Photoluminescence

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Photoluminescence 

Fluorescent solutions under UV light. Absorbed photons are rapidly re-emitted under longer electromagnetic wavelengths.

Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photons that excite electrons to a higher energy level in an atom), hence the prefix photo-. Following excitation, various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary: ranging from short femtosecond-regime for emission involving free-carrier plasma in inorganic semiconductors or metals up to milliseconds for phosphoresence processes in molecular systems; and under special circumstances delay of emission may even span to minutes or hours.

Observation of photoluminescence at a certain energy can be viewed as an indication that an electron transitioned between states separated by this transition energy. While this is generally true in atoms and similar systems, correlations and other more complex phenomena also act as sources for photoluminescence in many-body systems such as semiconductors or metals. A theoretical approach to handle this is given by the semiconductor luminescence equations.

Forms

Schematic for the excitation-relaxation processes of photoluminescence

Photoluminescence processes can be classified by various parameters such as the energy of the exciting photon with respect to the emission. Resonant excitation describes a situation in which photons of a particular wavelength are absorbed and equivalent photons are very rapidly re-emitted. This is often referred to as resonance fluorescence. For materials in solution or in the gas phase, this process involves electrons but no significant internal energy transitions involving molecular features of the chemical substance between absorption and emission. In crystalline inorganic semiconductors where an electronic band structure is formed, secondary emission can be more complicated as events may contain both coherent contributions such as resonant Rayleigh scattering where a fixed phase relation with the driving light field is maintained (i.e. energetically elastic processes where no losses are involved), and incoherent contributions (or inelastic modes where some energy channels into an auxiliary loss mode),

The latter originate, e.g., from the radiative recombination of excitons, Coulomb-bound electron-hole pair states in solids. Resonance fluorescence may also show significant quantum optical correlations.

More processes may occur when a substance undergoes internal energy transitions before re-emitting the energy from the absorption event. Electrons change energy states by either resonantly gaining energy from absorption of a photon or losing energy by emitting photons. In chemistry-related disciplines, one often distinguishes between fluorescence and phosphorescence. The former is typically a fast process, yet some amount of the original energy is dissipated so that re-emitted light photons will have lower energy than did the absorbed excitation photons. The re-emitted photon in this case is said to be red shifted, referring to the reduced energy it carries following this loss (as the Jablonski diagram shows). For phosphorescence, electrons which absorbed photons, undergo intersystem crossing where they enter into a state with altered spin multiplicity (see term symbol), usually a triplet state. Once the excited electron is transferred into this triplet state, electron transition (relaxation) back to the lower singlet state energies is quantum mechanically forbidden, meaning that it happens much more slowly than other transitions. The result is a slow process of radiative transition back to the singlet state, sometimes lasting minutes or hours. This is the basis for "glow in the dark" substances.

Photoluminescence is an important technique for measuring the purity and crystalline quality of semiconductors such as GaN and InP and for quantification of the amount of disorder present in a system.

Time-resolved photoluminescence (TRPL) is a method where the sample is excited with a light pulse and then the decay in photoluminescence with respect to time is measured. This technique is useful for measuring the minority carrier lifetime of III-V semiconductors like gallium arsenide (GaAs).

Photoluminescence properties of direct-gap semiconductors

In a typical PL experiment, a semiconductor is excited with a light-source that provides photons with an energy larger than the bandgap energy. The incoming light excites a polarization that can be described with the semiconductor Bloch equations. Once the photons are absorbed, electrons and holes are formed with finite momenta ${\displaystyle \mathbf{k}}$ in the conduction and valence bands, respectively. The excitations then undergo energy and momentum relaxation towards the band-gap minimum. Typical mechanisms are Coulomb scattering and the interaction with phonons. Finally, the electrons recombine with holes under emission of photons.

Ideal, defect-free semiconductors are many-body systems where the interactions of charge-carriers and lattice vibrations have to be considered in addition to the light-matter coupling. In general, the PL properties are also extremely sensitive to internal electric fields and to the dielectric environment (such as in photonic crystals) which impose further degrees of complexity. A precise microscopic description is provided by the semiconductor luminescence equations.

