for natural ecosystems.

A natural system known as the "greenhouse effect" regulates the temperature on earth. Human activities have the potential to disrupt the balance of this system. As human societies adopt increasingly sophisticated and mechanized lifestyles, the amounts of heat-trapping gases in the atmosphere have been increased. By increasing the amount of these gases, humankind has enhanced the warming capability of the natural greenhouse effect. It is the human-induced enhanced greenhouse effect that causes environmental concern. It has the potential to warm the planet at a rate that has never been experienced in human history.

An international scientific consensus has emerged that our world is getting warmer. Abundant data demonstrate that global climate was warmed during the past 150 years. The increase in temperature was not constant, but rather consisted of warming and cooling cycles at intervals of several decades. Nonetheless, the long term trend is one of net global warming. Corresponding with this warming, alpine glaciers have been retreating, sea levels have risen, and climatic zones are shifting.

• The 1980s and 1990s are the warmest decades on record.
• The 10 warmest years in global meteorological history have all occurred in the past 15 years.
• The 20th century has been the warmest globally in the last 600 years.
• Most experts agree that average global temperatures could rise by 1 to 3.5 degrees Celsius over the next century.
• In Canada, this could mean an increase in annual mean temperatures in some regions of between 5 and 10 degrees.

Climate change is more than a warming trend. Increasing temperatures will lead to changes in many aspects of weather, such as wind patterns, the amount and type of precipitation, and the types and frequency of severe weather events that may be expected to occur. Such climate change could have far-reaching and/or unpredictable environmental, social and economic consequences.

E-mail : GofCClimateChange.LeschangementsclimatiquesGDC@rncan.gc.ca

Climate Change Campaign
http://www.panda.org/climate/

WWF's campaign is raising public concern about the need to cut emissions, pressing policymakers to introduce effective measures, and forming innovative partnerships with progressive businesses.

Global warming is increasingly being recognized as an urgent problem that affects people's everyday lives, but one that can be solved.
Let's have a look at WWF's "Innovative Solutions for a Living Planet"

Calling all in the business community… It's time to wake up and smell the carbon!

Shareholders, customers and the media are increasingly asking whether companies are acting responsibly. Soon, we believe, they'll be asking whether a company is preparing for the future with its own climate change policy and CO2-reduction plan.

Global warming isn't going to go away on its own. Making increasingly better use of resources in manufacturing processes and creating better-performing products with ever-lower energy demands has to become part of normal business practice if we are to crack this problem.

Business has a vital role in bringing to market and promoting technologies that reduce carbon dioxide emissions.
WWF is looking for forward-looking companies keen to turn a necessity into a business advantage.

We believe there are enormous opportunities for businesses to improve their standing and their bottom line through actions that cut CO2 emissions.

We argue that what companies need to do to improve their efficiency of resource use and to reduce CO2 emissions can be entirely compatible with their aim of improving shareholder and stakeholder value.
WWF has set up "Climate Savers" to strike deals with leading corporations prepared to make innovative new commitments.
We announced the first two agreements this year with Johnson & Johnson and IBM.

Johnson & Johnson pledged to reduce its global warming emissions worldwide 7% below 1990 levels by the year 2010 while IBM has pledged to increase energy efficiency and use clean energy in reducing its CO2 emissions by an average of 4 per cent per year by 2004.

Other companies are also getting the message:
in Germany, AEG - the country's leading maker of household appliances, like refrigerators and vacuum cleaners - promised WWF it will sell only the most energy-saving models
in Japan, WWF has been engaging power companies, government ministries, local authorities and the public in developing wind power
in the Netherlands, WWF brought together energy companies, financiers, a TV station, a rock music band and government ministries to deliver the biggest-ever leap in numbers of new subscribers for "green electricity".
And at the Davos meeting of the World Economic Forum, held in January 2000, hundreds of business and government leaders agreed climate change is "the greatest challenge facing the world … (on which) business could most effectively adopt a leadership role." WWF aims to ensure that their words are not just more hot air.

Global Warming Report NewScientist
http://www.newscientist.com/global/global.jsp?id=ns9999625

In the Global Warming section of this New Scientist's Magasine website, you can find not only many recent (and old) press articles about Global Warming but also quite a few quite interesting and complete reports dedicated to the topic.
A rare collection of information.

