Science Web Corner I.S.S.N.: 1579-1149

El rincón de la Ciencia         nº 46 (julio-2008)

Climate Change (rc-110-i)


A. Pérez González
(IES Torre Almirante. Algeciras, Cadiz)

English Translation: J. Cantos


This is a English version of the El cambio climático


INTRODUCTIÓN

On December 22nd, 2005, the General Assembly of the Organization of the United Nations (UN) declared the year 2008 as the International Year of the Planet Earth after a joint presentation of the International Union Geological Sciences (IUGS), the Organization of the United Nations Educational, Scientific and Cultural Organization (UNESCO) and other companies and groups of the Earth sciences worldwide collaborating with the United Nations Environment Programme (UNEP). The aim of the Year is to raise global and national awareness of the immense potential of Earth Sciences, in both politicians and public in general, as a contribution to create a safer, healthier and more prosperous society.

Their specific aims include that of determining non-human factors of climate change. Data are displayed on the table and the whole scientific community agrees. Climate change is a fact, what varies is the way of interpreting and discussing the causes that originate it.

In the study of climate change, we must consider matters from the most diverse fields of Science: Meteorology, Physics, Chemistry, Astronomy, Geography, Geology and Biology have much to say constituting this item a multidisciplinary field. The consequences of understanding or not fully understand climate change issues have deep influences on human society, having these points of view to be treated from very different points of view to the previous ones, such as the economic and the political ones.

EXPLANATION OF THE PHENOMENON

Explain what the climate is and its undergoing changes is not an easy task. To start, we should bear in mind that the definition of climate refers to the average state of the atmosphere over a long period of time. Therefore, the data in a single year are not enough to demonstrate the existence of climate change.
Likewise, variations in climate depend on a number of factors, for example, conditions of the atmosphere, surface water and groundwater, ice and snow covered areas, the mainland, including its diverse ecosystems and vegetation types, solar activity, changes in the  Earth´s orbit, volcanic eruptions, whose ash darken the atmosphere, or human activity which adds gases or particles into the atmosphere.

Otherwise, climate change is part of the history of the Earth. Throughout its 4,600 million years, our planet has undergone great climatic fluctuations, with alternating periods with warm weather and glacial one, sometimes abruptly from one situation to another. To produce these changes  a big change in temperature is not required. Thus, the average temperature difference between a cold time in the Earth, with large ice caps spread over the whole earth, and another as the present one is only  of about 5 ºC or 6 ºC. Hence we find the interest in the temperature of the atmosphere, as some seemingly small changes can involve major changes in ecosystems and climates and lifestyles of large areas of the Earth.

To understand the climate, scientists use powerful computers to perform mathematical models with which they try to take into account all of these factors, the relationships between them and the laws regulating their changes. Because of this complexity, the findings may be very different. There are other studies that talk about possible evolutions of our planet that would be traumatic for human species, although they are often contradictory. It has been said for example that climate change can prevent the next glaciation, or that in 500 million years there will not exist any life on the Earth.

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Current images of melting in the polar ice caps and glaciers

Notwithstanding, even if  what could happen is not exactly clear, there is some evidence that climate is changing, so there are some reasons to be on alert. The past decade has been the warmest in the last 500 years in Europe, as well as temperatures have reached unprecedented levels in Canada, United States
Hawaii, China, Russia and Alaska. In this sense, it is estimated that for the next 100 years there will be a global warming between 1.5 and 4.5 º C, and even up to 8 and 10 degrees in polar regions, moreover taking into account that since the industrial revolution the atmospheric temperature has risen 0.5 ° C. This change could produce, for example, that deserts became warmer, with serious consequences in the Middle East and Africa, where water is scarce. Furthermore, between one third and a half of all world glaciers could melt, reason for which millions of people might see their environments flooded by the rising waters.

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Pictures of the effects which the  increase of the level of Water and/ on Tsunami could cause on  seaside environments.

 

Scientists consider the so-called "greenhouse effect" as one of the main causes of temperature rise. The Earth experiences a natural effect that makes that its received energy,  goes back more slowly and it is "maintained" a longer time near the surface and thus the increase of  temperature continues. Thus, the average temperature on the Earth is about 15 ºC. Even if the atmosphere did not exist, it would be of about -18 ºC. It is called the greenhouse effect because of its similarity, because in fact, the physical action by which it is produced is totally different from what happens in the greenhouse plants. However sun rays do not penetrate so easily through some gases or other ones, so meanwhile oxygen and nitrogen are transparent to infra-red radiation, greenhouse gases are not. In the last century, the concentration of carbon dioxide and other greenhouse gases in the atmosphere, such as methane and dinitrogen oxide, has been growing steadily due mainly to human activity from the burning of large masses of vegetation to expand farmland, to the massive use of
fossil fuels like oil, coal or natural gas.

But most climatologists seem to worry about the amount of water that would arise as a consequence of the Greenhouse effect. The journal Nature published, coinciding with the première of the film "The Day After Tomorrow”, a study of British scientists whereby sea warming would achieve three grades before the end of the twenty-first century. Thaws will make, then, that sea level rises 7 metres. Respect to rainfall, scientists are not very precise. According to Javier Martín Vide, professor of Physical Geography at the University of Barcelona, "the expectation is that in the Mediterranean area there will be little rain but strong, two characteristics that we should avoid”.