Ideal quantum-well structures

An ideal, defect-free semiconductor quantum well structure is a useful model system to illustrate the fundamental processes in typical PL experiments. The discussion is based on results published in Klingshirn (2012) and Balkan (1998).

The fictive model structure for this discussion has two confined quantized electronic and two hole subbands, e₁, e₂ and h₁, h₂, respectively. The linear absorption spectrum of such a structure shows the exciton resonances of the first (e1h1) and the second quantum well subbands (e₂, h₂), as well as the absorption from the corresponding continuum states and from the barrier.

Photoexcitation

In general, three different excitation conditions are distinguished: resonant, quasi-resonant, and non-resonant. For the resonant excitation, the central energy of the laser corresponds to the lowest exciton resonance of the quantum well. No, or only a negligible amount of the excess, energy is injected to the carrier system. For these conditions, coherent processes contribute significantly to the spontaneous emission. The decay of polarization creates excitons directly. The detection of PL is challenging for resonant excitation as it is difficult to discriminate contributions from the excitation, i.e., stray-light and diffuse scattering from surface roughness. Thus, speckle and resonant Rayleigh-scattering are always superimposed to the incoherent emission.

In case of the non-resonant excitation, the structure is excited with some excess energy. This is the typical situation used in most PL experiments as the excitation energy can be discriminated using a spectrometer or an optical filter. One has to distinguish between quasi-resonant excitation and barrier excitation.

For quasi-resonant conditions, the energy of the excitation is tuned above the ground state but still below the barrier absorption edge, for example, into the continuum of the first subband. The polarization decay for these conditions is much faster than for resonant excitation and coherent contributions to the quantum well emission are negligible. The initial temperature of the carrier system is significantly higher than the lattice temperature due to the surplus energy of the injected carriers. Finally, only the electron-hole plasma is initially created. It is then followed by the formation of excitons.

In case of barrier excitation, the initial carrier distribution in the quantum well strongly depends on the carrier scattering between barrier and the well.

Relaxation

Initially, the laser light induces coherent polarization in the sample, i.e., the transitions between electron and hole states oscillate with the laser frequency and a fixed phase. The polarization dephases typically on a sub-100 fs time-scale in case of nonresonant excitation due to ultra-fast Coulomb- and phonon-scattering.

The dephasing of the polarization leads to creation of populations of electrons and holes in the conduction and the valence bands, respectively. The lifetime of the carrier populations is rather long, limited by radiative and non-radiative recombination such as Auger recombination. During this lifetime a fraction of electrons and holes may form excitons, this topic is still controversially discussed in the literature. The formation rate depends on the experimental conditions such as lattice temperature, excitation density, as well as on the general material parameters, e.g., the strength of the Coulomb-interaction or the exciton binding energy.

The characteristic time-scales are in the range of hundreds of picoseconds in GaAs; they appear to be much shorter in wide-gap semiconductors.

Directly after the excitation with short (femtosecond) pulses and the quasi-instantaneous decay of the polarization, the carrier distribution is mainly determined by the spectral width of the excitation, e.g., a laser pulse. The distribution is thus highly non-thermal and resembles a Gaussian distribution, centered at a finite momentum. In the first hundreds of femtoseconds, the carriers are scattered by phonons, or at elevated carrier densities via Coulomb-interaction. The carrier system successively relaxes to the Fermi–Dirac distribution typically within the first picosecond. Finally, the carrier system cools down under the emission of phonons. This can take up to several nanoseconds, depending on the material system, the lattice temperature, and the excitation conditions such as the surplus energy.

