(Left)
Illustration of a synapse in the brain connecting two neurons. (Right)
Schematic of artificial synapse (ENODe), which functions as a
transistor. It consists of two thin, flexible polymer films (black) with
source, drain, and gate terminals, connected by an electrolyte of salty
water that permits ions to cross. A voltage pulse applied to the
“presynaptic” layer (top) alters the level of oxidation in the
“postsynaptic layer” (bottom), triggering current flow between source
and drain. (credit: Thomas Splettstoesser/CC and Yoeri van de Burgt et
al./Nature Materials)
Stanford University and Sandia National Laboratories researchers have developed an organic artificial synapse based on a new memristor (resistive memory device) design that mimics the way synapses
in the brain learn. The new artificial synapse could lead to computers
that better recreate the way the human brain processes information. It
could also one day directly interface with the human brain.
The new artificial synapse is an electrochemical neuromorphic organic
device (dubbed “ENODe”) — a mixed ionic/electronic design that is
fundamentally different from existing and other proposed resistive
memory devices, which are limited by noise, required high write voltage,
and other factors*, the researchers note in a paper published online
Feb. 20 in Nature Materials.
Like a neural path in a brain being reinforced through learning, the
artificial synapse is programmed by discharging and recharging it
repeatedly. Through this training, the researchers have been able to
predict within 1 percent of uncertainly what voltage will be required to
get the synapse to a specific electrical state and, once there, remain
at that state.
“The working mechanism of ENODes is reminiscent of that of natural
synapses, where neurotransmitters diffuse through the cleft, inducing
depolarization due to ion penetration in the postsynaptic neuron,” the
researchers explain in the paper. “In contrast, other memristive devices
switch by melting materials at relatively high temperatures (PCMs) or
by voltage-induced breakdown/filament formation and ion diffusion in
dense oxide layers (FFMOs).”
The ENODe achieves significant energy savings** in two ways:
Unlike a conventional computer, where you save your work to the hard
drive before you turn it off, the artificial synapse can recall its
programming without any additional actions or parts. Traditional
computing requires separately processing information and then storing it
into memory. Here, the processing creates the memory.
When we learn, electrical signals are sent between
neurons in our brain. The most energy is needed the first time a synapse
is traversed. Every time afterward, the connection requires less
energy. This is how synapses efficiently facilitate both learning
something new and remembering what we’ve learned. The artificial
synapse, unlike most other versions of brain-like computing, also
fulfills these two tasks simultaneously, and does so with substantial
energy savings.
“More and more, the kinds of tasks that we expect our computing
devices to do require computing that mimics the brain because using
traditional computing to perform these tasks is becoming really power
hungry,” said A. Alec Talin, distinguished member of technical staff at
Sandia National Laboratories in Livermore, California, and co-senior
author of the paper. “We’ve demonstrated a device that’s ideal for
running these type of algorithms and that consumes a lot less power.”
A future brain-like computer with 500 states
Only one artificial synapse has been produced so far, but researchers
at Sandia used 15,000 measurements to simulate how an array of them
would work in a neural network. They tested the simulated network’s
ability to recognize handwriting of digits 0 through 9. Tested on three
datasets, the simulated array was able to identify the handwritten
digits with an accuracy between 93 to 97 percent.
This artificial synapse may one day be part of a brain-like computer,
which could be especially useful for processing visual and auditory
signals, as in voice-controlled interfaces and driverless cars, but
without energy-consuming computer hardware.
This device is also well suited for the kind of signal identification
and classification that traditional computers struggle to perform.
Whereas digital transistors can be in only two states, such as 0 and 1,
the researchers successfully programmed 500 states in the artificial
synapse, which is useful for neuron-type computation models. In
switching from one state to another they used about one-tenth as much
energy as a state-of-the-art computing system needs to move data from
the processing unit to the memory.
However, this is still about 10,000 times as much energy as the
minimum a biological synapse needs in order to fire**. The researchers
hope to attain neuron-level energy efficiency once they test the
artificial synapse in smaller devices.
Linking to live organic neurons
This new artificial synapse may one day be part of a brain-like
computer, which could be especially beneficial for computing that works
with visual and auditory signals. Examples of this are seen in
voice-controlled interfaces and driverless cars. Past efforts in this
field have produced high-performance neural networks supported by
artificially intelligent algorithms but these depend on energy-consuming
traditional computer hardware.
Every part of the device is made of inexpensive organic materials.
These aren’t found in nature but they are largely composed of hydrogen
and carbon and are compatible with the brain’s chemistry. Cells have
been grown on these materials and they have even been used to make
artificial pumps for neural transmitters. The switching voltages applied
to train the artificial synapse (about 0.5 mV) are also the same as
those that move through human neurons — about 1,000 times lower than the
“write” voltage for a typical memristor.
That means it’s possible that the artificial synapse could
communicate with live neurons, leading to improved brain-machine
interfaces. The softness and flexibility of the device also lends itself
to being used in biological environments.
This research was funded by the National Science Foundation, the Keck
Faculty Scholar Funds, the Neurofab at Stanford, the Stanford Graduate
Fellowship, Sandia’s Laboratory-Directed Research and Development
Program, the U.S. Department of Energy, the Holland Scholarship, the
University of Groningen Scholarship for Excellent Students, the Hendrik
Muller National Fund, the Schuurman Schimmel-van Outeren Foundation, the
Foundation of Renswoude (The Hague and Delft), the Marco Polo Fund, the
Instituto Nacional de Ciência e Tecnologia/Instituto Nacional de
Eletrônica Orgânica in Brazil, the Fundação de Amparo à Pesquisa do
Estado de São Paulo and the Brazilian National Council.
* “A resistive memory device has not yet been demonstrated with
adequate electrical characteristics to fully realize the efficiency and
performance gains of a neural architecture. State-of-the-art memristors
suffer from excessive write noise, write non-linearities, and high write
voltages and currents. Reducing the noise and lowering the switching
voltage significantly below 0.3 V (~10 kT) in a two-terminal device
without compromising long-term data retention has proven difficult.” … Organic memristive devices have been recently proposed, but are limited
by “the slow kinetics of ion diffusion through a polymer to retain their
states or on charge storage in metal nanoparticles, which inherently
limits performance and stability.” — Yoeri van de Burgt et al., Nature Materials ** ENODe switches at low voltage and energy (< 10 pJ for 1000-square-micrometer devices), compared to an estimated ∼ 1–100 fJ per synaptic event for the human brain. Abstract of A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing
The brain is capable of massively parallel information processing
while consuming only ~1–100 fJ per synaptic event. Inspired by the
efficiency of the brain, CMOS-based neural architectures and memristors
are being developed for pattern recognition and machine learning.