Here are some Headlines

Latest News :
Kyoto blow : European efforts to save the Kyoto Protocol flounder as Japan fails to endorse a go-it-alone plan (11 Apr 01)
A real roasting : The world condemns Bush for sabotaging climate treaty (7 Apr 01)
Carry on regardless : Can the world go it alone if the US backs down on global warming ? (24 Mar 01)
Shattering the greenhouse : We have the technology to halt global climate change, so let's use it (10 Mar 01)

Recent Articles about Global Warming (some) :
Global Warming : Scientists warn global warming could catastrophically change the planetary processes that make the Earth habitable (19 Feb 01)
Dead seas : As temperatures rise, the fate of ocean life hangs in the balance (13 Jan 01)
High and dry : Don't blame global warming for every flood (9 Dec 00)
Smokescreen exposed : A new report suggests the Kyoto Protocol on climate change is unworkable (26 Aug 00)
Gas from the past : It took a handful of shells from a mountain under the Pacific to confirm carbon dioxide's central role in the drama of Earth's changing climate (22 Apr 00)
The hole story : Every year, about this time, the air above the Arctic teeters on the brink of an ozone-destroying frenzy. Just how bad will it get? Gabrielle Walker braved the Swedish winter to find out (25 Mar 00)
The heat is on : Global warming is accelerating faster than climate modellers predicted (4 Mar 00)
Burning backwards : Could cunning chemistry keep carbon emissions in check ? (29 Jan 00)

Global Warming FAQ : All you ever wanted to know about climate change

What is the greenhouse effect?
Warmth from the Sun heats the surface of the Earth, which in turn radiates energy back out to space. Some of this outgoing radiation, which is nearly all in the infrared region of the spectrum, is trapped in the atmosphere by so-called greenhouse gases. For instance, water vapour strongly absorbs radiation with wavelengths between 4 and 7 micrometres, and carbon dioxide absorbs radiation with wavelengths between 13 and 19 micrometres.
The trapped radiation warms the lower part of the Earth's atmosphere, the troposphere. This warmed air radiates energy - again, largely in the infrared - in all directions. Some of the radiation works its way up and out of the atmosphere, but some finds its way back down to the Earth's surface, keeping it hotter than it would otherwise be. This is the greenhouse effect.

Are water and carbon dioxide all we have to worry about?
No. Other gases can absorb infrared radiation and contribute to greenhouse warming. These include methane, ozone, CFCs (chlorofluorocarbons) and nitrous oxide (released by nitrogen-based fertilisers). Of these, methane is the most important. Its concentration in the atmosphere has more than doubled since pre-industrial times. Sources of methane include the biological activity of bacteria in paddy fields and the guts of cattle, the release of natural gas from landfills and commercial oil and gas fields, and vegetation rotting in the absence of oxygen - for instance, in the depths of man-made reservoirs. Recent studies suggest this last source could be responsible for up to a fifth of global methane emissions. Molecule for molecule, other substances are even more potent greenhouse gases. A single molecule of either of the two most common CFCs has the same greenhouse warming effect as 10,000 molecules of CO2.

And the greenhouse effect is a thoroughly bad thing?
Not quite. Without it, the planet wouldn't be warm enough to support life as we know it. The problem is that beneficial natural levels of greenhouse gases in the atmosphere are being boosted by human activities, especially the burning of fossil fuels. If nothing is done to curb emissions of CO2, for example, the amount of CO2 in the atmosphere will probably be more than double pre-industrial levels by the end of the 21st century.

How do we know what these levels were?
The most informative measurements have come from bubbles of air trapped in Antarctic ice. These show that for at least the past 400,000 years, CO2 levels in the atmosphere have closely followed the global temperatures as revealed in ice cores, tree rings and elsewhere.
If it's all so precise, why is there so much confusion and uncertainty about global warming? Surely if we know how much CO2 is entering the atmosphere and how much energy each molecule can trap, we ought to be able to calculate the overall warming effect?
It's not that simple. For example there is no easy formula for predicting what future increases in CO2 levels will do to the average global temperature. While we can calculate that a doubling of CO2 in the atmosphere will force roughly 1 °C warming, the planet is more complex than that. It could respond by magnifying the effect, but it could also conceivably damp down the warming. These feedbacks involve essential planetary processes, such as the formation of ice, clouds, the circulation of the oceans and biological activity.

