PENGUINS FACE EXTINCTION DUE TO GLOBAL WARMING CLIMATE CHANGE

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Half to three-quarters of major Antarctic penguin colonies could be damaged or wiped out if global temperatures are allowed to climb by more than two degrees Celsius (3.6 degrees Fahrenheit), according to a report released Wednesday on October 8th, 2008.

A two degree hike would threaten 50 percent of breeding grounds of emperor penguins, and 75 percent of Adelie penguin colonies, said the study, released by the World Wildlife Fund (WWF) at the World Conservation Congress in Barcelona.

The United Nation's panel of climate change scientists has warned that earth's average temperature could increase more than two degrees Celsius by century's end even if major efforts are made curb greenhouse gases, and twice as fast under "business-as-usual" scenarios.

A reduction in the sea ice is also likely to have a knock-on effect on the abundance of krill, which is a vital food source for penguins, concludes the report.

"Penguins are very well adapted to living in the cold and extreme conditions of Antarctica," said the WWF's Juan Casavelos, noting that warming has already contributed to a reduction in populations.

"If temperatures increase by another two degrees these icons of the Antarctic will be seriously threatened," he said.

A two-degree increase above pre-industrial temperatures is widely viewed among scientists as the threshold beyond which climate change will have severe consequences for Earth's ecosystems, including for humans.

While curbing global warming is the only viable long-term solution, conservationists have called for an expanded network of marine protected areas to reduce pressure on penguins, and for tighter management of krill and finfish fisheries the Southern Ocean.

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GLOBAL WARMING - CLIMATE CHANGE RESEARCH

It was realised by the mid-18th century that some gases in the Earth's atmosphere, such as carbon dioxide, trap heat and keep the Earth warm. At the start of the 20th century, a Swedish scientist named Svante Arrhenius put forward the idea that human emissions of carbon dioxide would eventually raise temperatures. He didn't see this as a particularly bad thing, and most scientists at the time were sceptical that humans could burn fossil fuels fast enough to have a noticeable impact at all.

So, although the idea that mankind could influence Earth's global temperature was proposed over a century ago, it wasn't until relatively recently that scientists were able to confirm this with confidence. Data had to be gathered from around the world, technology had to develop to allow us to analyse that data, and basic advances in physics and other disciplines had to come about before we could understand it. What we now know about the climate is thanks to literally generations of dedicated researchers.

However, it is also easier to observe human caused climate change today because we’ve put so much more carbon dioxide into the climate system over the past century that the impacts of climate change are now clearly visible, affecting people and ecosystems all over the world.. More cars, more factories, and more power plants – all are changing the climate faster than was previously possible – and causing more obvious changes.

Taking the planet's temperature
To get an accurate picture of how warm the Earth is, you need measurements from all over because the whole planet does not heat up at the same rate. In fact, some parts might even cool down while the world as a whole heats up. Also, many temperature readings are needed over time to develop an accurate long-term picture. In order to develop a global temperature history, researchers have had to travel to the farthest corners of the Earth, and come up with ways to "go back in time".

Some sources of past temperature data:

Historical records – Includes sources like ship's logs, farmer's diaries and newspaper articles. When carefully evaluated these can provide can provide both quantitative and qualitative data.

Personal accounts and oral histories – Useful information can be gathered especially from the older generations of indigenous people who have always relied on nature for their survival, and so are particularly observant of changes over the past decades.

Direct (e.g. thermometer) measurements – Only go back around 300 years, and are very sparse until about 150 years ago. Also, differences in thermometer types and other variables have to be taken into account.

Data collected by balloon and satellite – Very useful, but only available since 1979.

Tree ring thickness – Width and density varies depending on growing conditions.

Ocean and lake sediments – Billions of tons of sediments accumulate each year. The tiny preserved fossils and chemicals in layers of sediment can be used interpret past climate.

Coral skeletons – The water temperature that the coral grew in can be determined from trace metals, oxygen and the isotopes of oxygen contained in its skeleton.

Fossil pollen – Each plant has uniquely shaped pollen. Knowing what plants were growing at a particular time in the fossil record lets scientists make inferences about what the climate was like at the time.

Ice cores – Over the centuries snow falling on high mountains and the polar ice caps packs down and becomes solid ice. Dust and air bubbles trapped in this ice provide valuable climate data. For example, the air trapped in the ice serves as a record of carbon dioxide concentrations across the millennia.