However, the volatility, design complexity and high supply voltages for
CMOS architectures, and the stochastic and energy-costly switching of
memristors complicate the path to achieve the interconnectivity,
information density, and energy efficiency of the brain using either
approach. Here we describe an electrochemical neuromorphic organic
device (ENODe) operating with a fundamentally different mechanism from
existing memristors. ENODe switches at low voltage and energy (<10 10="" for="" pj="" sup="">3
μm2 devices), displays >500 distinct,
non-volatile conductance states within a ~1 V range, and achieves high
classification accuracy when implemented in neural network simulations.
Plastic ENODes are also fabricated on flexible substrates enabling the
integration of neuromorphic functionality in stretchable electronic
systems. Mechanical flexibility makes ENODes compatible with
three-dimensional architectures, opening a path towards extreme
interconnectivity comparable to the human brain.
Nevertheless, the word índios ("Indians") was by then established to designate the people of the New World and continues to be used today in the Portuguese language to designate these people, while a person from India is called indiano in order to distinguish the two.
At the time of European contact, some of the indigenous people were traditionally mostly semi-nomadic tribes who subsisted on hunting, fishing, gathering, and migrant agriculture.
Many of the estimated 2,000 nations and tribes which existed in the
16th century suffered extinction as a consequence of the European
settlement, and many were assimilated into the Brazilian population.
The indigenous population was largely killed by European
diseases, declining from a pre-Columbian high of millions to some
300,000 (1997), grouped into 200 tribes. However, the number could be
much higher if the urban indigenous populations are counted in all the
Brazilian cities today. A somewhat dated linguistic survey[3] found 188 living indigenous languages with 155,000 total speakers.
On January 18, 2007, FUNAI reported that it had confirmed the presence of 67 different uncontacted tribes in Brazil, up from 40 in 2005. With this addition, Brazil has now surpassed New Guinea as the country having the largest number of uncontacted peoples in the world.[4]
In the last IBGE census (2010), 817,000 Brazilians classified themselves as indigenous.
Questions about the original settlement of the Americas has produced a number of hypothetical models. The origins of these indigenous people are still a matter of dispute among archaeologists.[5]
Migration into the continents
Anthropological and genetic evidence indicates that most Amerindian people descended from migrant people from North Asia (Siberia) who entered the Americas across the Bering Strait
or along the western coast of North America in at least three separate
waves. In Brazil, particularly, most native tribes who were living in
the land by 1500 are thought to be descended from the first Siberian
wave of migrants, who are believed to have crossed the Bering Land Bridge
at the end of the last Ice Age, between 13,000 and 17,000 years before
the present. A migrant wave would have taken some time after initial
entry to reach present-day Brazil, probably entering the Amazon River basin from the Northwest. (The second and third migratory waves from Siberia, which are thought to have generated the Athabaskan, Aleut, Inuit, and Yupik people, apparently did not reach farther than the southern United States and Canada, respectively).[6]
An analysis of Amerindian Y-chromosome DNA indicates specific clustering of much of the South American population. The micro-satellite
diversity and distributions of the Y lineage specific to South America
indicates that certain Amerindian populations have been isolated since
the initial colonization of the region.[7]
According to an autosomal genetic study from 2012,[8]
Native Americans descend from at least three main migrant waves from
East Asia. Most of it is traced back to a single ancestral population,
called 'First Americans'. However, those who speak Inuit languages from the Arctic inherited almost half of their ancestry from a second East Asian migrant wave. And those who speak Na-dene,
on the other hand, inherited a tenth of their ancestry from a third
migrant wave. The initial settling of the Americas was followed by a
rapid expansion southwards, by the coast, with little gene flow later,
especially in South America. One exception to this are the Chibcha speakers, whose ancestry comes from both North and South America.
[8]
Another study, focused on the mtDNA (that which is inherited only through the maternal line),[9]
revealed that the indigenous people of the Americas have their maternal
ancestry traced back to a few founding lineages from East Asia, which
would have arrived via the Bering strait.
According to this study, it is probable that the ancestors of the
Native Americans would have remained for a time in the region of the Bering Strait, after which there would have been a rapid movement of settling of the Americas, taking the founding lineages to South America.
Linguistic studies have backed up genetic studies, with ancient patterns having been found between the languages spoken in Siberia and those spoken in the Americas.[10]
Two 2015 autosomal DNA genetic studies confirmed the Siberian
origins of the Natives of the Americas. However an ancient signal of
shared ancestry with the Natives of Australia and Melanesia was detected
among the Natives of the Amazon region. The migration coming out of Siberia would have happened 23,000 years ago.[11][12][13]
According to a 2016 study, focused on mtDNA lineages, "a small
population entered the Americas via a coastal route around 16.0 ka,
following previous isolation in eastern Beringia for ~2.4 to 9 thousand
years after separation from eastern Siberian populations. Following a
rapid movement throughout the Americas, limited gene flow in South
America resulted in a marked phylogeographic structure of populations,
which persisted through time. All of the ancient mitochondrial lineages
detected in this study were absent from modern data sets, suggesting a
high extinction rate. To investigate this further, we applied a novel
principal components multiple logistic regression
test to Bayesian serial coalescent simulations. The analysis supported a
scenario in which European colonization caused a substantial loss of
pre-Columbian lineages".[14]
Archaeological remains
Terena people
Brazilian native people, unlike those in Mesoamerica and the western Andes,
did not keep written records or erect stone monuments, and the humid
climate and acidic soil have destroyed almost all traces of their
material culture, including wood and bones.
Therefore, what is known about the region's history before 1500 has
been inferred and reconstructed from small-scale archaeological
evidence, such as ceramics and stone arrowheads.
The most conspicuous remains of these societies are very large mounds of discarded shellfish (sambaquis) found in some coastal sites which were continuously inhabited for over 5,000 years; and the substantial "black earth" (terra preta) deposits in several places along the Amazon, which are believed to be ancient garbage dumps (middens).
Recent excavations of such deposits in the middle and upper course of
the Amazon have uncovered remains of some very large settlements,
containing tens of thousands of homes, indicating a complex social and
economic structure.[15]
Marajoara culture
Marajoara culture flourished on Marajó island at the mouth of the Amazon River.[16] Archeologists have found sophisticated pottery
in their excavations on the island. These pieces are large, and
elaborately painted and incised with representations of plants and
animals. These provided the first evidence that a complex society had
existed on Marajó. Evidence of mound building
further suggests that well-populated, complex and sophisticated
settlements developed on this island, as only such settlements were
believed capable of such extended projects as major earthworks.[17]
The extent, level of complexity, and resource interactions of the
Marajoara culture have been disputed. Working in the 1950s in some of
her earliest research, American Betty Meggers
suggested that the society migrated from the Andes and settled on the
island. Many researchers believed that the Andes were populated by
Paleoindian migrants from North America who gradually moved south after
being hunters on the plains.
