CLIMATE CHANGE AT GLOBAL
LEVEL
INDEX
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The first studies: climate changes
Albedo
Volcanoes and volcanic eruptions
Ocean currents and Co2
Change in temperature and
greenhouse gases over time
Permafrost
Water vapour and clouds
Solar variation
Displacement of the tropics
The first studies: the climate
changes
It is argued that the current change of the climate is provocated by
careless actions of people.
The Earth has the ability to react to this change but in a very long time
so, for this reason, people risk to self-destruct.
Scientists believe that:
⋆ The average temperature of Earth’s atmosphere is increasing;
⋆ The concentration of greenhouse gases in the atmosphere is
increasing;
⋆ There is a correlation between the increase in temperature and the
increase in the concentration of greenhouse gases in the atmosphere;
⋆ The increased concentration of greenhouse gases in the atmosphere
is due to anthropogenic emissions.
Other scientists suppose that there are effects due to global warming:
⋆
Reducing volume of glaciers: since the end of the little ice age, glaciers of
mountain ranges are in sharp decline over the whole earth.
⋆
Oceans are warmer and acids : the ocean surface is 30% more acidic than it was
in 1800, and 50% of this change has come from the increament of CO2 in the
atmosphere, endangering coral reefs and various species of plankton that
form the base of the food chain of the sea.
⋆
Average temperature difference between day and night is easing: another
change concerns the thermal shock that occurs between the day and the night,
and that turns out to be stronger than in previous years.
⋆
Animals are shifting their habitat poleward: climate change means also changes
in the life of animals which make a considerable effort to adapt, hence the pole
shift.
⋆
Plants bloom days or weeks earlier than in the past: the percentage of
endangered species compared to those analyzed is 69%, while compared to the
known ones is 2%.
Factors that affect the climate
The climate changes and this depends on various factors:
• the albedo;
• Volcanoes and volcanic eruptions;
• the absorption of Co2 and oceans currents;
• changes of the temperature and greenhouses gases over
time;
• the permafrost;
• water vapor and clouds;
• the variation of solar activity;
• the displacement of the tropics.
Albedo
The albedo is the ratio between the amount of
solar energy reflected from the Earth-atmosphere
system and the total energy coming into the
system.
The albedo of the Earth-atmosphere is 0,35.
A completely white surface has
an albedo of 1, because it
reflects all the light.
A completely black surface
has an albedo of 0 because it
absorbs solar rays.
Therefore a surface without
snow or ice absorbs more
radiation.
Consequences of the albedo
One of the more evident consequences is the melting of the ice, that,
being white, reflects a very effective radiation, while the water and
the soil , being darker, reflects less.
The more ice melts because of the increment in temperature, the
more soil and water become widespread, and the greater the
absorption of heat by the planet is.
Volcanos and volcanic eruptions
A volcano is a geologic, complicated rocky structure, which is generated in the
Earth’s crust by the ascent of the magma formed below or in the Earth’s crust.
A volcanic eruption is the leakage of magma and other gaseous materials in the
Earth’s surface from the mantle or the crust.
Typically a volcanic eruption happens either in the main crater of a volcano or in
the minor craters of the volcano.
The classification is based on the characteristics of magma and on the type of
eruption. Considering the type and the power of the eruptive activity of a
volcano we have:
• Volcanos with Hawaiian eruption;
⋆ Volcanos with Icelandic eruption;
⋆ Volcanos with Surtsey eruption;
⋆ Volcanos with Strombolian eruption;
⋆ Volcanos with volcanic eruption;
⋆ Volcanos with Vesuvian eruption;
⋆ Volcanos with Plinian and Peleana eruption.
Consequences of the vulcanic
activities
⋆ Volcanic eruptions are capable of triggering climate change in a
short time with an efficiency that is unmatched in nature.
⋆ In a few months, the atmospheric temperature of the Earth can
drop, causing droughts, floods and cold weather. (TRADURRE)
Co2 ABSOPRTION AND
OCEANIC CURRENTS
Not all of the carbon dioxide we produce stays in the atmosphere, oceans
absorb 1/3 and ¼ of Co2 every year.
This gas dissolves in salty water, creating carbonic acid .
