The climate of the Earth is changing. It gets warmer. Over the last 100 years, the temperature of the Earth has risen by an average of about 0.6 °C. It may not sound as much, but in many places you can already see the results of the warmer climate – trees bloom earlier than usual, winters are milder, glaciers retreat and species of animals and plants that usually live further south are pushed north.
Intensification of the greenhouse effect is the main reason for the temperature rise. This intensification happens as a result of the formation of so-called greenhouse gases (carbon dioxide, CO2, from energy production and methane and nitrous oxide from agricultural production) resulting from human activities. The greenhouse gases rise up into the atmosphere where they form a layer around the Eart
Part of Earth's heat is lost to the atmosphere and further into space in the form of so-called heat rays. The greenhouse gases reflect the heat rays and direct them back to Earth. As the layer of greenhouse gases becomes denser, it reflects a larger part of the heat rays that previously passed through the atmosphere and into space. As a result, the Earth can no longer get rid of as much heat as before. That is why the Earth's temperature rises. Especially in the past 50 years, the formation of greenhouse gases due to human activities has increased strongly, augmenting the greenhouse effect.
Climate researchers use models to predict how the Earth's climate will develop. The climate models are based on information about factors that affect the climate, such as the atmosphere, the oceans, ocean currents, ice and snow as well as land surfaces. The models are constantly becoming more complex, and the analysis of the future climate requires large computer systems.
The researchers obtain realistic projections of the future climate by feeding the climate models with different predictions about how the Earth’s population, energy consumption, technology, production etc. develop. The most advanced climate models predict an average temperature increase between 1.4 and 5.8 °C over the next approx. 100 years depending on how society evolves. Some of the consequences are that the large ice masses of the Arctic and Antarctica will begin to melt, the air and ocean currents will change, the water levels in the oceans will rise, more precipitation will occur in some areas and draught in others, and the weather will be more extreme.