In the 1980s, another American archeologist, Anna Curtenius Roosevelt,
led excavations and geophysical surveys of the mound Teso dos Bichos.
She concluded that the society that constructed the mounds originated on
the island itself.[18]
The pre-Columbian culture of Marajó may have developed social stratification and supported a population as large as 100,000 people.[16] The Native Americans of the Amazon rain forest may have used their method of developing and working in Terra preta
to make the land suitable for the large-scale agriculture needed to
support large populations and complex social formations such as chiefdoms.[16]
Native people after the European colonization
Distribution
Distribution of Tupi and Tapuia people on the coast of Brazil, on the eve of colonialism in the 16th century
On the eve of the Portuguese arrival in 1500, the coastal areas of Brazil had two major mega-groups - the Tupi (speakers of Tupi–Guarani languages), who dominated practically the entire length of the Brazilian coast, and the Tapuia (a catch-all term for non-Tupis, usually Jê language
people), who resided primarily in the interior. The Portuguese arrived
in the final days of a long pre-colonial struggle between Tupis and
Tapuias, which had resulted in the defeat and expulsion of the Tapuias
from most coastal areas.
Although the coastal Tupi were broken down into sub-tribes,
frequently hostile to each other, they were culturally and
linguistically homogeneous. The fact that the early Europeans
encountered practically the same people and language all along the
Brazilian coast greatly simplified early communication and interaction.
Tremembé (Tapuia, coastal tribe, ranged from São Luis Island (south Maranhão) to the mouth of the Acaraú River in north Ceará; French traders cultivated an alliance with them)
Potiguara
(Tupi, literally "shrimp-eaters"; they had a reputation as great
canoeists and aggressively expansionist, inhabited a great coastal
stretch from Acaraú River to Itamaracá island, covering the modern states of southern Ceará, Rio Grande do Norte and Paraíba.)
Tabajara (tiny Tupi tribe between Itamaracá island and Paraiba River; neighbors and frequent victims of the Potiguara)
Caeté (Tupi group in Pernambuco, ranged from Paraiba River to the São Francisco River;
after killing and eating a Portuguese bishop, they were subjected to
Portuguese extermination raids and the remnant pushed into the Pará
interior)
Tupinambá again (Tupi par excellence, ranged from the São Francisco River to the Bay of All Saints, population estimated as high as 100,000; hosted Portuguese castaway Caramuru)
Aimoré (Tapuia (Jê) tribe; concentrated on a sliver of coast in modern Espírito Santo state)
Goitacá (Tapuia tribe; once dominated the coast from São Mateus River (in Espírito Santo state) down to the Paraíba do Sul river (in Rio de Janeiro
state); hunter-gatherers and fishermen, they were a shy people that
avoided all contact with foreigners; estimated at 12,000; they had a
fearsome reputation and were eventually annihilated by European
colonists)
Tamoio (Tupi, old branch of the Tupinambá, ranged from the western edge of Guanabara bay to Ilha Grande)
Tupinambá again (Tupi, indistinct from the Tamoio. Inhabited the Paulist coast, from Ilha Grande to Santos; main enemies of the Tupiniquim to their west. Numbered between six and ten thousand).
Tupiniquim again (Tupi, on the São Paulo coast from Santos/Bertioga down to Cananéia; aggressively expansionist, they were recent arrivals imposing themselves on the Paulist coast and the Piratininga plateau at the expense of older Tupinambá and Carijó neighbors; hosted Portuguese castaways João Ramalho
('Tamarutaca') and António Rodrigues in the early 1500s; the Tupiniquim
were the first formal allies of the Portuguese colonists, helped
establish the Portuguese Captaincy of São Vicente in the 1530s; sometimes called "Guaianá" in old Portuguese chronicles, a Tupi term meaning "friendly" or "allied")
Charrúa (Tapuia (Jê) tribe in modern Uruguay coast, with an aggressive reputation against intruders; killed Juan Díaz de Solís in 1516)
With the exception of the hunter-gathererGoitacases, the coastal Tupi and Tapuia tribes were primarily agriculturalists. The subtropical Guarani cultivated maize, tropical Tupi cultivated manioc (cassava), highland Jês cultivated peanut, as the staple of their diet. Supplementary crops included beans, sweet potatoes, cará (yam), jerimum (pumpkin), and cumari (capsicum pepper).
Behind these coasts, the interior of Brazil was dominated
primarily by Tapuia (Jê) people, although significant sections of the
interior (notably the upper reaches of the Xingu, Teles Pires and Juruena Rivers - the area now covered roughly by modern Mato Grosso
state) were the original pre-migration Tupi-Guarani homelands. Besides
the Tupi and Tapuia, it is common to identify two other indigenous
mega-groups in the interior: the Caribs, who inhabited much of what is now northwestern Brazil, including both shores of the Amazon River up to the delta and the Nuaraque group, whose constituent tribes inhabited several areas, including most of the upper Amazon (west of what is now Manaus) and also significant pockets in modern Amapá and Roraima states.
The names by which the different Tupi tribes were recorded by
Portuguese and French authors of the 16th century are poorly understood.
Most do not seem to be proper names, but descriptions of relationship,
usually familial - e.g. tupi means "first father", tupinambá means "relatives of the ancestors", tupiniquim means "side-neighbors", tamoio means "grandfather", temiminó means "grandson", tabajara means "in-laws" and so on.[20]
Some etymologists believe these names reflect the ordering of the
migration waves of Tupi people from the interior to the coasts, e.g.
first Tupi wave to reach the coast being the "grandfathers" (Tamoio),
soon joined by the "relatives of the ancients" (Tupinamba), by which it
could mean relatives of the Tamoio, or a Tamoio term to refer to
relatives of the old Tupi back in the upper Amazon basin. The
"grandsons" (Temiminó) might be a splinter. The "side-neighbors"
(Tupiniquim) meant perhaps recent arrivals, still trying to jostle their
way in. However, by 1870 the Tupi tribes population had declined to
250,000 indígenas and by 1890 had diminished to an approximate 100,000
tribes.
Native Brazilian Population in Northeast Coast (Dutch estimatives).[21]
When the Portuguese
explorers first arrived in Brazil in April 1500, they found, to their
astonishment, a wide coastline rich in resources, teeming with hundreds
of thousands of Indigenous people living in a "paradise" of natural
riches. Pêro Vaz de Caminha, the official scribe of Pedro Álvares Cabral, the commander of the discovery fleet which landed in the present state of Bahia, wrote a letter to the King of Portugal describing in glowing terms the beauty of the land.