Observed melting – Rates of glacial retreat, permafrost thaw, shrinking polar ice caps and reduction in Arctic sea ice are indicators of both short and long term climate change.

The important thing is not to look at any one source of data independently, but instead to take them together. This produces a scientifically compelling picture of a warming world that matches with the corresponding increase in greenhouse gasses.

Predicting the climate future
Global climate models are mathematical representations of the real world's climate. Some models are attempts by scientists to boil the complex behaviour of the climate down to (comparatively!) simple formulas in an attempt to understand the forces at work. However, when people talk about specific predictions of long term climate behaviour they are usually talking about general circulation models. In these models, the equations are tweaked (within reason) until the model is able to predict past and present conditions, as accurately as possible, when tested against actual observations of past and present conditions.

Since it's impossible to know every last variable, and because the model will never match the real world perfectly, scientists compensate by running each model over and over, while making tiny changes to the starting conditions (increasing the wind speed over Detroit by one percent, for example) and other factors. This way they can get an idea of the different possible outcomes. If one result occurs more frequently then another then it's the more likely outcome.

In the end, each model predicts a range of possible outcomes. For example, the IPCC, taking into account all of the different available models, settled on a projected global temperature rise of 1.4 – 5.8° Celsius (about 3 to 8° Fahrenheit). No one can say exactly how much the temperature will increase over the next hundred years, but with a couple of caveats it is a safe bet that it will be within this range.

The caveats
One thing climate models can not predict are all the possible effects of feedback mechanisms, which might help stabilise the climate or cause the climate to change much faster and in unpredictable ways. Of course, it would be irresponsible to ignore the climate models and hope for the best because of these uncertainties. See our feedback effects page for more information.
Another thing these models can not really predict is human behaviour, and ingenuity. We could burn more fossil fuels than expected, and end up with a hotter planet then even the worst case scenario. Or we could deploy renewable energy and energy efficiency solutions faster then thought possible – eliminating the likelihood of the higher temperature ranges.

US National Oceanic and Atmospheric Administration – Climate proxy data
American Institute of Physics - History of climate change research

The Climate Change Connection – Climate research
ClimatePrediction.Net – Distributed computing climate modelling project (join the Greenpeace team on the project!)

GLOBAL WARMING - DEFORESTATION

Deforestation and forest degradation are both a cause and a result of climate change. Plants absorb carbon dioxide and use it to grow, but when they decay or burn the carbon dioxide is released again. Decaying plants also produce methane, a greenhouse gas more potent than carbon dioxide.

So deforestation and forest degradation are doubly damaging, because greenhouse gasses are released (e.g. through forest fires, or using the cut trees as firewood), while at the same time the number of carbon dioxide absorbing trees are reduced. Thirty percent of the carbon dioxide added to the atmosphere over the past 150 years is thought to come from deforestation, but this is a small amount compared to what is still stored in forests. The Canadian and Russian boreal forests alone hold 40 percent of the world's carbon stocks.

How climate change is hurting forests?
Changes in temperature ranges and precipitation can harm forests. Droughts and forest fires are expected to increase due to climate change. Forest fires can be a normal part of forests - they clear dense brush and are part of some species lifecycle. However, forests over stressed by human activity and drought can also be devastated by them. There are already indications that the Amazon is drying out, which could lead to a dangerous feedback of fires and desertification.

Invasive insect species may also damage forest health. Insects play a role in boreal ecology - they decompose litter, supply food for birds and small animals, and eliminate diseased trees. But insect attacks are likely to increase in frequency and intensity as established forests succumb to the physiological stress associated with warmer, drier conditions. As the Arctic warms, some invasive insect species, which the colder climate normally helps hold in check, are already increasing in population.

Replanting and sustainable forestry
It's worth noting that proper sustainable forestry practices do not cause a net increase of carbon dioxide in the atmosphere because a new tree is grown for every one cut down. By contrast, clear cutting and converting forestland into to urban areas has a very high negative impact - because the forest is destroyed and replaced with heat absorbing pavement and buildings.

Obviously, re-forestation, sustainable logging and protecting ancient forests are essential to not increase the pace of climate change further - so long as these forests are not destroyed later (by future logging, forest fires, etc.).