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Gas emissions that cause the increase of the Greenhouse effect and what  could happen in the future if conditions which influence on sun radiation in the Earth changed.

While a large number of researchers share the view on the human dimension of climate change, others accuse the solar radiation, which would be influenced by the movement of our galaxy and whose retail presence would increase temperatures, that is to say, an astronomical factor. Because if it comes to happen that the influence of the Sun is in a lot of respects greater than the influence of everything else that humans can make (consumption of fossil fuels, energy costs for industry, etc.), a terrible future would be awaiting us as whatever it was saved, it would be just the same, because the effects of sun rays would be unable to be thwarted. The average temperature of the Sun on the Earth depends largely on the flow of the sun radiation that it receives. However, due to the fact that the contribution of that energy only varies over time,  it is not considered an important contribution to climate variability.

Variations in the solar magnetic field and therefore the emission of solar wind are also important because the interaction of the Earth's upper atmosphere with particles from the Sun can generate chemical reactions in one way or another, modifying the composition of air and clouds as well as their formation.  While the solar luminosity remains virtually constant over millions of years, it is not the same with the Earth´s orbit. This one varies periodically, making the average amount of radiation received by each hemisphere fluctuate over time, and these variations cause glacier and inter glacier pulses to some extent similar to long summers and winters. This is the case of the so called glacial and interglacial periods. There are three factors that contribute to change the orbital characteristics making the average of  insolation in both hemispheres change, although the flow of radiation does not fluctuate.  This is the precession of the equinoxes, the orbital eccentricity and obliquity of the orbit or the Earth's  axis tilt.

Catastrophic events that change the face of the Earth forever occur on unusual occasions. The last of such  catastrophic events happened 65 million years ago. These are the impacts of large meteorites. There is no doubt that these phenomena can cause a devastating effect on the climate by releasing large amounts of CO2, dust and ash into the atmosphere from the burning of large forested tracts. Likewise, such events would enhance the volcanic activity in certain regions. After a quite   powerful impact, the atmosphere would abruptly change, as well as the geological activity of the planet and, even its orbital characteristics.

The Earth has undergone many changes since its origins 4,600 million years ago. Continents were united 225 million years ago forming what is known as Pangea, and there was a universal ocean called Panthalassa. This provision led to increases in ocean currents and caused that the difference of temperature between the Equator and the Pole was much lower than today. Plate tectonics has separated continents and it has established the present geographical arrangement. The Atlantic Ocean has been making up for 200 million years. Continental drift is a very slow process, for that reason the position of  continents fixes the weather patterns over millions of years. There are two aspects to consider. On the one hand, the latitudes where the land mass is concentrated: if the masses are located in low-latitude, there will be few continental glaciers and in general less extreme temperatures. Likewise,
if continents are very fragmented, there will be fewer ocean currents, or sea ones, which are a climate regulating factor which acts as a moderator, diminishing temperatures in regions like Europe.

In the same way that the solar wind can affect climate directly, changes in the
 Earth's magnetic field can indirectly affect it, thus, according to its state, the particles emitted by the Sun are stopped or are not. It has been proved that in the past there had been polarity reversal and large variations in intensity, becoming almost cancelled at certain times. We also know that the magnetic poles, even if tending to be near of the geographic poles, have approached the Equator in some cases. These events had to affect, influence and will keep on guiding the way in which the solar wind reaches the atmosphere.

The National Geographic documentary titled "The day that the oceans boiled" argues that in the seabed there are enormous quantities of methane hydrates accumulated over the centuries, millennia. That methane comes from the decomposition of organic matter which is washed to the sea by rivers and there it sinks forming large deposits of methane hydrates in the deep ocean. Methane hydrates are very unstable in relation to temperature, and if temperature rises above a certain level, hydrates (which looks like an effervescent tablet) decompose and release methane gas, which rises to the surface as bubbles and then into the atmosphere (hence the title of the documentary "boiling oceans"). There are satellite photos where columns of gas are coming out of the ocean's surface, like a chimney. And once in the atmosphere, the greenhouse gas methane is much higher than the CO2.

This means that if temperatures continued to rise today, they would not always rise gradually, but at one point, when the critical temperature at which methane hydrates from the sea bottom decompose, exceeds, we will reach an inflection point, a point of no return, because the methane gas would rise to the atmosphere in large quantities, fact which would greatly increase the greenhouse effect, the temperature would go on rising, more methane hydrates would be decomposed and a kind of unstoppable and disastrous chain reaction would take place in the Earth's climate.  Or rather disastrous to humans and other living beings that inhabit the planet, because the change would be dramatic in a very short time, even perceptible in the life cycle of a human being (hurricanes, rising ocean levels and temperatures, extinctions, etc.).