At the time of European arrival, the territory of current day
Brazil had as many as 2,000 nations and tribes. The indigenous people
were traditionally mostly semi-nomadic tribes who subsisted on hunting,
fishing, gathering, and migrant agriculture. For hundreds of years, the
indigenous people of Brazil lived a semi-nomadic life, managing the
forests to meet their needs. When the Portuguese arrived in 1500, the
natives were living mainly on the coast and along the banks of major
rivers. Initially, the Europeans saw native people as noble savages, and
miscegenation of the population began right away. Portuguese claims of tribal warfare, cannibalism, and the pursuit of Amazonian brazilwood
for its treasured red dye convinced the Portuguese that they should
"civilize" the natives (originally, colonists called Brazil Terra de Santa Cruz, until later it acquired its name (see List of meanings of countries' names) from brazilwood).
But the Portuguese, like the Spanish in their North American
territories, had brought diseases with them against which many Indians
were helpless due to lack of immunity. Measles, smallpox, tuberculosis, and influenza
killed tens of thousands. The diseases spread quickly along the
indigenous trade routes, and it is likely that whole tribes were
annihilated without ever coming in direct contact with Europeans.
The mutual feeling of wonderment and good relationship was to end in the succeeding years.
The Portuguese colonists,
all males, started to have children with female Amerindians, creating a
new generation of mixed-race people who spoke Indian languages (a Tupi language called Nheengatu).
The children of these Portuguese men and Indian women formed the
majority of the population. Groups of fierce pathfinders organized
expeditions called "bandeiras" (flags) into the backlands to claim them for the Portuguese crown and to look for gold and precious stones.
Intending to profit from sugar trade, the Portuguese decided to plant sugar cane
in Brazil, and to use indigenous slaves as the workforce, as the
Spanish colonies were successfully doing. But the indigenous people were
hard to capture. They were soon infected by diseases brought by the
Europeans against which they had no natural immunity, and began dying in great numbers.
The Jesuit priests, who had come with the first Governor General to provide religious assistance to the colonists, but mainly to convert the Pagan people to Catholicism, took the side of the Indians and extracted a Papal bull stating that they were human and should be protected.
Jesuit priests such as fathers José de Anchieta and Manuel da Nóbrega studied and recorded their language and founded mixed settlements, such as São Paulo dos Campos de Piratininga, where colonists and Indians lived side by side, speaking the same Língua Geral
(common language) and freely intermarried. They began also to establish
more remote villages peopled only by "civilized" Indians, called Missions, or reductions (see the article on the Guarani people for more details).
By the middle of the 16th century, Catholic Jesuit
priests, at the behest of Portugal's monarchy, had established missions
throughout the country's colonies. They became protectors of the
Indians and worked to both Europeanize them and convert them to Catholicism. The Jesuits provided a period of relative stability for the Indians.
In the mid-1770s, the Indians' fragile co-existence with the
colonists was again threatened. Because of a complex diplomatic web
between Portugal, Spain and the Vatican, the Jesuits were expelled from Brazil and the missions confiscated and sold.
By 1800, the population of Brazil had reached approximately 3.25 million, of which only 250,000 were indigenous. And for the next four decades, the Indians were largely left alone.
A number of wars between several tribes, such as the Tamoio Confederation,
and the Portuguese ensued, sometimes with the Indians siding with
enemies of Portugal, such as the French, in the famous episode of France Antarctique in Rio de Janeiro,
sometimes allying themselves to Portugal in their fight against other
tribes. At approximately the same period, a German soldier, Hans Staden, was captured by the Tupinambá and released after a while. He described it in a famous book, Warhaftige
Historia und beschreibung eyner Landtschafft der Wilden Nacketen,
Grimmigen Menschfresser-Leuthen in der Newenwelt America gelegen (True Story and Description of a Country of Wild, Naked, Grim, Man-eating People in the New World, America) (1557)
There are various documented accounts of smallpox
being knowingly used as a biological weapon by New Brazilian villagers
that wanted to get rid of nearby Indian tribes (not always aggressive
ones). The most "classical", according to Anthropologist, Mércio Pereira
Gomes, happened in Caxias, in south Maranhão, where local farmers,
wanting more land to extend their cattle farms, gave clothing owned by
ill villagers (that normally would be burned to prevent further
infection) to the Timbira. The clothing infected the entire tribe, and
they had neither immunity nor cure. Similar things happened in other
villages throughout South America.[22]
The rubber trade
The 1840s brought trade and wealth to the Amazon. The process for vulcanizingrubber was developed, and worldwide demand for the product skyrocketed. The best rubber trees
in the world grew in the Amazon, and thousands of rubber tappers began
to work the plantations. When the Indians proved to be a difficult labor
force, peasants from surrounding areas were brought into the region. In
a dynamic that continues to this day, the indigenous population was at
constant odds with the peasants, who the Indians felt had invaded their
lands in search of treasure.
In the 20th century, the Brazilian Government adopted a more
humanitarian attitude and offered official protection to the indigenous
people, including the establishment of the first indigenous reserves.
Fortune brightened for the Indians around the turn of the 20th century
when Cândido Rondon, a man of both Portuguese and Bororo
ancestry, and an explorer and progressive officer in the Brazilian
army, began working to gain the Indians' trust and establish peace.
Rondon, who had been assigned to help bring telegraph communications
into the Amazon, was a curious and natural explorer. In 1910, he helped
found the Serviço de Proteção aos Índios - SPI (Service for the Protection of Indians, today the FUNAI, or Fundação Nacional do Índio,
National Foundation for Indians). SPI was the first federal agency
charged with protecting Indians and preserving their culture. In 1914,
Rondon accompanied Theodore Roosevelt
on Roosevelt's famous expedition to map the Amazon and discover new
species. During these travels, Rondon was appalled to see how settlers
and developers treated the indigenes, and he became their lifelong
friend and protector.
Rondon, who died in 1958, is a national hero in Brazil. The Brazilian state of Rondônia is named after him.
After Rondon's pioneering work, the SPI was turned over to
bureaucrats and military officers and its work declined after 1957. The
new officials did not share Rondon's deep commitment to the Indians. SPI
sought to address tribal issues by transforming the tribes into
mainstream Brazilian society. The lure of reservation riches enticed
cattle ranchers and settlers to continue their assault on Indians lands –
and the SPI eased the way. Between 1900 and 1967, an estimated 98 indigenous tribes were wiped out.[citation needed]
Mostly due to the efforts of the Villas-Bôas brothers, Brazil's first Indian reserve, the Xingu National Park, was established by the Federal Government in 1961.
During the social and political upheaval in the 1960s, reports of mistreatment of Indians increasingly reached Brazil's urban centers and began to affect Brazilian thinking. In 1967, following the publication of the Figueiredo Report,
commissioned by the Ministry of the Interior, the military government
launched an investigation into SPI. It soon came to light that the SPI
was corrupt and failing to protect natives, their lands, and, culture.