However, to prevent dangerous human induced climate change, we need to address the main cause - the burning of fossil fuels and the release of industrial greenhouse gasses into the atmosphere.

Also see the Greenpeace forests campaign.

Help protect the world's ancient forests by buying only Forest Stewardship Council (FSC) certified wood, and products with post-consumer recycled content. You'll be saving vital habitat, and doing good by the climate at the same time.

More information:
Amazon under threat
Kyoto pitfalls
Greenpeace forest home wood shopping guide (Flash with audio)
Greenpeace paper buying guide

GLOBAL WARMING - GASES / EMISSIONS

The primary human source of carbon dioxide (CO2) in the atmosphere is from the burning of fossil fuels for energy production and transport. Changes in land use and deforestation also contribute significantly. Trees, for example, are natural 'carbon sinks' - they absorb carbon dioxide while alive and when they are destroyed, carbon dioxide is released into the atmosphere. Once in the atmosphere, most of the carbon dioxide stays there for 50 to 200 years, and some of it stays there indefinitely.

What are fossil fuels?

Oil, coal and natural gas are called fossil fuels because it is believed they are formed from the remains of plants and animals living millions of years ago. All fossil fuels are made up of hydrocarbons, and release carbon dioxide when burned.

Currently, fossil fuels are the primary source for almost 80 percent of the industrial world's energy. They are a non-renewable resource, so we'll eventually run out of them. However, if we want to avoid dangerous climate change we can only afford to burn less than one-fourth of the known oil, coal and gas reserves – burning any more will almost certainly release enough carbon dioxide to change the climate dramatically.

Who does the most burning?

The simple answer is that because industrialised nations have bigger economies and have been burning fossil fuels for a hundred years or more, they are responsible for most of the cumulative carbon dioxide emissions in the atmosphere. However, all nations are responsible to one degree or another.

This can, and should, change in the future. In some countries, it is changing today. Thanks to renewable energy technology and energy efficiency, economic success and fossil fuel use are no longer synonymous.

However, among the world's top economies, the US still stands out as the number one polluter. With less than 5 percent of the world's population, the US is the world's largest producer of greenhouse gases and is responsible for almost a quarter of global emissions of carbon dioxide.

But to look at carbon dioxide emissions only by country is perhaps too narrow. The same question applies per business or even individual. Someone driving a gas-guzzler of a car is burning more fossil fuels then someone with a more efficient car, for example. Of course nations and businesses must be held accountable, but as individuals we each also make decisions the affect the climate.

Although carbon dioxide is the most significant greenhouse gas in terms of human emissions, we are also adding others to the atmosphere that are even better at trapping heat. The Kyoto Protocol covers emissions of five gases beside carbon dioxide: methane, nitrous oxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6). In addition, water vapour is also a greenhouse gas, but its presence in the atmosphere is not directly affected by human activity.

Gasses with natural and significant human sources:

Methane (CH4)
Methane is the second biggest contributing greenhouse gas, and is responsible for 20 percent of the enhanced (human caused) greenhouse effect. It is about 23 times more powerful a greenhouse gas than carbon dioxide, and has an atmospheric lifetime of roughly 12 years.

Sources of methane include decomposing organic waste (in nature and in garbage dumps), and the raising of livestock. It's also emitted during the production and transport of coal and natural gas. Although natural sources exist, human activities are significantly contributing to the amount of methane in the atmosphere. Globally, atmospheric concentrations of methane have increased by about 150 percent since 1750, and are now at higher levels than in the last 400,000 years. Once in the atmosphere, methane decays into carbon dioxide over a period of a few years.

Nitrous oxide (N2O) Nitrous oxide is 296 times more powerful a greenhouse gas than carbon dioxide, and remains in the atmosphere for 114 years. It is naturally emitted from oceans and soils, but human driven sources are increasing its atmospheric concentrations. Uses include some agricultural (mostly nitrogen fertilization) and industrial activities, and it is created during combustion of fossil fuels and other organic matter. Nitrous oxide also has a variety of direct uses - including as an aerosol propellant and as an anaesthetic (i.e. "laughing gas").

Artificial gasses with very high global warming potential:

Hydrofluorocarbons (HFCs)
HFCs make up only a small portion of greenhouse gas emissions, but they are extremely potent greenhouse gases. Depending on the exact type of HFC, they are up to 20,000 times more powerful greenhouse gasses than carbon dioxide, and have atmospheric lifetimes of up to 260 years.

