CLIMATE MODELS

Climate models are designed to simulate the responses and interaction of the oceans and atmosphere and to account for changes to the land surface, both natural an human induced.

The models predict that the Earth's average surface temperature will rise. Scientist predict the range of LIKELY temperature increase by running many possible future scenarios. However, these predictions are uncertainly because scientist don't know what choices people will make to control greenhouse gasses emission.

There is a variability between models because not only greenhouse gasses affect but also the effect of aerosols, climate feedbacks (snow and ice, water vapour, clouds and carbon cycle) and ocean cycles like El Niño and La Niña have several influence on temperature changes. 

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle.La Niña is sometimes referred to as the cold phase (shrot-term cooling influence on global surface temperatures) and El Niño as the warm phase (we expect temperatures to be above the projection). These desviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

Further information about El Niño y La Niña cycle:
https://www.climate.gov/enso
http://oceanservice.noaa.gov/facts/ninonina.html
http://www.environmentalscience.org/el-nino-la-nina-impact-environment

Finally, climate models are continously progressing and the simulation of important modes of climate variability has increased the overall confidence in the models’ representation of important climate processes.They can simulate the effect of El Niño and Niña effect, xtreme events, cyclones, cloud feedbacks, cryospheric feedbacks and others.

Further information: 

https://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf

Links;

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/jul/21/realistic-climate-models-accurately-predicted-global-warming
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/jul/21/realistic-climate-models-accurately-predicted-global-warming
http://my2050.decc.gov.uk/?shared=true&user=&percent=17&s=22021222221222

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.