The 5,000-page report catalogued atrocities including slavery, sexual
abuse, torture, and mass murder.[23]
It has been charged that agency officials, in collaboration with land
speculators, were systematically slaughtering the Indians by
intentionally circulating disease-laced clothes.[citation needed] Criminal prosecutions followed, and the SPI was disbanded. The same year the government established Fundação Nacional do Índio (National Indian Foundation),
known as FUNAI which is responsible for protecting the interests,
cultures, and rights of the Brazilian indigenous populations.
Some tribes have become significantly integrated into Brazilian society.
The unacculturated tribes which have been contacted by FUNAI, are
supposed to be protected and accommodated within Brazilian society in
varying degrees. By 1987 it was recognized that unessential contact with
the tribes was causing illness and social disintegration. The
uncontacted tribes are now supposed to be protected from intrusion and
interference in their life style and territory.[23]
However, the exploitation of rubber
and other Amazonic natural resources has led to a new cycle of
invasion, expulsion, massacres and death, which continues to this day.[citation needed]
The military government
Also in 1964, in a seismic political shift, the Brazilian military took control of the government
and abolished all existing political parties, creating a two-party
system. For the next two decades, Brazil was ruled by a series of
generals. The country's mantra was "Brazil, the Country of the Future,"
which the military government used as justification for a giant push
into the Amazon to exploit its resources, thereby beginning to transform
Brazil into one of the leading economies of the world. Construction
began on a transcontinental highway across the Amazon basin, aimed to encourage migration to the Amazon
and to open up the region to more trade. With funding from World Bank,
thousands of square miles of forest were cleared without regard for
reservation status. After the highway projects came giant hydroelectric
projects, then swaths of forest were cleared for cattle ranches. As a
result, reservation lands suffered massive deforestation and flooding.
The public works projects attracted very few migrants, but those few –
and largely poor - settlers brought new diseases that further devastated
the Indians population.
The 1988 Brazilian Constitution
recognises indigenous people' right to pursue their traditional ways of
life and to the permanent and exclusive possession of their
"traditional lands", which are demarcated as Indigenous Territories.[24]
In practice, however, Brazil's indigenous people still face a number of
external threats and challenges to their continued existence and
cultural heritage.[25] The process of demarcation is slow—often involving protracted legal battles—and FUNAI do not have sufficient resources to enforce the legal protection on indigenous land.[26][25][27][28][29]
Since the 1980s there has been a boom in the exploitation of the Amazon
Rainforest for mining, logging and cattle ranching, posing a severe
threat to the region's indigenous population. Settlers illegally
encroaching on indigenous land continue to destroy the environment
necessary for indigenous people' traditional ways of life, provoke
violent confrontations and spread disease.[25] people such as the Akuntsu and Kanoê have been brought to the brink of extinction within the last three decades.[30][31] On 13 November 2012, the national indigenous people association from
Brazil APIB submitted to the United Nation a human rights document that
complaints about new proposed laws in Brazil that would further
undermine their rights if approved.[4]
Much of the language has been incorporated into the official
Brazilian Portuguese language. For example, 'Carioca' the word used to
describe people born in the city of Rio de Janeiro, is from the
indigenous word for 'house of the white (people)'[32].
Indigenous Rights Movements
Urban Rights Movement
The
urban rights movement is a recent development in the rights of
indigenous peoples. Brazil has one of the highest income inequalities in
the world,[33]
and much of that population includes indigenous tribes migrating toward
urban areas both by choice and by displacement. Beyond the urban rights
movement, studies have shown that the suicide risk among the indigenous
population is 8.1 times higher than the non-indigenous population.[34]
Many indigenous rights movements have been created through the
meeting of many indigenous tribes in urban areas. For example, in
Barcelos, an indigenous rights movement arose because of "local
migratory circulation.[35]"
This is how many alliances form to create a stronger network for
mobilization. Indigenous populations also living in urban areas have
struggles regarding work. They are pressured into doing cheap labor.[36] Programs like Oxfam have been used to help indigenous people gain partnerships to begin grassroots movements.[37] Some of their projects overlap with environmental activism as well.
Many Brazilian youths are mobilizing through the increased social
contact, since some indigenous tribes stay isolated while others adapt
to the change.[38] Access to education also affects these youths, and therefore, more groups are mobilizing to fight for indigenous rights.
Environmental and Territorial Rights Movement
Much
of Indigenous tribes' rights parallel the environmental and territorial
rights movement. Although indigenous people have gained 21% of the
Brazilian Amazon as part of indigenous land, there are many issues still
today that affect the sustainability of Indigenous territories today.[39] Environmentalists and indigenous peoples have been viewed as opponents to economic growth and barriers to development[40]
due to the fact that much of the land that indigenous tribes live on
could be used for development projects and more industrialization.
Currently, 15% of global greenhouse gas emissions can be attributed to
forest clearing and degradation. Deforestation for mining also affects
the daily lives of indigenous tribes in Brazil.[41] The Munduruku Indians have higher levels of mercury poisoning due to gold production in the area.[42] Climate change is one issue that indigenous tribes attribute as a reason to keep their territory.
There are a lot of alliances between indigenous peoples and
conservation organizations in the Brazilian Amazon.The A'ukre Kayapo
village and the Instituto SocioAmbiental (ISA) environmental
organization is a good example of one of these alliances. They focus on
environmental, education and developmental rights.[43]
For example, Amazon Watch collaborates with various indigenous
organizations in Brazil to fight for both territorial and environmental
rights.[44] "Access to natural resources by indigenous and peasant communities in Brazil has been considerably less and much more insecure,[45]" so activists focus on more traditional conservation efforts, and expanding territorial rights for indigenous people.
Territorial rights for the indigenous populations of Brazil
largely fall under socio-economic issues. There have been violent
conflicts regarding rights to land between the government and the
indigenous population,[41]
and political rights have done little to stop them. There have been
movements of the landless (MST) that helps keep land away from the elite
living in Brazil.
From
left to right: an example of an original galaxy image; the same image
deliberately degraded; the image after recovery by the neural network;
and for comparison, deconvolution. This figure visually illustrates the
neural-networks’s ability to recover features that conventional
deconvolutions cannot. (credit: K. Schawinski / C. Zhang / ETH Zurich)
Swiss researchers are using neural networks to achieve the sharpest-ever images in optical astronomy. The work appears in an open-access paper in Monthly Notices of the Royal Astronomical Society.
The aperture
(diameter) of any telescope is fundamentally limited by its lens or
mirror. The bigger the mirror or lens, the more light it gathers,
allowing astronomers to detect fainter objects, and to observe them more
clearly. Other factors affecting image quality are noise and
atmospheric distortion.
The Swiss study uses “generative adversarial network” (GAN) machine-learning technology (see this KurzweilAI article)
to go beyond this limit by using two neural networks that compete with
each other to create a series of more realistic images. The researchers
first train the neural network to “see” what galaxies look like (using
blurred and sharp images of the same galaxy), and then ask it to
automatically fix the blurred images of a galaxy, converting them to
sharp ones.