Initially, the carrier temperature decreases fast via emission of optical phonons. This is quite efficient due to the comparatively large energy associated with optical phonons, (36meV or 420K in GaAs) and their rather flat dispersion, allowing for a wide range of scattering processes under conservation of energy and momentum. Once the carrier temperature decreases below the value corresponding to the optical phonon energy, acoustic phonons dominate the relaxation. Here, cooling is less efficient due their dispersion and small energies and the temperature decreases much slower beyond the first tens of picoseconds. At elevated excitation densities, the carrier cooling is further inhibited by the so-called hot-phonon effect. The relaxation of a large number of hot carriers leads to a high generation rate of optical phonons which exceeds the decay rate into acoustic phonons. This creates a non-equilibrium "over-population" of optical phonons and thus causes their increased reabsorption by the charge-carriers significantly suppressing any cooling. Thus, a system cools slower, the higher the carrier density is.

Radiative recombination

The emission directly after the excitation is spectrally very broad, yet still centered in the vicinity of the strongest exciton resonance. As the carrier distribution relaxes and cools, the width of the PL peak decreases and the emission energy shifts to match the ground state of the exciton (such as an electron) for ideal samples without disorder. The PL spectrum approaches its quasi-steady-state shape defined by the distribution of electrons and holes. Increasing the excitation density will change the emission spectra. They are dominated by the excitonic ground state for low densities. Additional peaks from higher subband transitions appear as the carrier density or lattice temperature are increased as these states get more and more populated. Also, the width of the main PL peak increases significantly with rising excitation due to excitation-induced dephasing and the emission peak experiences a small shift in energy due to the Coulomb-renormalization and phase-filling.

In general, both exciton populations and plasma, uncorrelated electrons and holes, can act as sources for photoluminescence as described in the semiconductor-luminescence equations. Both yield very similar spectral features which are difficult to distinguish; their emission dynamics, however, vary significantly. The decay of excitons yields a single-exponential decay function since the probability of their radiative recombination does not depend on the carrier density. The probability of spontaneous emission for uncorrelated electrons and holes, is approximately proportional to the product of electron and hole populations eventually leading to a non-single-exponential decay described by a hyperbolic function.

Effects of disorder

Real material systems always incorporate disorder. Examples are structural defects in the lattice or disorder due to variations of the chemical composition. Their treatment is extremely challenging for microscopic theories due to the lack of detailed knowledge about perturbations of the ideal structure. Thus, the influence of the extrinsic effects on the PL is usually addressed phenomenologically. In experiments, disorder can lead to localization of carriers and hence drastically increase the photoluminescence life times as localized carriers cannot as easily find nonradiative recombination centers as can free ones.

Researchers from the King Abdullah University of Science and Technology (KAUST) have studied the photoinduced entropy (i.e. thermodynamic disorder) of InGaN/GaN p-i-n double-heterostructure and AlGaN nanowires using temperature-dependent photoluminescence. They defined the photoinduced entropy as a thermodynamic quantity that represents the unavailability of a system's energy for conversion into useful work due to carrier recombination and photon emission. They have also related the change in entropy generation to the change in photocarrier dynamics in the nanowire active regions using results from time-resolved photoluminescence study. They hypothesized that the amount of generated disorder in the InGaN layers eventually increases as the temperature approaches room temperature because of the thermal activation of surface states, while an insignificant increase was observed in AlGaN nanowires, indicating lower degrees of disorder-induced uncertainty in the wider bandgap semiconductor. To study the photoinduced entropy, the scientists have developed a mathematical model that considers the net energy exchange resulting from photoexcitation and photoluminescence.

Photoluminescence from metals

Unlike photoluminescence from semiconductors, photoluminescence from metals is a much weaker effect. In particular, its quantum yield is order of magnitude lower. Nevertheless, metal photoluminecence is of fundamental importance (e.g., for our understanding of electron structure and population dynamics in metals) as well as practical importance (e.g., for thermometry, see next Section).

Photoluminescent materials for temperature detection

In phosphor thermometry, the temperature dependence of the photoluminescence process is exploited to measure temperature. Somewhat similarly, anti-Stokes photoluminescence from metals can be used for thermometry.

