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

CARBON CYCLE

The carbon cycle is the circulation and transformation of carbon back and forth between living things and the environment. Carbon compounds are present in living things like plants and animals and in nonliving things like rocks and soil.

The amount of carbon on the earth and in Earth's atmosphere is fixed, but that fixed amount of carbon is dynamic, always changing into different carbon compounds and moving between living and nonliving things.

Carbon is released to the atmosphere from what are called "carbon sources" and stored in plants, animals, rocks, and water in what are called "carbon sinks."

There are many carbon sources like these;
Plants.
Through photosynthesis plants take carbon dioxide out of the atmosphere and release oxygen.The carbon dioxide is converted into carbon compounds that make up the body of the plant, which are stored in both the parts of the plants like shoots, leaves and roots.

Animals.
Animals eat the plants, breath in the oxygen, and exhale carbon dioxide. The carbon dioxide created by animals is then available for plants to use in photosynthesis. Carbon stored in plants that are not eaten by animals eventually decomposes after the plants die, and is either released into the atmosphere or stored in the soil.

Geologic processes.
Large quantities of carbon can be released to the atmosphere through geologic processes like volcanic eruptions and other natural changes that destabilize carbon sinks. For example, increasing temperatures can cause carbon dioxide to be released from the ocean.

While a portion of the total amount of carbon present on the earth runs through the carbon cycle relatively quickly, another portion of the carbon is caught up in long-lived and stable carbon sinks.

In Earth’s past, the carbon cycle has changed in response to climate change. Variations in Earth’s orbit alter the amount of energy Earth receives from the Sun and leads to a cycle of ice ages and warm periods like Earth’s current climate. Today, changes in the carbon cycle are happening because of people. We perturb the carbon cycle by burning fossil fuels and clearing land. By burning coal, oil, and natural gas, we accelerate the process, releasing vast amounts of carbon (carbon that took millions of years to accumulate) into the atmosphere every year.

Today we can obtain the data of amount of emissions from the World Bank web site. (http://data.worldbank.org/indicator/EN.ATM.CO2E.PC/countries/CN-GB-US-ES?display=graph)

CO2 emissions (kt)

 

CO2 emissions (metric tons per capita)

These graphics show that China is the the largest producer of CO2 and USA is the greatest producer per capita. However, we can observe that the amount of emissions per capita in some counties have steadily declined since 2007, excepting China.

Since the beginning of the Industrial Revolution, when people first started burning fossil fuels, carbon dioxide concentrations in the atmosphere have risen from about 280 parts per million to 387 parts per million.
 
Nowadays human activity has contributed to an atmospheric concentration of carbon dioxide not seen since the Pliocene epoch between 2.6 and 5.3 million years ago.

Sources:
http://www.esrl.noaa.gov/gmd/ccgg/trends/#mlo_full
http://earthobservatory.nasa.gov/Features/CarbonCycle/

PLIOCENE vs TODAY

On May 9, 2013, carbon dioxide levels in the atmosphere reached the level of 400 parts per million (ppm). The last time the Earth experienced this level of carbon dioxide was in the Pliocene about three to five million years ago. Investigate what the temperatures were during this time period and compare them to today. What could explain the changes?


The last time atmospheric CO2 was at 400ppm, humans didn't exist. It was during the ancient Pliocene era, tree million years ago. If we compare the temperatures in that periode with the tempertatures today, we can observe great diferences:

• In the Piocene the global average temperatures were 3 to 4 ºC warmer than today and the polar temperatures were 10ºC warmer too.
• In the Pliocene the Artic was ice free and the sea level was between 5 and 40 meters higher.

However, the most important diference is that in the Pliocene a higher concentration of CO2 would have been entirely down to natural earth processes. Nowadays, the increase of CO2 levels has been happening much more rapidly today than it did during que Pliocene epoch because of the industrialization, the human activities, burning fosil fuels and other process have changed the amount of greenhouse gases emitted into the atmosphere. Therefore we will progressively continue see climate changes over the next years.



Sources:

http://www.esrl.noaa.gov/gmd/ccgg/trends/weekly.html
https://en.wikipedia.org/wiki/Pliocene
https://scripps.ucsd.edu/programs/keelingcurve/2013/12/03/what-does-400-ppm-look-like/
http://www.skepticalscience.com/pliocene-snapshot.html

BLANKET EARTH

I enjoyed this article from NASA, it explains breafly what are the causes of the current global warming.

NASA’s article A blanket around the Earth

Greenhouse gases act as a thermal blanket for the Earth. Most of them are surrounding us, for example methane is a gas produced by human activities like agriculture, carbon dioxide is associated to industrial activities and burning fossil fuels, nitrous oxide is a gas produced by soil cultivations practices, CFC's are used in industrial applications but the most abundant greenhouse gas is water vapour that has a great impact in the Earth's atmosphere warm but it also acts like a feedback mechanism to the climate which will be explained later.

 

The globalisation is a fact and not only do greenhouse gases cause a harmful effect  but also the human activities contribute to warm the planet. The industrial activities have raised atmospheric dioxide level during the last 250 years.

Finally, It's reasonable to assume that the sun's energy can cause the climate change but several evidences show that since 1750 the amount of energy coming from the sun remained constant and if the activity of the sun causes the warming, then we would expect to see warmer temperatures in all layers of the atmosphere and that is not happening.

 

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.