Schematic
illustration of the neural-network training process. The input is a set
of original images. From these, the researchers automatically generate
degraded images, and train a GAN. In the testing phase, only the
generator will be used to recover images. (credit: K. Schawinski / C.
Zhang / ETH Zurich)
The trained neural networks were able to recognize and reconstruct
features that the telescope could not resolve, such as star-forming
regions and dust lanes in galaxies. The scientists checked the
reconstructed images against the original high-resolution images to test
its performance, finding it better able to recover features than
anything used to date.
“We can start by going back to sky surveys made with telescopes over
many years, see more detail than ever before, and, for example, learn
more about the structure of galaxies,” said lead author Prof. Kevin Schawinski of ETH Zurich
in Switzerland. “There is no reason why we can’t then apply this
technique to the deepest images from Hubble, and the coming James Webb
Space Telescope, to learn more about the earliest structures in the
Universe.”
ETH Zurich is hosting this work on the space.ml cross-disciplinary astrophysics/computer-science initiative, where the code is available to the general public.
Abstract of Generative adversarial networks recover features in astrophysical images of galaxies beyond the deconvolution limit
Observations of astrophysical objects such as galaxies are limited by
various sources of random and systematic noise from the sky background,
the optical system of the telescope and the detector used to record the
data. Conventional deconvolution techniques are limited in their
ability to recover features in imaging data by the Shannon–Nyquist
sampling theorem. Here, we train a generative adversarial network (GAN)
on a sample of 4550 images of nearby galaxies at 0.01 < z < 0.02
from the Sloan Digital Sky Survey and conduct 10× cross-validation to
evaluate the results. We present a method using a GAN trained on galaxy
images that can recover features from artificially degraded images with
worse seeing and higher noise than the original with a performance that
far exceeds simple deconvolution. The ability to better recover detailed
features such as galaxy morphology from low signal to noise and low
angular resolution imaging data significantly increases our ability to
study existing data sets of astrophysical objects as well as future
observations with observatories such as the Large Synoptic Sky Telescope
(LSST) and the Hubble and James Webb space telescopes.
Map of the Amazon rainforest ecoregions as delineated by the WWF. The yellow line approximately encloses the Amazon drainage basin. National boundaries are shown in black. (Satellite image from NASA)
The Amazon rainforest (Portuguese: Floresta Amazônica or Amazônia; Spanish: Selva Amazónica, Amazonía or usually Amazonia; French: Forêt amazonienne; Dutch: Amazoneregenwoud), also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest in the Amazon biome that covers most of the Amazon basin of South America. This basin encompasses 7,000,000 km2 (2,700,000 sq mi), of which 5,500,000 km2
(2,100,000 sq mi) are covered by the rainforest. This region includes
territory belonging to nine nations. The majority of the forest is
contained within Brazil, with 60% of the rainforest, followed by Peru with 13%, Colombia with 10%, and with minor amounts in Venezuela, Ecuador, Bolivia, Guyana, Suriname and French Guiana. States or departments in four nations contain "Amazonas" in their names. The Amazon represents over half of the planet's remaining rainforests, and comprises the largest and most biodiverse tract of tropical rainforest in the world, with an estimated 390 billion individual trees divided into 16,000 species.
Etymology
The name Amazon is said to arise from a war Francisco de Orellana fought with the Tapuyas and other tribes. The women of the tribe fought alongside the men, as was their custom.[3] Orellana derived the name Amazonas from the Amazons of Greek mythology, described by Herodotus and Diodorus.[3]
The rainforest likely formed during the Eocene
era. It appeared following a global reduction of tropical temperatures
when the Atlantic Ocean had widened sufficiently to provide a warm,
moist climate to the Amazon basin. The rainforest has been in existence
for at least 55 million years, and most of the region remained free of savanna-type biomes at least until the current ice age, when the climate was drier and savanna more widespread.[4][5]
Following the Cretaceous–Paleogene extinction event, the extinction of the dinosaurs and the wetter climate may have allowed the tropical rainforest to spread out across the continent. From 66–34 Mya, the rainforest extended as far south as 45°. Climate fluctuations during the last 34 million years have allowed savanna regions to expand into the tropics. During the Oligocene, for example, the rainforest spanned a relatively narrow band. It expanded again during the Middle Miocene, then retracted to a mostly inland formation at the last glacial maximum.[6]
However, the rainforest still managed to thrive during these glacial
periods, allowing for the survival and evolution of a broad diversity of
species.[7]
Aerial view of the Amazon rainforest.
During the mid-Eocene, it is believed that the drainage basin of the Amazon was split along the middle of the continent by the Purus Arch. Water on the eastern side flowed toward the Atlantic, while to the west water flowed toward the Pacific across the Amazonas Basin. As the Andes Mountains rose, however, a large basin was created that enclosed a lake; now known as the Solimões Basin.
Within the last 5–10 million years, this accumulating water broke
through the Purus Arch, joining the easterly flow toward the Atlantic.[8][9]
There is evidence that there have been significant changes in Amazon rainforest vegetation over the last 21,000 years through the Last Glacial Maximum
(LGM) and subsequent deglaciation. Analyses of sediment deposits from
Amazon basin paleolakes and from the Amazon Fan indicate that rainfall
in the basin during the LGM was lower than for the present, and this was
almost certainly associated with reduced moist tropical vegetation
cover in the basin.[10]
There is debate, however, over how extensive this reduction was. Some
scientists argue that the rainforest was reduced to small, isolated refugia separated by open forest and grassland;[11]
other scientists argue that the rainforest remained largely intact but
extended less far to the north, south, and east than is seen today.[12]
This debate has proved difficult to resolve because the practical
limitations of working in the rainforest mean that data sampling is
biased away from the center of the Amazon basin, and both explanations
are reasonably well supported by the available data.
Sahara Desert dust windblown to the Amazon
More than 56% of the dust fertilizing the Amazon rainforest comes from the Bodélé depression in Northern Chad in the Sahara desert. The dust contains phosphorus,
important for plant growth. The yearly Sahara dust replaces the
equivalent amount of phosphorus washed away yearly in Amazon soil from
rains and floods.[13] Up to 50 million tonnes of Sahara dust per year are blown across the Atlantic Ocean.
NASA's CALIPSO
satellite has measured the amount of dust transported by wind from the
Sahara to the Amazon: an average 182 million tons of dust are windblown
out of the Sahara each year, at 15 degrees west longitude, across 1,600
miles (2,600 km) over the Atlantic Ocean (some dust falls into the
Atlantic), then at 35 degrees West longitude at the eastern coast of
South America, 27.7 million tons (15%) of dust fall over the Amazon
basin, 132 million tons of dust remain in the air, 43 million tons of
dust are windblown and falls on the Caribbean Sea, past 75 degrees west
longitude.[16]
CALIPSO uses a laser range finder to scan the Earth's atmosphere
for the vertical distribution of dust and other aerosols. CALIPSO
regularly tracks the Sahara-Amazon dust plume. CALIPSO has measured
variations in the dust amounts transported— an 86 percent drop between
the highest amount of dust transported in 2007 and the lowest in 2011.