Experimental methods

Photoluminescence spectroscopy is a widely used technique for characterisation of the optical and electronic properties of semiconductors and molecules. The technique itself is fast, contactless, and nondestructive. Therefore, it can be used to study the optoelectronic properties of materials of various sizes (from microns to centimeters) during the fabrication process without complex sample preparation. For example, photoluminescence measurements of solar cell absorbers can predict the maximum voltage the material could produce. In chemistry, the method is more often referred to as fluorescence spectroscopy, but the instrumentation is the same. The relaxation processes can be studied using time-resolved fluorescence spectroscopy to find the decay lifetime of the photoluminescence. These techniques can be combined with microscopy, to map the intensity (confocal microscopy) or the lifetime (fluorescence-lifetime imaging microscopy) of the photoluminescence across a sample (e.g. a semiconducting wafer, or a biological sample that has been marked with fluorescent molecules). Modulated photoluminescence is a specific method for measuring the complex frequency response of the photoluminescence signal to a sinusoidal excitation, allowing for the direct extraction of minority carrier lifetime without the need for intensity calibrations. It has been used to study the influence of interface defects on the recombination of excess carriers in crystalline silicon wafers with different passivation schemes.

Green politics

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Green_politics 

Green politics, or ecopolitics, is a political ideology that aims to foster an ecologically sustainable society often, but not always, rooted in environmentalism, nonviolence, social justice and grassroots democracy. It began taking shape in the Western world in the 1970s; since then, green parties have developed and established themselves in many countries around the globe and have achieved some electoral success.

The political term green was used initially in relation to die Grünen (German for "the Greens"), a green party formed in the late 1970s. The term political ecology is sometimes used in academic circles, but it has come to represent an interdisciplinary field of study as the academic discipline offers wide-ranging studies integrating ecological social sciences with political economy in topics such as degradation and marginalization, environmental conflict, conservation and control and environmental identities and social movements.

Supporters of green politics share many ideas with the conservation, environmental, feminist and peace movements. In addition to democracy and ecological issues, green politics is concerned with civil liberties, social justice, nonviolence, sometimes variants of localism and tends to support social progressivism. Green party platforms are largely considered left in the political spectrum. The green ideology has connections with various other ecocentric political ideologies, including ecofeminism, eco-socialism, degrowth and green anarchism, but to what extent these can be seen as forms of green politics is a matter of debate. As the left-wing green political philosophy developed, there also came into separate existence opposite movements on the right-wing that include ecological components such as eco-capitalism and green conservatism.

History

Influences

Mahatma Gandhi

 

Henry David Thoreau, influential early green anarchist who wrote Walden

Adherents to green politics tend to consider it to be part of a higher worldview and not simply a political ideology. Green politics draws its ethical stance from a variety of sources, from the values of indigenous peoples, to the ethics of Mahatma Gandhi, Baruch Spinoza, and Jakob von Uexküll. These people influenced green thought in their advocacy of long-term seventh generation foresight, and on the personal responsibility of every individual to make moral choices.

Unease about adverse consequences of human actions on nature predates the modern concept of environmentalism. Social commentators as far apart as ancient Rome and China complained of air, water and noise pollution.

The philosophical roots of environmentalism can be traced back to enlightenment thinkers such as Rousseau in France, and later the author and naturalist Thoreau in America. Organised environmentalism began in late 19th-century Europe and the United States, as a reaction to the Industrial Revolution with its emphasis on unbridled economic expansion.

"Green politics" first began as conservation and preservation movements, such as the Sierra Club, founded in San Francisco in 1892.

Left-green platforms of the form that make up the green parties today draw terminology from the science of ecology, and policy from environmentalism, deep ecology, feminism, pacifism, anarchism, libertarian socialism, libertarian possibilism, social democracy, eco-socialism, and/or social ecology or green libertarianism. In the 1970s, as these movements grew in influence, green politics arose as a new philosophy which synthesized their goals. The Green Party political movement is not to be confused with the unrelated fact that in some far-right and fascist parties, nationalism has on occasion been tied into a sort of green politics which promotes environmentalism as a form of pride in the "motherland" according to a minority of authors.

