Today, the concentration of CO2 and other greenhouse gases far exceeds what has been the natural level over the past 650,000 years. The amount of CO2 is 35% higher than before industrialization, and the amount of methane has more than doubled.

The consequences are already visible

In many places on the planet changes in weather patterns are observed. In some places there is more precipitation than previously, while other places are affected by high temperatures.

It is, however, difficult to distinguish accurately between climatic influences and other man-made influences on the planet, such as agriculture and infrastructure. Nevertheless, the United Nations Intergovermental Panel on Climate Change notes that climatic changes have consequences:  

·      Globally, man-made warming has had a noticeable influence on many weather systems, animals and plants.

·      Over the past 30 years, researchers have collected sets of data about how climate changes influence weather systems, animals and plants. Out of 29,000 sets of data, just under 26,000 have shown changes in line with what would be expected to occur concurrently with global warming.

This correlation between observed and expected changes is, with a very high probability, attributable to non-natural circumstances.

Arctic areas, includingGreenland, are also noticeably affected. Climate changes there are more pronounced than in other areas on the planet.

For example, a new survey by the Zackenberg research station inGreenlandhas shown that while spring season on the planet has advanced on average five days per decade, at Zackenberg it has advanced 30 days over the past ten years.

The temperature in theArcticover the past century has risen twice as much as for the rest of the planet. Warming means that ice and snow are melting on an increasingly larger part of the surface of the ice cap. The area where ice and snow are melting has increased in size by 30% over the past 30 years.

This gives rise in part to an increased flow of melt water into the sea and also to meltwater seeping through the ice. The seeping water causes the ice to flow faster across the surface of the land and melt faster.

Melting from land based ice caps contributes to higher water levels on the seas and oceans, and at the same time the increased flow of fresh water may influence ocean currents and thus the distribution of heat across the globe. In addition to increased melting of glaciers and ice caps, the amount of ice in the seas and oceans has been decreasing over the last decades. This has an impact on reflection of the sun's rays.

Future global consequences

Over the past 100 years (1906 – 2005), the temperature of the Earth has risen by0.74°C. As a comparison, warming after the last ice age was globally 4 –7 °Cand that took place over 5000 years.

A warming that according to the United Nations Intergovermental Panel on Climate Change was ten times slower than that which we are experiencing today.

Over the past 25 years, the Earth's temperature has risen by 0.18 ºC per decade, which is more than twice as much as the average for the past 100 years.

One of the contribution reports for the United Nations Intergovermental Panel on Climate Change Fourth Assessment Report, "Consequences and Climate Adaptation", evaluates the future consequences that climate changes are expected to contribute to. Some of the consequences are serious for man, animals and plants. 

·      In the middle of this century it is expected that wet areas will get wetter and dry areas will get drier.

·      Up to a sixth of the planet’s population is expected to have problems with a lack of water, as the water supply in many regions depends upon water resources such as snow and ice melting.

·      20-30% of the planet’s animal and plant species are at risk of extinction if the average global temperature rises by more than 1.5 –2.5 °Cabove the 1990 level.

·      Most coral reefs are expected to turn pale with a local warming of 1 ºC, and risk extinction if the warming exceeds 2 ºC.

·      Crop yields will decrease in areas near the equator, and more people will be affected by famine.

·      When the seas rise, coasts will be eroded and a large part of the world population in low-lying areas will be in danger of flooding.

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