Some uses of HFCs are in refrigeration (both commercial and domestic), in air-conditioning (homes, cars, offices etc), and they are also used as foam blowing agents, solvents, fire fighting agents and aerosol propellants. HFC use and production surged after they were actively promoted as replacement refrigerants when a phase out of the ozone depleting chlorofluorocarbons (CFCs) was mandated by the Montreal Protocol. This is despite Greenpeace's successful Greenfreeze project, which proved that more natural and benign alternatives are commercially viable for refrigeration. In fact, safer alternatives exist for almost every use of HFCs - making them a good target for emission reductions.

Perfluorocarbons (PFCs)
PFCs are from 5,700 to 10,000 times more powerful greenhouse gasses (depending on the exact type) than carbon dioxide, and have an atmospheric lifetime of up to 50,000 years. PFCs are by-products of aluminium smelting. They are also used in semi-conductor manufacture, and as substitutes for ozone depleting chemicals. Emissions of PFCs are small even compared to HFCs. However, given their potency, long lifetimes and availability of alternatives already on the market, PFCs should be urgently phased out.

Sulphur Hexafluoride (SF6)
Sulphur Hexafluoride is the most potent greenhouse gas evaluated by the Intergovernmental Panel on Climate Change. It is 23,900 times more powerful a greenhouse gas than carbon dioxide, and has an atmospheric lifetime of 3,200 years. It has a number of uses including in Nike Air shoes, car tyres, for electrical insulation, semiconductor manufacture, and in the magnesium industry.

Like PFCs, the effects of Sulphur Hexafluoride to date are fairly small. However, since it is a very persistent and potent greenhouse gas, there is concern about its continuing build up in the atmosphere. Given its potency, long lifetime and availability of alternatives already on the market, Sulphur Hexafluoride should be urgently phased out.

The European Union is currently designing legislation to control emissions of these gases. For more information see the Greenpeace's EU unit website.

Water and ozone:

Ozone (O3)
Ozone occurs both naturally, and from human activities. It is present both in the upper atmosphere, where it forms the ozone layer shielding us from harmful levels of ultraviolet solar radiation, and in the lower atmosphere, where it is the main component of smog.

Some people confuse the issue of ozone depletion with climate change. In reality, they are separate but related. The man made chemicals that destroy the ozone layer are greenhouse gases, as are some of the chemicals that are replacing them. Also, as the Earth's lower atmosphere warms and traps more heat, the upper atmosphere (where the ozone layer is) becomes colder, which facilitates the chemical reactions that damage the ozone layer.

Water vapour (H2O)
Water vapour is the most abundant greenhouse gas. The direct effect of human activity on global water vapour concentrations is thought to be negligible. However, water vapour is important for climate change because of an important feedback effect. Warmer air can hold more moisture, enhancing climate change. The exact size of this important feedback remains to be determined by scientists.

Editor's note: Gases are commonly compared to one another according to their Global Warming Potential (GWP), which refers to their warming effect over a set time compared to the same amount (by weight) of carbon dioxide. Comparing GWPs is useful because it takes into account both the warming potential of each molecule of a gas, and its atmospheric lifetime (how long it stays in the air). Carbon dioxide is the commonly accepted point of reference (with a GWP of 1) because it is the most significant greenhouse gas from human activities.

For simplicity, this page refers to the warming potential of each gas relative to carbon dioxide over a 100-year period. This is the same as its GWP with a hundred year benchmark. Thus, a kilogram of carbon dioxide emission has a GWP of one, while a kilogram of nitrous oxide has a GWP of 310 - which we have expressed here as "nitrous oxide is 310 times more powerful a greenhouse gas than carbon dioxide".

However, it is worth noting that since some gases will stay in the atmosphere much longer than 100 years, their total greenhouse effect over time is actually greater than expressed here.
Atmospheric lifetime = How long the gas stays in the atmosphere.

GLOBAL WARMING - THREAT TO OCEANS

The ocean and its inhabitants will be irreversibly affected by the impacts of global warming and climate change. Scientists say that global warming, by increasing sea water temperatures, will raise sea levels and change ocean currents.