Early development

German Green Party co-founder Petra Kelly, first leader and theorist of green politics

 

Marina Silva, influential Brazilian green politician

 

Daniel Cohn-Bendit, contracultural leader of May 1968 events in France

In June 1970, a Dutch group called Kabouters won 5 of the 45 seats on the Amsterdam Gemeenteraad (City Council), as well as two seats each on councils in The Hague and Leeuwarden and one seat apiece in Arnhem, Alkmaar and Leiden. The Kabouters were an outgrowth of Provo's environmental White Plans and they proposed "Groene Plannen" ("Green Plans").

People canvassing for the Values Party, considered the world's first national-level environmentalist party, at Nambassa,1979

The first political party to be created with its basis in environmental issues was the United Tasmania Group, founded in Australia in March 1972 to fight against deforestation and the creation of a dam that would damage Lake Pedder; whilst it only gained three percent in state elections, it inspired the creation of Green parties all over the world. In May 1972, a meeting at Victoria University of Wellington launched the Values Party, the world's first countrywide green party to contest Parliamentary seats nationally. In November 1972, Europe's first green party, PEOPLE in the UK came into existence.

The German Green Party was not the first Green Party in Europe to have members elected nationally but the impression was created that they had been, because they attracted the most media attention: The German Greens, contended in their first national election in the 1980 federal election. They started as a provisional coalition of civic groups and political campaigns which, together, felt their interests were not expressed by the conventional parties. After contesting the 1979 European elections they held a conference which identified Four Pillars of the Green Party which all groups in the original alliance could agree as the basis of a common Party platform: welding these groups together as a single Party. This statement of principles has since been utilised by many Green Parties around the world. It was this party that first coined the term "Green" ("Grün" in German) and adopted the sunflower symbol. The term "Green" was coined by one of the founders of the German Green Party, Petra Kelly, after she visited Australia and saw the actions of the Builders Labourers Federation and their green ban actions. In the 1983 federal election, the Greens won 27 seats in the Bundestag.

Further developments

The first Canadian foray into green politics took place in the Maritimes when 11 independent candidates (including one in Montreal and one in Toronto) ran in the 1980 federal election under the banner of the Small Party. Inspired by Schumacher's Small is Beautiful, the Small Party candidates ran for the expressed purpose of putting forward an anti-nuclear platform in that election. It was not registered as an official party, but some participants in that effort went on to form the Green Party of Canada in 1983 (the Ontario Greens and British Columbia Greens were also formed that year). Green Party of Canada leader Elizabeth May was the instigator and one of the candidates of the Small Party and she was eventually elected as a member of the Green Party in 2011 Canadian federal election.

In Finland, the Green League became the first European Green Party to form part of a state-level Cabinet in 1995. The German Greens followed, forming a government with the Social Democratic Party of Germany (the "Red-Green Alliance") from 1998 to 2005. In 2001, they reached an agreement to end reliance on nuclear power in Germany, and agreed to remain in coalition and support the German government of Chancellor Gerhard Schröder in the 2001 Afghan War. This put them at odds with many Greens worldwide, but demonstrated that they were capable of difficult political tradeoffs.

Sergio Fajardo, ex-mayor of Medellín; Claudia López Hernández, mayor of Bogotá; Joschka Fischer, ex Vice-Chancellor of Germany and Femke Halsema, mayor of Amsterdam

In Latvia, Indulis Emsis, leader of the Green Party and part of the Union of Greens and Farmers, an alliance of a Nordic agrarian party and the Green Party, was Prime Minister of Latvia for ten months in 2004, making him the first Green politician to lead a country in the history of the world. In 2015, Emsis' party colleague, Raimonds Vējonis, was elected President of Latvia by the Latvian parliament. Vējonis became the first green head of state worldwide.

In the German state of Baden-Württenburg, the Green Party became the leader of the coalition with the Social Democrats after finishing second in the 2011 Baden-Württemberg state election. In the following state election, 2016, the Green Party became the strongest party for the first time in a German Landtag.

In 2016, the former leader of the Austrian Greens (1997 to 2008), Alexander Van der Bellen, officially running as an independent, won the 2016 Austrian presidential election, making him the second green head of state worldwide and the first directly elected by popular vote. Van der Bellen placed second in the election's first round with 21.3% of the vote, the best result for the Austrian Greens in their history. He won the second-round run-off against the far-right Freedom Party's Norbert Hofer with 53.8% of the votes, making him the first president of Austria who was not backed by either the People's Party or the Social Democratic Party.