A possibility causing the variation is the Sahel,
a strip of semi-arid land on the southern border of the Sahara. When
rain amounts in the Sahel are higher, the volume of dust is lower. The
higher rainfall could make more vegetation grow in the Sahel, leaving
less sand exposed to winds to blow away.[17]
Based on archaeological evidence from an excavation at Caverna da Pedra Pintada, human inhabitants first settled in the Amazon region at least 11,200 years ago.[18]
Subsequent development led to late-prehistoric settlements along the
periphery of the forest by AD 1250, which induced alterations in the
forest cover.[19]
Geoglyphs on deforested land in the Amazon rainforest, Acre.
For a long time, it was thought that the Amazon rainforest was only
ever sparsely populated, as it was impossible to sustain a large
population through agriculture given the poor soil. Archeologist Betty Meggers was a prominent proponent of this idea, as described in her book Amazonia: Man and Culture in a Counterfeit Paradise.
She claimed that a population density of 0.2 inhabitants per square
kilometre (0.52/sq mi) is the maximum that can be sustained in the
rainforest through hunting, with agriculture needed to host a larger
population.[20] However, recent anthropological
findings have suggested that the region was actually densely populated.
Some 5 million people may have lived in the Amazon region in AD 1500,
divided between dense coastal settlements, such as that at Marajó, and inland dwellers.[21] By 1900 the population had fallen to 1 million and by the early 1980s it was less than 200,000.[21]
The first European to travel the length of the Amazon River was Francisco de Orellana in 1542.[22] The BBC's Unnatural Histories
presents evidence that Orellana, rather than exaggerating his claims as
previously thought, was correct in his observations that a complex
civilization was flourishing along the Amazon in the 1540s. It is
believed that the civilization was later devastated by the spread of
diseases from Europe, such as smallpox.[23]
Since the 1970s, numerous geoglyphs have been discovered on deforested land dating between AD 1–1250, furthering claims about Pre-Columbian civilizations.[24][25]
Ondemar Dias is accredited with first discovering the geoglyphs in 1977
and Alceu Ranzi with furthering their discovery after flying over Acre.[23][26] The BBC's Unnatural Histories presented evidence that the Amazon rainforest, rather than being a pristine wilderness, has been shaped by man for at least 11,000 years through practices such as forest gardening and terra preta.[23]
Terra preta is found over large areas in the Amazon forest; and is now
widely accepted as a product of indigenous soil management. The
development of this fertile soil allowed agriculture and silviculture
in the previously hostile environment; meaning that large portions of
the Amazon rainforest are probably the result of centuries of human
management, rather than naturally occurring as has previously been
supposed.[27] In the region of the Xingu
tribe, remains of some of these large settlements in the middle of the
Amazon forest were found in 2003 by Michael Heckenberger and colleagues
of the University of Florida. Among those were evidence of roads, bridges and large plazas.[28]
Biodiversity
Deforestation
in the Amazon rainforest threatens many species of tree frogs, which
are very sensitive to environmental changes (pictured: giant leaf frog)
Scarlet macaw, which is indigenous to the American tropics.
Wet tropical forests are the most species-rich biome, and tropical forests in the Americas are consistently more species rich than the wet forests in Africa and Asia.[29] As the largest tract of tropical rainforest in the Americas, the Amazonian rainforests have unparalleled biodiversity. One in ten known species in the world lives in the Amazon rainforest.[30] This constitutes the largest collection of living plants and animalspecies in the world.
The region is home to about 2.5 million insectspecies,[31] tens of thousands of plants, and some 2,000 birds and mammals. To date, at least 40,000 plant species, 2,200 fishes,[32] 1,294 birds, 427 mammals, 428 amphibians, and 378 reptiles have been scientifically classified in the region.[33]
One in five of all bird species are found in the Amazon rainforest, and
one in five of the fish species live in Amazonian rivers and streams.
Scientists have described between 96,660 and 128,843 invertebrate species in Brazil alone.[34]
The biodiversity of plant species is the highest on Earth with
one 2001 study finding a quarter square kilometer (62 acres) of
Ecuadorian rainforest supports more than 1,100 tree species.[35]
A study in 1999 found one square kilometer (247 acres) of Amazon
rainforest can contain about 90,790 tonnes of living plants. The average
plant biomass is estimated at 356 ± 47 tonnes per hectare.[36]
To date, an estimated 438,000 species of plants of economic and social
interest have been registered in the region with many more remaining to
be discovered or catalogued.[37] The total number of tree species in the region is estimated at 16,000.[2]
The green leaf area of plants and trees in the rainforest varies by
about 25% as a result of seasonal changes. Leaves expand during the dry
season when sunlight is at a maximum, then undergo abscission in the
cloudy wet season. These changes provide a balance of carbon between
photosynthesis and respiration.[38]
The rainforest contains several species that can pose a hazard. Among the largest predatory creatures are the black caiman, jaguar, cougar, and anaconda. In the river, electric eels can produce an electric shock that can stun or kill, while piranha are known to bite and injure humans.[39] Various species of poison dart frogs secrete lipophilicalkaloid toxins through their flesh. There are also numerous parasites and disease vectors. Vampire bats dwell in the rainforest and can spread the rabies virus.[40]Malaria, yellow fever and Dengue fever can also be contracted in the Amazon region.
Deforestation in the Maranhão state of Brazil, 2016
Deforestation
is the conversion of forested areas to non-forested areas. The main
sources of deforestation in the Amazon are human settlement and
development of the land.[41] Prior to the early 1960s, access to the forest's interior was highly restricted, and the forest remained basically intact.[42] Farms established during the 1960s were based on crop cultivation and the slash and burn method. However, the colonists were unable to manage their fields and the crops because of the loss of soil fertility and weed invasion.[43]
The soils in the Amazon are productive for just a short period of time,
so farmers are constantly moving to new areas and clearing more land.[43] These farming practices led to deforestation and caused extensive environmental damage.[44] Deforestation is considerable, and areas cleared of forest are visible to the naked eye from outer space.
In the 1970s construction began on the Trans-Amazonian highway. This highway represented a major threat to the Amazon rainforest.[45] Fortunately for the rainforest, the highway has not been completed, hereby reducing the environmental damage.