Ocean Currents

The water in our world's oceans is always moving – pulled by tides, blown by waves, and slowly circulating around the globe by the force of the Great Ocean Conveyor Belt (also called thermohaline circulation). The Conveyor is powered by differences is water temperature and salinity, and one of its most well known parts, the Gulf Stream, is what gives Europe it's relatively mild climate.

Aside from keeping Europe warm, and playing an important role in the global climate, the Conveyor provides an up welling of bottom ocean nutrients, and increases the oceanic absorption of carbon dioxide.

What could go badly wrong?

Worryingly, recent studies warn that we may already have evidence of a slower Conveyor circulation over the Scotland-Greenland deep ocean ridge. And while the Conveyor appears to have operated fairly reliably over the past several thousand years, an examination of ice cores from both Greenland and Antarctica shows that this has not always been the case. In the more distant past, changes to the Conveyor circulation are associated with abrupt climate change.
In short, dilution of the ocean's salinity - from melting Arctic ice (such as the Greenland ice sheet) and/or increased precipitation - could switch off, slow down or divert the Conveyor. This dramatic cooling would mean a massive disruption to European agriculture and climate, and impact other sea currents and temperatures around the globe.

Sea Level Rise

A global average sea level rise of 9-88 cm (3.5–34.6 inches) is expected over the next hundred years, thanks to the greenhouse gasses we have emitted to date and likely future emissions. This will come in roughly equal measure from melting ice and from thermal expansion of the oceans (water expands as it heats up).

Even this comparatively modest projected sea level rise will wreak havoc. Coastal flooding and storm damage, eroding shorelines, salt water contamination of fresh water supplies, agricultural areas, flooding of coastal wetlands and barrier islands, and an increase in the salinity of estuaries are all realities of even a small amount of sea level rise. Some low lying costal cities and villages will also be affected. Resources critical to island and coastal populations such as beaches, freshwater, fisheries, coral reefs and atolls, and wildlife habitat is also at risk.

The West Antarctic ice sheet

Only four years ago, it was commonly accepted that the West Antarctic ice sheet was stable, but unexpected melting in the region is causing scientists to re-think this assumption.

In 2002, the 500 billion tonne Larsen B ice shelf, which covered an area twice the size of greater London, disintegrated in less than a month. This did not directly add to sea level rise since the ice shelf was already floating, but it was a dramatic reminder of the effects of warming in the area.

Then in 2005, the British Antarctic Survey released findings that 87 percent of the glaciers on the Antarctic Peninsula have retreated over the past 50 years. In the past five years, the retreating glaciers have lost an average of 50 metres (164 feet) per year.

Potentially, the West Antarctic ice sheet could contribute an additional six metres (20 feet) to sea level rise. Although the chances of this are considered low in the Intergovernmental Panel on Climate Change’s Third Assessment report, recent research indicates new evidence of massive ice discharge from the ice sheet.

The entire Antarctic ice sheet holds enough water to raise global sea levels by 62 metres (203 feet).

The Greenland glaciers

In July 2005, scientists aboard the Greenpeace ship Arctic Sunrise made a stunning discovery - evidence that Greenland’s glaciers are melting at an unprecedented rate. It's just more evidence that climate change is no longer on the horizon, it has arrived at our doorstep, and if you live in a coastal city, that's not just a figure of speech.

Findings indicated that the Kangerdlugssuaq Glacier on Greenland's east coast could be one of the fastest moving glaciers in the world with a speed of almost 14 kilometres per year. The measurements were made using high precision GPS survey methods. In addition, the glacier unexpectedly receded approximately five kilometres since 2001 after maintaining a stable position for the past 40 years.
Greenland’s massive ice sheet locks up more than six percent of the world’s fresh water supply, and it is melting much faster than expected. If Greenland were to melt fully, it would cause sea levels around the globe to rise by nearly 20 feet. Even measurements of four to five feet of sea level rise could mean that places like New York, Amsterdam, Venice and Bangladesh will experience flooding in low lying areas.

The alarming retreat of the Kangerdlugssuaq Glacier suggests that the entire Greenland ice sheet may be melting far more rapidly than previously believed. All current scientific forecasts for global warming had assumed slower rates of melting. This new evidence suggests that the threat of global warming is much greater and more urgent than previously believed.