Core tenets

The four green pillars

According to Derek Wall, a prominent British green proponent, there are four pillars that define green politics:

• Ecological wisdom
• Social justice
• Grassroots democracy
• Nonviolence

In 1984, the Green Committees of Correspondence in the United States expanded the Four Pillars into Ten Key Values, which further included:

• Decentralization
• Community-based economics
• Post-patriarchal values (later translated to ecofeminism and Ethics of care)
• Respect for diversity
• Global responsibility
• Future focus

The six guiding principles

In 2001, the Global Greens were organized as an international green movement. The Global Greens Charter identified six guiding principles:

• Ecological wisdom
• Social justice
• Participatory democracy
• Nonviolence
• Sustainability
• Respect for diversity

Ecology

Economics

Main article: Green economics

See also: Communalism (Bookchin), Participatory economics, Post-capitalism, Postgrowth, and Common good (economics)

Green economics focuses on the importance of the health of the biosphere to human well-being. Consequently, most Greens distrust conventional capitalism, as it tends to emphasize economic growth while ignoring ecological health; the "full cost" of economic growth often includes damage to the biosphere, which is unacceptable according to green politics. Green economics considers such growth to be "uneconomic growth"— material increase that nonetheless lowers the overall quality of life. Green economics inherently takes a longer-term perspective than conventional economics, because such a loss in quality of life is often delayed. According to green economics, the present generation should not borrow from future generations, but rather attempt to achieve what Tim Jackson calls "prosperity without growth".

Susan George (political scientist), theorist of social justice and international development

Some Greens refer to productivism, consumerism and scientism as "grey", as contrasted with "green", economic views. "Grey" approaches focus on behavioral changes.

Therefore, adherents to green politics advocate economic policies designed to safeguard the environment. Greens want governments to stop subsidizing companies that waste resources or pollute the natural world, subsidies that Greens refer to as "dirty subsidies". Some currents of green politics place automobile and agribusiness subsidies in this category, as they may harm human health. On the contrary, Greens look to a green tax shift that are seen to encourage both producers and consumers to make ecologically friendly choices.

Many aspects of green economics could be considered anti-globalist. According to many left-wing greens, economic globalization is considered a threat to well-being, which will replace natural environments and local cultures with a single trade economy, termed the global economic monoculture. This is not a universal policy of greens, as green liberals and green conservatives support a regulated free market economy with additional measures to advance sustainable development.

Since green economics emphasizes biospheric health and biodiversity, an issue outside the traditional left-right spectrum, different currents within green politics incorporate ideas from socialism and capitalism. Greens on the Left are often identified as eco-socialists, who merge ecology and environmentalism with socialism and Marxism and blame the capitalist system for environmental degradation, social injustice, inequality and conflict. eco-capitalists, on the other hand, believe that the free market system, with some modification, is capable of addressing ecological problems. This belief is documented in the business experiences of eco-capitalists in the book, The Gort Cloud that describes the gort cloud as the green community that supports eco-friendly businesses.

• 
  Tim Jackson, author of Prosperity Without Growth
   
• 
  François Bausch, member of ATTAC, theorist of the Tobin Tax
   
• 
  Paul Mason, theorist of post-capitalism and universal basic income
   
• 
  Serge Latouche, theorist of degrowth

Participatory democracy

Saskia Sassen, theorist of international Human migration and urban sociology

Since the beginning, green politics has emphasized local, grassroots-level political activity and decision-making. According to its adherents, it is crucial that citizens play a direct role in the decisions that influence their lives and their environment. Therefore, green politics seeks to increase the role of deliberative democracy, based on direct citizen involvement and consensus decision making, wherever it is feasible.

Green politics also encourages political action on the individual level, such as ethical consumerism, or buying things that are made according to environmentally ethical standards. Indeed, many green parties emphasize individual and grassroots action at the local and regional levels over electoral politics. Historically, green parties have grown at the local level, gradually gaining influence and spreading to regional or provincial politics, only entering the national arena when there is a strong network of local support.

