Did you know that water vapour is the most common greenhouse gas? But there are others that are very important too. Some occur naturally and some come from human activity.
In the last century, carbon dioxide levels in our atmosphere increased by more than 25%. The six hottest years in recorded history have all occurred in the last decade.                                                                                               Scientists predict that in 50 years the Earth will be 3-5 degrees hotter than it is today, leading to the melting of far larger chucks of polar ice caps, and a rise of up to 14 feet in global sea levels. This could cause some islands to disappear

Greenhouse Effect, Climate Change,
and Global Warming

The Greenhouse Effect: Scientists are sure about the greenhouse effect. They know that greenhouse gases make the Earth warmer by trapping energy in the atmosphere

Climate Change: Climate is the long-term average of a region's weather events lumped together.  Climate change represents a change in the long-term weather patterns. They can become warmer or colder. Annual amounts of rainfall or snowfall can increase or decrease.

Global Warming: Global warming refers to an average increase in the Earth's temperature, which in turn causes changes in climate. A warmer Earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans. When scientists talk about the issue of climate change, their concern is about global warming caused by human activities.

Consequences of Climate Change

Without action, the world's average temperature is very likely to change more rapidly during the 21st century than during any natural variations over the past 10,000 years

Climate changes have occurred naturally in the past, and some regional changes have been significant. But globally, our climate has been relatively stable for the past 10,000 years.

The rate of global temperature change over the next 100 years will almost certainly be unlike anything human civilization has experienced before, if the world does not take action to reduce greenhouse gas emissions.

Climate change is not just rising temperatures

Many countries might expect to see changes in wind patterns, storm tracks, occurrence of frosts, and the frequency of heavy rainfall events. These effects will become more pronounced as time goes on.

The effects of climate change will continue beyond 2100. Sea-levels will continue to rise for centuries after greenhouse gas concentrations have stabilized

The climate system takes time to change. In particular the deep oceans take centuries to heat up when the atmosphere above them warms. This means that oceans will continue to heat up, and therefore expand causing sea levels to rise, even if greenhouse gas concentrations in the atmosphere are no longer increasing.

The climate system is very complex and there are still uncertainties about future climate changes

Future climate change depends on how much greenhouse gases are emitted in future (and hence on the development pathway of human society) and also how the Earth responds to the increased heating. So we cannot be precise about how much the climate will change in the future. We are generally sure of the direction of change (for example, the world will become warmer, and global average sea-levels will rise), and we can give plausible ranges for those changes (for example, the range of emissions looked at by the IPCC (Intergovernmental Panel on Climate Change)is expected to increase the world's average temperature by between 1.1 and 6.4 degrees Celsius by 2100).

To manage the wide-ranging risks resulting from climate change, we need to account for the full range of those possible outcomes. We cannot rely on only the best case scenario coming true - we need to be prepared for the other possible scenarios as well.