Habitat Loss

Temperature rises are impacting on the entire marine food web. For example, phytoplankton, which feeds small crustaceans including krill, grow under sea ice. A reduction in sea ice implies a reduction in krill - and krill feeds many whale species, including the great whales.

Whales and dolphins strand themselves in high temperatures. The great whales also risk losing their feeding grounds, in the Southern Ocean around Antarctica, because of the melting and collapse of ice shelves.

Whole species of marine animals and fish are directly at risk due to the temperature rise - they simply cannot survive in warmer waters. Some penguin populations, for example, have decreased by 33 percent in parts of Antarctica, because of habitat decline.

An increasing occurrence of disease in marine animals is also linked to rising ocean temperatures.

GLOBAL WARMING - BROAD SCIENTIFIC CONSENSUS

Climate change is a reality. Today, our world is hotter than it has been in two thousand years. By the end of the century, if current trends continue, the global temperature will likely climb higher than at any time in the past two million years. While the end of the 20th century may not necessarily be the warmest time in Earth's history, what is unique is that the warmth is global and cannot be explained by the natural mechanisms that explain previous warm periods. There is a broad scientific consensus that humanity is in large part responsible for this change, and that choices we make today will decide the climate of the future.

How we are changing the climate?

For more than a century, people have relied on fossil fuels such as oil, coal and gas for their energy needs. Burning these fossil fuels releases the global warming gas carbon dioxide into the atmosphere. Other, even more potent, greenhouse gasses are also playing a role, as is massive deforestation.

"The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action."-- Joint statement by 11 national science academies to world leaders (full text)

What we know?

While there are still uncertainties, particularly related to the timing, extent and regional variations of climate change, there is mainstream scientific agreement on the key facts:

Certain gasses, such as carbon dioxide, in the atmosphere create a "greenhouse effect", trapping heat and keeping the Earth warm enough to sustain life as we know it.

Burning fossil fuels (coal, oil, etc.) releases more carbon dioxide into the atmosphere. Although not the most potent greenhouse gas, carbon dioxide is the most significant in terms of human effects because of the large quantities emitted.

Carbon dioxide concentrations in the atmosphere are now the highest in 150,000 years.

The 1990's was most likely the warmest decade in history, and 1998 the warmest year.

There is also widespread agreement that:

A certain amount of additional warming - about 1.3º Celsius (2.3º Fahrenheit) compared to pre-industrial levels - is probably inevitable because of emissions so far. Limiting warming to under 2° Celsius (3.6°F) is considered vital to preventing the worst effects of climate change.

If our greenhouse gas emissions are not brought under control, the speed of climate change over the next hundred years will be faster than anything known since before the dawn of civilization.

There is a very real possibility that climate feedback mechanisms will result in a sudden and irreversible climate shift. No one knows how much global warming it would take to trigger such a "doomsday scenario".

There is, in fact, a broad and overwhelming scientific consensus that climate change is occurring, is caused in large part by human activities (such as burning fossil fuels), and if left un-checked will likely have disastrous consequences.

Furthermore, there is solid scientific evidence that we should act now on climate change - and this is reflected in the statements by these definitive scientific authorities.

Joint statement from 11 national academies of science
Issued 7 June 2005, by the national science academies of the United States, United Kingdom, France, Russia, Germany, Japan, Italy, Canada, Brazil, China and India, the statement begins with:

Climate change is real
There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001). This warming has already led to changes in the Earth's climate.

The statement goes on to conclude:

We urge all nations, in the line with the UNFCCC principles, to take prompt action to reduce the causes ofclimate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies.

Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change (IPCC) was set up by the United Nations in 1988 to assess the scientific, technical and socio-economic information relevant for the understanding of the risk of human induced climate change. About 1,000 experts from around the world are involved in drafting, revising and finalizing IPCC reports. About 2,500 experts take part in the report review process. Thus, the IPCC represents a global consensus of the world's climate change experts. From the IPCC's most recent scientific assessment:

“[M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations".

"There is new and stronger evidence that most of the observed warming over the last 50 years is attributable to human activities".

"About three quarters of the anthropogenic [human caused] emissions of CO2 to the atmosphere during the past 20 years are due to fossil fuel burning”.

The assessment goes on to warn that there is a risk of feedback loops, which could cause runaway climate change, and that the global warming to date is already having an effect on the biosphere.

Learn more: http://nationalacademies.org/onpi/06072005.pdf