In addition, many greens believe that governments should not levy taxes against strictly local production and trade. Some Greens advocate new ways of organizing authority to increase local control, including urban secession, bioregional democracy, and co-operative/local stakeholder ownership.

• 
  Michael Albert, theorist of participatory economics (participism)
   
• 
  César Rendueles, theorist of Common good (economics) and open content and net neutrality
   
• 
  Antonio Negri, theorist of Post-fordism and immaterial labour

Other issues

Anti-Nuclear Power Plant Rally on 19 September 2011 at Meiji Shrine complex in Tokyo in which sixty thousand people marched chanting "Sayonara nuclear power" and waving banners to call on Japan's government to abandon nuclear power following the Fukushima disaster

Although Greens in the United States "call for an end to the 'War on Drugs'" and "for the decriminalization of victimless crimes", they also call for developing "a firm approach to law enforcement that directly addresses violent crime, including trafficking in hard drugs". In Europe, some green parties have tended to support the creation of a democratic federal Europe, while others have opposed European integration.

In the spirit of nonviolence, green politics oppose the war on terrorism and the curtailment of civil rights, focusing instead on nurturing deliberative democracy in war-torn regions and the construction of a civil society with an increased role for women.

In keeping with their commitment to the preservation of diversity, greens are often committed to the maintenance and protection of indigenous communities, languages, and traditions. An example of this is the Irish Green Party's commitment to the preservation of the Irish Language. Some of the green movement has focused on divesting in fossil fuels. Academics Stand Against Poverty states "it is paradoxical for universities to remain invested in fossil fuel companies". Thomas Pogge says that the fossil fuel divestment movement can increase political pressure at events like the international climate change conference (COP). Alex Epstein of Forbes notes that it is hypocritical to ask for divestment without a boycott and that a boycott would be more effective. Some institutions that are leading by example in the academic area are Stanford University, Syracuse University, Sterling College and over 20 more. A number of cities, counties and religious institutions have also joined the movement to divest.

Green politics mostly opposes nuclear fission power and the buildup of persistent organic pollutants, supporting adherence to the precautionary principle, by which technologies are rejected unless they can be proven to not cause significant harm to the health of living things or the biosphere.

Green platforms generally favor tariffs on fossil fuels, restricting genetically modified organisms, and protections for ecoregions or communities.

The Green Party supports phasing out of nuclear power, coal, and incineration of waste. However, the Green Party in Finland has come out against its previous anti-nuclear stance and has stated that addressing global warming in the next 20 years is impossible without expanding nuclear power. These officials have proposed using nuclear-generated heat to heat buildings by replacing the use of coal and biomass to reach zero-emission outputs by 2040.

• 
  Naomi Klein has written about capitalism and climate.
   
• 
  Martha Nussbaum, Professor of Law and Ethics at the University of Chicago, is a proponent of the capabilities approach to animal rights.
   
• 
  Anna Grodzka, Polish green LGBTQIA advocate

Organization

Local movements

The sunflower is recognized internationally as a symbol of green politics.^[]

Green ideology emphasizes participatory democracy and the principle of "thinking globally, acting locally." As such, the ideal Green Party is thought to grow from the bottom up, from neighborhood to municipal to (eco-)regional to national levels. The goal is to rule by a consensus decision making process.

Strong local coalitions are considered a prerequisite to higher-level electoral breakthroughs. Historically, the growth of Green parties has been sparked by a single issue where Greens can appeal to ordinary citizens' concerns. In Germany, for example, the Greens' early opposition to nuclear power won them their first successes in the federal elections.

Global organization

Ashok Khosla was president of the International Union for Conservation of Nature and also worked for the United Nations Environment Programme.

There is a growing level of global cooperation between Green parties. Global gatherings of Green Parties now happen. The first Planetary Meeting of Greens was held 30–31 May 1992, in Rio de Janeiro, immediately preceding the United Nations Conference on Environment and Development held there. More than 200 Greens from 28 nations attended. The first formal Global Greens Gathering took place in Canberra, in 2001, with more than 800 Greens from 72 countries in attendance. The second Global Green Congress was held in São Paulo, Brazil, in May 2008, when 75 parties were represented.