Between 1991 and 2000, the total area of forest lost in the
Amazon rose from 415,000 to 587,000 square kilometres (160,000 to
227,000 sq mi), with most of the lost forest becoming pasture for
cattle.[46] Seventy percent of formerly forested land in the Amazon, and 91% of land deforested since 1970, is used for livestock pasture.[47][48] Currently, Brazil is the second-largest global producer of soybeans
after the United States. New research however, conducted by Leydimere
Oliveira et al., has shown that the more rainforest is logged in the
Amazon, the less precipitation reaches the area and so the lower the
yield per hectare becomes. So despite the popular perception, there has
been no economical advantage for Brazil from logging rainforest zones
and converting these to pastoral fields.[49]
The needs of soy farmers have been used to justify many of the
controversial transportation projects that are currently developing in
the Amazon. The first two highways successfully opened up the rainforest
and led to increased settlement and deforestation. The mean annual
deforestation rate from 2000 to 2005 (22,392 km2 or 8,646 sq mi per year) was 18% higher than in the previous five years (19,018 km2 or 7,343 sq mi per year).[50]
Although deforestation has declined significantly in the Brazilian
Amazon between 2004 and 2014, there has been an increase to the present
day.[51]
NASA satellite observation of deforestation in the Mato Grosso state
of Brazil. The transformation from forest to farm is evident by the
paler square shaped areas under development.
One consequence of forest clearing in the Amazon: thick smoke that hangs over the forest.
Conservation and climate change
Amazon rainforest
Environmentalists are concerned about loss of biodiversity that will
result from destruction of the forest, and also about the release of the
carbon contained within the vegetation, which could accelerate global warming.
Amazonian evergreen forests account for about 10% of the world's
terrestrial primary productivity and 10% of the carbon stores in
ecosystems[52]—of the order of 1.1 × 1011 metric tonnes of carbon.[53] Amazonian forests are estimated to have accumulated 0.62 ± 0.37 tons of carbon per hectare per year between 1975 and 1996.[53]
One computer model of future climate change caused by greenhouse gas
emissions shows that the Amazon rainforest could become unsustainable
under conditions of severely reduced rainfall and increased
temperatures, leading to an almost complete loss of rainforest cover in
the basin by 2100.[54][55]
However, simulations of Amazon basin climate change across many
different models are not consistent in their estimation of any rainfall
response, ranging from weak increases to strong decreases.[56]
The result indicates that the rainforest could be threatened though the
21st century by climate change in addition to deforestation.
In 1989, environmentalist C.M. Peters and two colleagues stated
there is economic as well as biological incentive to protecting the
rainforest. One hectare in the Peruvian Amazon has been calculated to have a value of $6820 if intact forest
is sustainably harvested for fruits, latex, and timber; $1000 if
clear-cut for commercial timber (not sustainably harvested); or $148 if
used as cattle pasture.[57]
As indigenous territories continue to be destroyed by deforestation and ecocide, such as in the Peruvian Amazon[58]indigenous peoples' rainforest communities continue to disappear, while others, like the Urarina
continue to struggle to fight for their cultural survival and the fate
of their forested territories. Meanwhile, the relationship between
non-human primates in the subsistence and symbolism of indigenous
lowland South American peoples has gained increased attention, as have
ethno-biology and community-based conservation efforts.
From 2002 to 2006, the conserved land in the Amazon rainforest
has almost tripled and deforestation rates have dropped up to 60%. About
1,000,000 square kilometres (250,000,000 acres) have been put onto some
sort of conservation, which adds up to a current amount of 1,730,000
square kilometres (430,000,000 acres).[59]
Anthropogenic emission of greenhouse gases broken down by sector for the year 2000.
Aerosols over the Amazon each September for four burning seasons (2005 through 2008). The aerosol scale (yellow to dark reddish-brown) indicates the relative amount of particles that absorb sunlight.
Aerial roots of red mangrove on an Amazonian river.
A 2009 study found that a 4 °C rise in global temperatures by 2100
would kill 85% of the Amazon rainforest while a temperature rise of 3 °C
would kill some 75% of the Amazon.[60]
Remote sensing
This image reveals how the forest and the atmosphere interact to create a uniform layer of "popcorn-shaped" cumulus clouds.
The use of remotely sensed
data is dramatically improving conservationists' knowledge of the
Amazon basin. Given the objectivity and lowered costs of satellite-based
land cover analysis, it appears likely that remote sensing technology
will be an integral part of assessing the extent and damage of
deforestation in the basin.[61] Furthermore, remote sensing is the best and perhaps only possible way to study the Amazon on a large scale.[62]
The use of remote sensing for the conservation of the Amazon is
also being used by the indigenous tribes of the basin to protect their
tribal lands from commercial interests. Using handheld GPS devices and programs like Google Earth,
members of the Trio Tribe, who live in the rainforests of southern
Suriname, map out their ancestral lands to help strengthen their
territorial claims.[63]
Currently, most tribes in the Amazon do not have clearly defined
boundaries, making it easier for commercial ventures to target their
territories.
To accurately map the Amazon's biomass and subsequent carbon
related emissions, the classification of tree growth stages within
different parts of the forest is crucial. In 2006 Tatiana Kuplich
organized the trees of the Amazon into four categories: (1) mature
forest, (2) regenerating forest [less than three years], (3)
regenerating forest [between three and five years of regrowth], and (4)
regenerating forest [eleven to eighteen years of continued
development].[64] The researcher used a combination of Synthetic aperture radar (SAR) and Thematic Mapper (TM) to accurately place the different portions of the Amazon into one of the four classifications.
Impact of early 21st-century Amazon droughts
In 2005, parts of the Amazon basin experienced the worst drought in one hundred years,[65] and there were indications that 2006 could have been a second successive year of drought.[66] A July 23, 2006 article in the UK newspaper The Independent reported Woods Hole Research Center results showing that the forest in its present form could survive only three years of drought.[67][68] Scientists at the Brazilian National Institute of Amazonian Research
argue in the article that this drought response, coupled with the
effects of deforestation on regional climate, are pushing the rainforest
towards a "tipping point" where it would irreversibly start to die. It concludes that the forest is on the brink of being turned into savanna or desert, with catastrophic consequences for the world's climate.
According to the World Wide Fund for Nature, the combination of climate change and deforestation increases the drying effect of dead trees that fuels forest fires.[69]
In 2010 the Amazon rainforest experienced another severe drought,
in some ways more extreme than the 2005 drought. The affected region
was approximate 1,160,000 square miles (3,000,000 km2) of rainforest, compared to 734,000 square miles (1,900,000 km2)
in 2005. The 2010 drought had three epicenters where vegetation died
off, whereas in 2005 the drought was focused on the southwestern part.
The findings were published in the journal Science. In a typical year
the Amazon absorbs 1.5 gigatons of carbon dioxide; during 2005 instead 5
gigatons were released and in 2010 8 gigatons were released.[70][71] Additional severe droughts occurred in 2010, 2015, and 2016.
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