Causes of Global Warming
January 13, 2009
Existence and significance of the consensus
Proponents of the existence of
a consensus about human responsibility in global warming
based on the position of several scientific institutions and
the number of climate scientists involved in the analysis of
the IPCC. This
consensus has sometimes been questioned by politicians,
particularly the United States. But
according to a study published in the journal Science by
a historian of science, Naomi Oreske, analysis of 928
abstracts of scientific articles selected from a database
using the keywords “climate
change” and
published between 1993 and 2003 shows that none of them
challenged the consensus established by the IPCC. In 2005, a
British anthropologist Benny Peiser challenged those results
in an against-study. He
said finding a number of articles denying the consensus. Peiser’s
work has been subjected himself to criticism, such as not
being limited to articles reviewed by committees of reading
or to have improperly classified a number of articles among
those rejecting the consensus. In
2006, Peiser admitted that the vast majority of
climatologists is agreed with the argument that global
warming is caused by human action but that was far from
unanimous.
In addition, the United States,
a petition was signed by more than 31,000 graduates from all
scientific disciplines (more than 500 in atmospheric science
and climatology and 9,000 doctors in all disciplines, calling
into question the argument that the emission of greenhouse
gases would cause a “catastrophic warming. The former
president of the National Academy of Sciences, Frederick
Seitz has supported this petition. Critics
of the petition a point considered misleading which give the
impression to potential signatories of an official
publication of the National Academy of Science. The
specialist in atmospheric chemistry Raymond Pierrehumbert
also denounces the fact that the petition was accompanied by
an article full of half truths presented as a takeover of an
article published in a scientific journal. Finally,
some are questioning the number of signatures stressing the
impossibility of verification and a few oddities in the
list.
In 2008 a report was published
NIPCC of (Nongovernmental International Panel on Climate
Change), written by Professor Fred Singer, with the
collaboration of 24 scientists at the highest level. This
report, including a French translation was published, says
that this is the kind that changes the climate, not humans,
and makes a severe criticism of the IPCC and its methods.
Character exceptional
warming
The climate variations knows
fair and a number of observers and scientists noted that the
current warming is part of these variations.
Thus, a recent warming, the
medieval climate optimum, took place in the Middle Ages,
followed by a cooling period, the little ice age, leading to
major changes in the extent of glaciers. It
is believed that they were shorter in 1200 BC today, before
rising raw ice between the fourteenth and the end of the
nineteenth. Some
walkways of ancient Rome are still covered by glaciers.
At the optimum medieval culture
of the vine has grown in England. In
addition, the Vikings have settled in the same period in
Greenland, the name of this country, meaning “green
countries in Danish.
In contrast, the
arguments for not overestimate global warming based on the
fact that on the one hand, the vines grow still in Britain,
other than the name of Greenland has been chosen by explorer
Erik the Red in order to attract settlers in 5000 and that
their settlements were limited to the south of the island.
The Histoire_du_Groenland shows that the Vikings were very
poorly adapted to their environment unlike Inuit who
replaced. The
Vikings lived mainly on agriculture and livestock.
Criticism of
the hypothesis of an increase in greenhouse
-
The impact of human
activity on global warming is illustrated by a
comparison between the temperatures of weekdays and
weekends in 2003, a U.S. study conducted by Forster on
30 years and more than 1,000 stations shows that the
temperature of the weekend, 0.5 ° C on average, are
stronger than other days of the week. This
difference between weekdays and weekends is correlated
with the weekly cycle of human activity (high and low
this week on the weekend).
-
Another argument made by
scientists who doubt that human activity is responsible
for the warming of the Earth is that the same phenomenon
is also observed on Mars, and there is even up to four
times faster , but there is no human activity on Mars,
which may lead to believe that the cause is the cause of
two observations. This
hypothesis is however rejected by climatologists support
the hypothesis that man, according to them, the causes
of Mars are warming to this planet, and in no way linked
to an external source, including solar, which would be
shared with the Earth. Of
warming would also measured 4 on other bodies in the
solar system (Neptune, Jupiter, Triton, Pluto)
For Neptune, the explanation
comes from its position on its orbit now ( “Summer”
Neptunien) Explanation similar Triton. Jupiter
is in a period where its giant storms merge, leading to an
inability of the planet to more evenly distribute its
temperature.Observations on the warming of Pluto are 2,
separated by 14 years, and therefore does not draw any
conclusion.
-
Since 2002, the AQUA
satellite of NASA makes
accurate measurements of the cycle of atmospheric water
vapor, the main greenhouse gas, clouds and precipitation
in order to better understand the feedbacks in the
evolution of atmospheric temperature. In June 2008, Dr. Roy
Spencer (scientist), after
analyzing data, concludes that, contrary to models used
by various research centers, the atmospheric water makes
a strong negative
feedback to
the greenhouse effect and that the assessment of global
warming should be strongly reduced.
-
Beginning in 2008, Ferenc
Miskolczi, Hungarian physicist, publishes an article in
a scientific journal of Hungary, which presents a new
model of the “greenhouse effect confined in an
atmosphere over semi-transparent.” His
study concludes that the influence of greenhouse gases
on global warming is overstated by the IPCC and
to look for other causes global warming.
