What is the climate change? What are its consequences? Why do we have climate change? In the next essay we will try to give the answer of these questions and explain it. Climate change is a long-term change in the climate of some region or across the planet. This change is related with average weather, precipitation, tornados and more. The climate change is not only changes in the average weather, is also considered climate change if the weather average remain but the variability of climate change.
Climate changes appear when the climate of some area is modified between 2 periods of time. This changes happens when something change the total quantity of the sun's energy for the earth surface and atmosphere or when something change the quantity of heat energy form the earth's surface and atmosphere that goes to space during a long time.
Changes in the quantities of solar and heat energy can produce two kinds of changes in the weather conditions, in average weather conditions and changes of the distribution of events around that average weather. Those changes can be caused by natural conditions as volcanic eruptions, changes in the sun energy and can be caused by humans, by releasing greenhouse gases, aerosols…
One and the other, human and natural factors that cause the climate change are called climate forcing, because they force climate to change.1
Greenhouse effect
The "greenhouse effect" is a natural system that regulates the temperature on the Earth. Fourier said that some gases were holding back heat from the Earth, just like a glasses in a greenhouses. Our atmosphere keeps the sun´s heat near the surface of the Earth by keeping some properties of "greenhouse gases" as we can see in the first picture.
Earth is heated by the sun the biggest part of the sun energy goes through the atmosphere, warming up the surface, oceans and atmosphere. But, in order to maintain the atmosphere in balance, the Earth also emits heat energy to the space as infrared radiation.
As this energy radiates to the space, most of it stays in the clouds and molecules of greenhouse gases in the atmosphere. These re-radiates the energy in every single direction, some back to the Earth and some to upward again, where other molecules can absorb them again. This process is repeated until the energy gets out of the atmosphere to the space.
Thanks to the most part of the energy which has been recycled in his way down, surface of the Earth become much hotter than if the greenhouse gases were absent from the atmosphere.
All this process is known as the greenhouse effect. If we did not have the greenhouse gases, the planet average temperature will descend from around 15°C to -20°C, an average of 35°C colder.
During the last ten thousand years, the quantities of greenhouses in the atmosphere have been remaining stable. But few centuries ago, and much more the last century, they have increased a lot due to the demand of energy because of the industrialization, the rising population all over the world and the change of the use of the land.2
Causes of climate change
Natural causes
Solar cycles
The average temperature on Earth depends on the flow of solar radiation that Earth receives. However, because that contribution of energy varies only slightly in time, it is not considered to be an important contribution to the short-term climate variability. This happens because the Sun is star in main sequence phase, which is very stable. The radiation flux is also the motor of the atmospheric phenomena and which provides the necessary energy to the atmosphere so that they occur.
On the other side, long-terms variation become noticeable as the sun increases its luminosity at a rate of 10% every 1000 million years. Because of this phenomenon in the early Earth that supported the birth of life 3800 million years ago, the brightness of the sun was 70% of the current.
Orbital cycles
While the solar luminosity remains practically constant over millions of years, is does not happen the same with the Earth's orbit. This oscillates periodically, making the average amount of radiation received by each hemisphere fluctuate over time, and these changes cause glaciers pulsation mode summer and long winters. These are called glacial and interglacial periods. These factors contribute to changes orbital characteristics, making the average insolation in both hemispheres vary. This is the precession of equinoxes, the orbital eccentricity and obliquity of the orbit.
Volcanic eruptions
Volcanic eruption can produce big amounts of sulphates and aerosols and inject them to the stratosphere, reducing the sun radiation in the Earth surface and cooling the surface up to 0.5°C. Some scientist says that part of the fluctuation in the temperatures in the last century was produced by volcanic eruptions.
Topography changes
Changes in land and ocean topography, consequence of geological process, influence the climate by the absorption of solar radiation and impeding oceanic circulation.3
Human causes: Greenhouse gases
The world population practices helps to the climate change by producing changes in the Earth's atmosphere with greenhouse gases and aerosols as the most important. The one that contributes with more quantities of carbon dioxide released to the atmosphere comes from the burning of fossil fuels.
Greenhouse gases and aerosols contribute to the climate change with modification in the incoming solar radiation and outgoing infrared radiation. The modification atmospheric properties produce changes in the Earth's climate. As we can observe in the first graph, since the industrialization the effect of human activities in the climate change has been a bad influence. The human influence over the climatic change is much bigger that the one because of natural causes.
Carbon dioxide
Has raise from its use in fossil fuel for cars and manufacture of cement and plastic products. Deforestation release carbon dioxide and reduces the quantity of plants to absorb it.
Methane
Methane has raise as a result of human agricultural activities and natural gas distribution. This gas is not currently raising because its rates has decreased in the last years.
Nitrous oxide
It is emitted by the same two activities than the carbon dioxide and methane, by fossil fuel burning and agricultural activities such as fertilizer.
Halocarbon gas
This gas increased at first with human activities, the most important of them was as refrigeration agents and industrial processes. Due to international regulation in the last year this gas has decreased. Halocarbon release by human detstroy ozone and have caused the ozone hole over Antarctica.
Ozone
It is produce and destroyed by chemical reactions in the atmosphere. Human has raised ozone by the release of gases such as carbon monoxide which chemically react to produce ozone.
Water vapor
Is the most abundant greenhouse gas in the atmosphere, but humans only have a small influence in it with CH4 emission because it goes to the stratosphere and its destruction produce small quantities of water vapor.
Aerosols
Human activities such as industrial process increased dust in the atmosphere. Aerosols include mineral dust from the surface, sea salt and biogenic emissions from the land and oceans.4
Climate change effects
Oceans levels are rising due to the increase on the temperatures, as result of the melting ice caps and the expansion of the oceans. This could have many impacts as beach erosion or intrusion of salt water by the rivers in other ecosystems. Warming oceans will change the type and population of the oceans.
If the warm atmosphere increases, there will be more energy with faster cycles of rains and snow evaporation and transpiration, and more variability in weather with an increase in floods and droughts. All this will threat the agricultural and human health.
A boost in the emission of greenhouse gases change the carbon dioxide and other gases cycle affecting the interaction between plants and the atmosphere. This will affect the agriculture, forest and ecosystems. Warmer climates will let agricultural crops to grown in places where they cannot grown now. Some species could have competitive advantages leading others species to disappear.
As temperature and precipitation varies, some species will change their habitats and other ones will disappear. Some species will become unable to adapt and go northern or southern while other one would adapt. Changes in climate have the ability to expand species such weeds and mosquitoes.
If plant and animals species will experience changes will affect us directly in the production of goods or services as the purification of air and water, creation of fertile soils and control of floods and drought.5
Conclusion
In conclusion, the climate change is an important issue that affects everyone all over the Earth, human and not human.
With the start of the industrialization we started emitting more gases that the quantity than Earth and atmosphere can recycle. This will lead the world weather and climate into many changes that will affect us directly, will extinguish species and will change the Earth that we have always known.
There are already policies trying to decrease the contamination but it does not mean to be effective in a short time period.
Annexes
Picture 1
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Graphic 1
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