Green House Gases

There are some GHGs that are present in the atmosphere due to both natural processes and human activities. These include:

• Water vapour (H₂O)
• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Tropospheric ozone (O₃)

There are also some GHGs that are almost entirely due to anthropogenic sources. These include:

• Chlorofluorocarbons (CFC)
• Hydrofluorocarbons (HFC)
• Perfluorocarbons (PFC)
• Sulfur hexafluoride (SF₆)

Greenhouse gases and its effect

The greenhouse effect is unquestionably real and helps to regulate the temperature of our planet. It is essential for life on Earth and is one of Earth's natural processes. It is the result of heat absorption by certain gases in the atmosphere (called greenhouse gases because they effectively 'trap' heat in the lower atmosphere) and re-radiation downward of some of that heat. Water vapor is the most abundant greenhouse gas, followed by carbon dioxide and other trace gases. Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C). So, the concern is not with the fact that we have a greenhouse effect, but whether human activities are leading to an enhancement of the greenhouse effect by the emission of greenhouse gases through fossil fuel combustion and deforestation.

Global Warming

According to climate models, global warming could change our current world climate zones, which would affect where crops are grown and even drive some plant and animal species to extinction, all in the next 100 years.

Al Gore brought the issue to the big screen. Global warming -- what impact could it really have on our world? Geographer Jack Williams says, based on his new analyses of climate forecasting models, we're headed for major change -- fast.

"One of the things that we can definitely say that the more carbon dioxide we put into the atmosphere, the models very clearly show more of a warming that takes place in the U.S. and worldwide," said Williams, of the University of Wisconsin.

How much warming? With levels of CO₂ continuing to rise, Williams suggests areas of the world that currently have a tropical climate will be much warmer and drive vegetation and animal life north. Williams believes these changes would lead to the spreading of Malaria northward, more catastrophic natural disasters and overall greater human health risks.

"Even a few degrees Celsius can make a major difference in terms of where species grow and how well they thrive," Williams said.

As North America came out of the last Ice Age, spruce trees moved northward. Williams said the same thing will happen, potentially driving plant and animal species into extinction if they can't adapt to the changes fast enough. "Species can migrate in response to climate change, but there's the question of how quickly can they migrate, and will these climate changes over the next century be so rapid that species will be unable to keep up," Williams said.

Williams said that's why we need to take action now -- because later will be too late.

Norway – The Land of Midnight sun

Norway is witness to the fascinating nature’s mystery caused by the tilting of the Earth’s axis. This country, which is at the northern most corner of the European continent, is known as ‘the land of midnight sun’. The sun never sets here!

The Earth’s axis is tilted at 23.5 degrees from the center. Due to this reason, during the months of May to July the North Pole is nearer to the sun. In the same manner the South Pole is nearer to the sun from the months of November to January. Since Norway’s northern part is near the North Pole, the sun is visible throughout the night.

Why does the sun never set here? Why is the sun visible even during sunset time? Why the sun continues to be visible in the middle of the night? As the impact of Earth’s rotation is lesser nearer the poles, the movement if the sun appears to be slower compared to the other regions of the Earth. The sun appears to float on the horizon in the evening and never appears to set, which is why the sun is visible in this region all 24 hours!

During the months of May to July the sun remains visible at midnight in the North Pole region. After six months there is no sunrise in this part of the world. But surprisingly it is not dark during daytime and a misty light envelops the whole region.

At this time of the year the ‘midnight’ sun appears at the South Pole. As there is no habitation in this region there is no one to witness this spectacle.