Assumption of
fluctuations in solar activity
Solar activity since the year 900, as measured by the change in
amount of carbon 14 compared to the current in the woods (there
were more solar activity and there was less carbon 14 produced
in the atmosphere and the wood of the time, because the solar
wind becomes cosmic rays that produce carbon-14)
-
The Maunder Minimum is a
shortfall in the number of sunspots between 1645 and
1715. A century after the Maunder Minimum occurred
minimum Dalton. Notwithstanding these minimum periods is
very clearly a variation in the number of sunspots, the
next solar cycle of about 11 years.
During the Little Ice Age the Maunder Minimum is a period,
roughly between 1645 and 1715 during which the number of
sunspots, and hence the magnetic field of the Sun and all forms
of activity that follows, was significantly lower today.
In 1997, Danish physicists Eigil Friis-Christensen and Svensmark
announce Hensik have established a correlation between past
changes in climate, cloud cover and solar activity. They
believe a strong solar activity would lead to a decrease in the
flow of cosmic rays of galactic origin, reducing the ionization
of the atmosphere and causing a lesser training nuclear freezing
and condensation. Cloud
cover would be reduced, reducing the albedo of
the planet and thus warming.
This thesis is given in March 2007 in the movie of television
producer Martin
Durkin,which collects in the film (subtitled in French)
The Great Global Warming Swindle (The great scam of global
warming). The film cites a study from 2005 Ján Veizer
(Ottawa-Carleton Geoscience Center, University of Ottawa),
showing the correlation at different time scales, and the
influences from other types of cosmic rays with including an
influence on the evaporation of water and cloud cover. The list
of 20 persons (18 researchers) is available in the article The
Great Global Warming Swindle (Contributors to the program). For
them, thanks to studies of correlations, fluctuations in solar
radiation have a much greater influence on the change in climate
that releases of CO2by the man.
This film has received strong criticism from the Royal Society
and the Met Office, who published a case against in-8 points.
Arguments against
Shortly after the presentation of the theory of Friis-Christensen
and Svensmark, the American Paul Damon and Danish Peter Laut
said to have found errors in the data cited to support their
hypothesis. In
addition, a reduction of cloud albedo decrease certainly, but
also decreases the impact of the greenhouse effect and it is
unclear whether the final results in a warming or cooling of the
atmosphere. Finally,
the role of cosmic rays in the creation of condensation nuclei
is discussed, particularly in the lower layers of the atmosphere
where aerosols appear to play a dominant role. In
addition, Eigil Friis-Christensen said in 2002 that the
correlation climate-solar activity not occurring since the
1980s.
In 2001, Peter Stott and other researchers at the Hadley Center
of the United Kingdom have published an article on the model of
numerical simulation the most comprehensive ever done on the twentieth century.
Their study included both officers
natural forcing (solar
variations and volcanic emissions) and anthropogenic
forcing(greenhouse gases and sulphate aerosol form). Like
Thejll and Lassen, they found that natural factors explaining a
gradual warming until 1960, followed by a return to temperatures
close to those of the late nineteenth century,
in agreement with the gradual change solar forcing during the twentieth
century and the volcanic activity in recent decades. These
factors alone could not explain the warming of recent decades.
Similarly, the anthropogenic forcing alone could not explain the
warming of the 1910-1945 period, but may be necessary to
simulate the warming since 1976. However, combining all these
factors, the team Stott was able to accurately simulate changes
in global temperatures during the twentieth
century. They predicted that the continuous emission of
greenhouse gases cause temperature rises of the future “at a
pace similar to that observed in recent decades.” A graph of
the relationship between the natural factors and contributing to
anthropogenic climate change is contained in the reportClimate
Change 2001: The Scientific Basis of
the IPCC.
In the May 6 edition of 2000 of U.S. magazine New
Scientist, Lassen
and astrophysicist Peter Thejll supplementing the 1991 study
with new data, concluded that although the solar cycle can
explain about half of the increase in temperature observed since
1900, he could not in any way explain the increase of 0.4 ° C
since 1980.
In 1991, Knud Lassen of the Danish Meteorological Institute in
Copenhagen and his colleague Eigil Friis-Christensen [58] have
found a strong correlation between the length of the solar cycle
and changes in temperature in the northern hemisphere.
Initially, they had included sunspots and temperature
measurements taken between 1861 and 1989, but later noticed that
records dating back four centuries confirmed their discovery.
This correlation could explain 80% of temperature changes during
the period. This study, and the graphics were subsequently
challenged, as based on incorrect values. Sallie Baliunas, an
astronomer Center for Astrophysics at Harvard-Smithsonian
Institution, was one of the most ardent supporters of the theory
that solar activity “may explain the changes of climate in the
last 300 years, particularly current global warming. “ However,
the data show that the correlation between temperature and solar
activity is no longer valid for the last thirty years, it
remained roughly constant.
In 2007, the fourth report of the IPCC estimates that the
radiative forcing due to greenhouse gases produced by human
activity is ten times greater than that due to solar radiation.
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