THE CLIMATE SYSTEM, FEEDBACKS, CYCLES AND SELF-REGULATION

Our climate is a system that it is controlled by positive and negative feedbacks as well as natural cycles.

As a system, we can distinguish 5 key components ( the atmosphere, hydrosphere, biosphere, cryosphere and lithosphere ). These components intetract between them through a series of cycles that link every component to another.

 

There are a lot of natural cycles, but a good example is the water cycle.In the picture below you can observe how it works.

To determine the climate state of the Earth is needed to undesrtand the feedbacks that operate in the climate system. There are 3 key feedbacks, water vapour feedback, ice albedo feedback and the radiation feedback.

The water vapor feedback is a positive feedback (in a mathematical way) and has three components: temperature, evaporation and water vapour. If we incresase the temperature, the evaporation increases.

The ice albedo feedback has a significant influence on the climate. The ice reflects so much solar radiation back to the atmosphere because it has a high albedo. On the other hand, the ocean tends to absorb more that it reflects because it has a low albedo, for this reason the ocean is heating. This means that the warming of the ocean will melt the sea ice.

The last feedback is the radiation feedback, it is a good example of negative feedback. It works by cooling an object when the temperature is rising. All objects give off radiation, but the warmer a body is the more radiation it gives off.

To sump up, climate can be conceived as a system that involves different components. The mixture of positive and negative feedbacks cooperates to a self-regulation of the climate system.

Key principles of climate change

This is the title of the introduction to the course. It makes me think about the keys, Which are they?
The first video introduces me to the greenhouse effect.
It's fundamental to understanding what keeps our planet warm and why our climate changes over time.The greenhouse, like the rest of the planet, receives incoming radiation from the sun, which passes easily through the glass, just as it does through the atmosphere. Some of that incoming sunlight is absorbed by the surfaces inside the greenhouse. And like all objects, the plants and the soil in the greenhouse re-emit heat radiation at long wavelengths that are invisible to us.

These gases work like a blanket around the planet.   

What are the main greenhouse gases?

Because of all the press coverage it has received in recent years, you may think that carbon dioxide (CO2) is "the big one". Though CO2's role is important, water vapor is actually the dominant greenhouse gas in Earth's atmosphere. Water vapor generates more greenhouse effect on our planet than does any other single gas. After water vapour, in rough order of importance the most important greenhouse gases are carbon dioxide (CO2), methane (CH4) and ozone (O3). There are a number of other gases that contribute to the greenhouse effect to a lesser extent; we'll mention these here in passing for reference, but not consider them further henceforth. These "lesser greenhouse gases" include nitrous oxide (N2O), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and chlorofluorocarbons (CFCs).

Further information in this link:  The Greenhouse Effect & Greenhouse Gases

What is the albedo?

It's also important the albedo concept (t is the ratio of reflected radiation from the surface to incident radiation upon it. Its dimensionless nature lets it be expressed as a percentage and is measured on a scale from zero for no reflection of a perfectly black surface to 1 for perfect reflection of a white surface.) This is a new concept for me but, it's really useful to understand why people is concern about the melting of ice caps, because it has a extrongly effect on the Earth's temperature.

After watching the video I have tried to reply to this questions:

• has your understanding of the greenhouse effect changed?
• should we adopt ‘the blanket effect’ as an analogy instead of ‘the greenhouse effect’?

In my opinion the video explained clearly the basic principles of the greenhouse effect and helped clarify my understanding. Also, I guess we have heard more about CO2 instead of water vapour because there are things we can do in order to reduce emissions.