If we take a look at the frequency with which hurricanes have shaken in recent years compared with the frequency of past decades, it is clear that the increase is very noticeable. That is an objective fact. And it happens that the formation of hurricanes is directly related to the temperature of the ocean surface.  That means that the temperature of the ocean itself has increased, and this is also an objective fact, but we still do not know if it will be a steady rise in progressive trend or just a temporary rise framed within a larger cycle of ups and downs.

MAJOR SCIENTIFIC POSITIONS ON THE CLIMATE CHANGES

There are three common scientific identified attitudes, each one with a public defender.

A) "Humanity is directed to an inevitable and almost immediate ecological disaster " by James Lovelock (One of the most famous and controversial scientists of the second half of the twentieth century. His theory is stated in the book 'The Revenge of Gaia ').

Lovelock says that the deterioration of the planet is irreversible, that the system is moving at a critical time from which it will take centuries to recover. He points out that human capacity to change this process happened 50 or 100 years ago and he compares the current time with the time that he lived in 1939, "when everyone knew a world war was going to start, but no one even acknowledged it”.
He declares that in less than a century, only 500 million humans will survive the change climate and they will all live in the Arctic. The Arctic ice cap and tropical forests will have disappeared and he announces an increase of eight degrees in temperature of the Earth in 70 years and he assures that it will remain that way for another 200,000 years.
As a workaround, he is committed to nuclear power as an essential energy to conserve our civilization, the only one capable of providing food, heat and electricity to the survivors of the climate catastrophe in their Arctic retirement.
 

B) "The world is moving toward its inevitable destruction, but there is still no cure for it. The human being has a maximum of 20 years to stop this process" by Al Gore, former U.S. vicepresident, consolidated politician who has changed the presidential race for the green one. His theory is displayed in the documentary "An inconvenient Truth '("An Inconvenient Truth")-Oscar-winning two, in the book of the same title as number one in sales according to the classification of The New York Times, and on the web www.climatecrisis.net .

Al Gore warns people with horrifying statistics: more than a million species could become extinct before 2050, that year there will not be any ice left in the Arctic, in just 25 years deaths consequence of climate change will double, rising to 300,000 people a year. His goal is not to panic but to raise awareness worldwide of people´s responsibility in the process. To this end, his film is the reconstruction of the speech that he constantly gives the world and whose effect he seeks to amplify with the new media.
As a solution, he argues that if we reduce emissions by between 60 and 80% in the next decades, we will stabilize the temperature increase to a maximum of two degrees. Thus, 10 simple gestures that can change the fate of the world: use light bulbs low-power, drive less and slower, recycle more, check tires, use
public transport, use less hot water, adjust the thermostat, plant a tree and unplug appliances.

C) "There is a scientifically demonstrable and man-made global warming, but we do not have enough data to predict the consequences in a complex system like the Earth" by Manuel Toharia, Climatologist and Director of the Museum of Arts and Sciences in Valencia. The book which sums up his philosophy is "Climate, global warming and the future of the planet."

Toharia finds that the planet is warming due to increased concentration of gases that cause the greenhouse effect, but he explains that we cannot predict the future with regard to climate.
He insists that we do not know the ultimate consequences of this process and he criticizes those who he nicknames
"Environmental fundamentalists" and who make predictions without any scientific basis.
He explains that climate change is a constant in the history of the Earth, which has undergone a lot of changes in its lengthy evolution and has regulated later, and certainly he doubst the power of man to decide on the future of the planet. He renounces that the science of climatology works with time periods of at least 30 years, so the higher temperatures experienced so far are connected at the moment to "time" (or to the weather) and not to climate.

He disowns doomsday gurus ("Who cares what will happen in a century when millions of humans are starving and dying with thirst at the moment?”). Besides, he denounces the futuristic hypocrisy of climate crisis. ( What do Bangladesh population care if the country could be flooded in one hundred years if they are dying nowadays?)

As a solution, he thinks there is no alternative to the current energy production through fossil fuels (causing maximum carbon dioxide emissions) and that although it existed, it woud be more expensive, and it would not be useful either. He maintains that individual attitude is a great weapon against global warming and he considers that the problem would decrease if countries´citizens did not waste resources.

FORECASTS AND POSSIBLE SOLUTIONS

There are five major immediate risks facing the world as a result of climate change.

 •Decrease in agricultural productivity, especially in Asia and Africa.

•Increasing water scarcity.

•Increase of the number of extreme weather events.

•Widespread deterioration of ecosystems.

•Increased incidence of diseases such as malaria or dengue.

This is a global problem, and solutions must be taken by all countries. The measures to be taken are very diverse, but largely collide with the industrial and economic development model proposed today: Increase efficiency in the recycling of materials and replace polluting materials and processes by causing fewer emissions of greenhouse gases, change the life style based on energy waste and transportation habits, build houses and buildings that use energy with more efficience, establish appropriate forestry policies to halt deforestation and regenerate forests, properly assist countries with less developed economies, stimulate research and development to make available new technologies, etc..

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Varias imágenes de como está influyendo actualmente el cambio climático, con zonas con largos periodos de sequía, otras zonas con abundantes lluvias y empantanadas continuamente, y el aumento del número de huracanes y tormentas tropicales
 

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