What effects are the main feedbacks likely to have?
One of the easiest effects to estimate is the "ice-albedo" feedback. As the world warms, ice caps will melt. As this happens, water or land will replace parts of the Earth's surface that were once covered with ice. Ice is very efficient at reflecting solar radiation into space, whereas water and land absorb far more. So the Earth's surface will trap more heat, increasing warming - a positive feedback. Less clear-cut is the impact of the extra water vapour likely to enter the atmosphere because of higher evaporation rates. This added water vapour itself contributes to the greenhouse effect, another positive feedback. But it may also increase cloud cover. The dominant effect of some low-altitude clouds is to shroud and cool the Earth - a negative feedback - but other clouds, such as cirrus, may trap heat at low levels, giving another positive feedback.

Disputes about how water vapour and clouds will influence global warming are at the heart of many of the disputes between mainstream scientists and the handful of greenhouse sceptics. Overall, the majority view is that positive feedbacks could amplify the warming effect by perhaps 2.5 times. But some sceptics believe the feedback effect could be neutral or even predominantly negative.

Why do sceptical scientists think that?
One reason is that something strange has been happening to warming trends in the past couple of decades. While ground-level temperatures around the world have gone up, the warming has failed to penetrate the atmosphere. The atmosphere has actually been cooling in some large areas three kilometres above the Earth. According to computerised climate models, the warming should spread right through the troposphere, the bottom ten kilometres or so of the atmosphere. Sceptics argue that if the models are wrong about how surface warming influences temperatures in the troposphere, they are also likely to be wrong about the movement of water vapour between the surface and the upper troposphere. That in turn may mean they are wrong about water-vapour feedback - one of the vital mechanisms behind global warming.

So does this mean there are some scientists who don't believe in the greenhouse effect or global warming?
No, this is a myth. All scientists believe in the greenhouse effect. Without it the planet would be largely frozen. And all scientists accept that if humans put more greenhouse gases in the atmosphere it will tend to warm the planet. The only disagreement is over precisely how much warming will be amplified by feedbacks. And there is a growing consensus that the average global warming of 0.6 °C seen in the past century - and particularly the pronounced warming of the past two decades - is largely a consequence of the greenhouse effect.

Climate Change
http://www.environment.fgov.be/Root/tasks/atmosphere/klim/set_fr.htm

(This site is published by the Federal Department of the Environment, Ministry for Social Affairs, Public Health and the Environment, Belgium)
This website is interesting for two main reasons :
1/ It provides a global approach of the greenhouse effect and its consequences on humanity destiny.
2/ Il gives access to quite a number of official documents, such as international treaties, national reports, legislation, policy documents, etc.
Consult for instance : United Nations General Assembly Reports and United Nations Framework Convention on Climate Changes or the Energy Charter

What is the Greenhouse Effect ?

In order to understand what the greenhouse effect really is, we have to begin by answering the question: how have we arrived at the present temperatures on earth?

The graph opposite here explains.
The heat on earth comes from the sun (1). That heat is partly absorbed by the earth itself (2), but a substantial part is reradiated also, into space (3). The heat absorbed is reradiated by the earth as infra-red radiation (4). The greenhouse gases: water vapour, carbon dioxide, methane, nitrous oxide... absorb this infra-red radiation and in turn reradiate it in the form of heat (5). These gases thus ensure that a considerable part of the heat from the sun remains within the atmosphere after all.
To some extent it works in the same way as a greenhouse: the heat of the sun can come in, while the gases ensure that the stored heat remains inside. Hence the name: greenhouse gases. If we were to lose all that reradiated heat, the average temperature on earth would be eighteen degrees below zero. It is not, however: in fact it is some fifteen degrees above zero.
Together the greenhouse gases do not even amount to one per cent of the earth's atmosphere. Nevertheless minor fluctuations in the amount of greenhouse gases can have major consequences. On the other hand, you cannot just ban the greenhouse gases, for that would cause the temperature on earth to drop. Too much is just as bad as too little, or in other words: tamper with the quantities of those gases, and you are in for trouble. Today one thing is crystal-clear: the amount of greenhouse gases in the atmosphere is increasing. This has been scientifically established (see table 1 for the figures).
Etc...