Since the concentration of atmospheric Co2 keeps increasing, oceans absorb
more and more Co2, thus producing more and more carbonic acid. This acid
is changing the chemical balance of the oceans: the process is known as
“ocean acidification”.
Thermohaline circulation: this is the global oceanic circulation due to the
variation of density of the water masses.
A oceanic current is a mass of sea water in movement with respect to the
surrounding water and from which it is different in density, salinity,
temperature or colour.
Trends in temperature and
greenhouse gases during time
The greenhouse gases present in the atmosphere are about 30 and they can
capture heat. The water vapour is the most efficient gas in the control of the
air temperature of the Earth’s surface Greenhouse gases are necessary to trap
the energy irradiated by surface of the Earth which, otherwise, would be
extremely cold. This process limits the flux of energy going outside : in this
way, the heat which remains in the atmosphere causes atmospheric warming
from the inside.
The substances present in the air behave differently towards the visible
radiations and the infrared radiations
It was discovered that some elements, like oxygen and nitrogen, are
transparent, while others, like carbon dioxide and water vapour, are only
partially so. The molecules of water vapour, carbon dioxide and ozone absorb
the heat the most.
I risultati dimostrarono che la temperatura terrestre sarebbe
aumentata di fronte ad un incremento dei gas serra.
Il gas su cui è concentrata la massima attenzione è la CO2 immessa
nell’atmosfera a causa del consumo dei combustibili fossili per le
attività umane. Oltre all’anidride carbonica, vi sono altri gas serra la
cui quantità si è accresciuta in seguito all’emissione antropiche. La
concentrazione del metano è più che raddoppiata dall’epoca
preindustriale ad oggi.
The dates of andature trend of the Earth’s athmosphere
…si ricavavano dall’accrescimento degli anelli degli alberi o dai rapporti
fra gli isotopi da vari elementi nei ghiacciai dell’ Antartide e della
Groenlandia, nei coralli e nei sedimenti lacustri. Dall’ insieme di
questi dati si ricava la temperatura media globale; questi dati sono
essenziali per sconfiggere il “riscaldamento del pianeta”.
La ricostruzione delle temperature del passato in base a dati indiretti è
un percorso molto difficile. Per esempio, gli anelli di accrescimento
degli alberi riflettono non solo gli effetti delle variazioni di
temperatura, ma anche delle eventuali variazioni cospicue della
piovosità; inoltre, la crescita degli anelli può variare a seconda dell’età
della pianta (più un albero è vecchio più anelli piccoli produce) .
Permafrost
In areas in high latitudes, where temperatures are very low, the soil is
called permafrost, namely "permanently frozen." It is divided into
several states which can be up to a hundred meter deep. Permafrost
was formed by the last glaciation and permafrost is divided into:
saturated and supersaturated soil. Due to the increment in
temperature, permafrost is starting to melt permanently.
Some plants use to the melting and they don’t decompose but with permafrost
remain intact for thousands of years and this has made a huge permafrost
carbon sink. With the increase of temperature, however, the planet warms
and may start to emit greenhouse gases that can amplify the effects of global
warming.
Clouds
The clouds occupy about half the atmospheric surface and this have a
significant effect on the budget radioactive terrestrial based on their
thickness. According to the Iris effect a warmer Earth would produce
more water vapor in order to protect the Earth from the sun's rays
limiting warming. But according to another hypothesis the clouds
should trap heat and strengthen the heating. But the cloud cover
increase the green effect.
Variazione dell’attività solare
The sun, our star, gives us heat, light and energy. It is a great nuclear
power and hydrogen presents sudden changes in its active phase. In
the past we had several epochal climate change going from a tropical
climate in the Jurassic one in the Quaternary Ice Age. This is caused
by a change important energy of the Sun.
The most important solar variations recorded in recent years are:
-Minimum Oort;
-Thermal Maximum medieval;
-Minimum Wolf;
-Minimum Spoerer;
-Maunder minimum;
-Dalton minimum.
The displacement of the tropics
According to a survey the displacement of the tropics coincides with
the rise in temperature of 0.8 degrees Celsius. Because the masses of
warm tropical air-move away from the equator. The Hadley cells are a
type of convective circulation and precipitation determine both the
equatorial and subtropical drought.