Global Green networking dates back to 1990. Following the Planetary Meeting of Greens in Rio de Janeiro, a Global Green Steering Committee was created, consisting of two seats for each continent. In 1993 this Global Steering Committee met in Mexico City and authorized the creation of a Global Green Network including a Global Green Calendar, Global Green Bulletin, and Global Green Directory. The Directory was issued in several editions in the next years. In 1996, 69 Green Parties from around the world signed a common declaration opposing French nuclear testing in the South Pacific, the first statement of global greens on a current issue. A second statement was issued in December 1997, concerning the Kyoto climate change treaty.

At the 2001 Canberra Global Gathering delegates for Green Parties from 72 countries decided upon a Global Greens Charter which proposes six key principles. Over time, each Green Party can discuss this and organize itself to approve it, some by using it in the local press, some by translating it for their website, some by incorporating it into their manifesto, some by incorporating it into their constitution. This process is taking place gradually, with online dialogue enabling parties to say where they are up to with this process.

Federation of Young European Greens demonstration in Copenhagen during the Climate Summit 2009

The Gatherings also agree on organizational matters. The first Gathering voted unanimously to set up the Global Green Network (GGN). The GGN is composed of three representatives from each Green Party. A companion organization was set up by the same resolution: Global Green Coordination (GGC). This is composed of three representatives from each Federation (Africa, Europe, The Americas, Asia/Pacific, see below). Discussion of the planned organization took place in several Green Parties prior to the Canberra meeting.^[45] The GGC communicates chiefly by email. Any agreement by it has to be by unanimity of its members. It may identify possible global campaigns to propose to Green Parties worldwide. The GGC may endorse statements by individual Green Parties. For example, it endorsed a statement by the US Green Party on the Israel-Palestine conflict.

Thirdly, Global Green Gatherings are an opportunity for informal networking, from which joint campaigning may arise. For example, a campaign to protect the New Caledonian coral reef, by getting it nominated for World Heritage Status: a joint campaign by the New Caledonia Green Party, New Caledonian indigenous leaders, the French Green Party, and the Australian Greens. Another example concerns Ingrid Betancourt, the leader of the Green Party in Colombia, the Green Oxygen Party (Partido Verde Oxigeno). Ingrid Betancourt and the party's Campaign Manager, Claire Rojas, were kidnapped by a hard-line faction of FARC on 7 March 2002, while travelling in FARC-controlled territory. Betancourt had spoken at the Canberra Gathering, making many friends. As a result, Green Parties all over the world have organized, pressing their governments to bring pressure to bear. For example, Green Parties in African countries, Austria, Canada, Brazil, Peru, Mexico, France, Scotland, Sweden and other countries have launched campaigns calling for Betancourt's release. Bob Brown, the leader of the Australian Greens, went to Colombia, as did an envoy from the European Federation, Alain Lipietz, who issued a report. The four Federations of Green Parties issued a message to FARC. Ingrid Betancourt was rescued by the Colombian military in Operation Jaque in 2008.

Global Green Meetings

Separately from the Global Green Gatherings, Global Green Meetings take place. For instance, one took place on the fringe of the World Summit on Sustainable Development in Johannesburg. Green Parties attended from Australia, Taiwan, Korea, South Africa, Mauritius, Uganda, Cameroon, the Republic of Cyprus, Italy, France, Belgium, Germany, Finland, Sweden, Norway, the US, Mexico and Chile.

The Global Green Meeting discussed the situation of Green Parties on the African continent; heard a report from Mike Feinstein, former mayor of Santa Monica, about setting up a website of the GGN; discussed procedures for the better working of the GGC; and decided two topics on which the Global Greens could issue statements in the near future: Iraq and the 2003 WTO meeting in Cancun.

Green federations

Bob Brown at a climate change rally in Melbourne, 5 July 2008

Affiliated members in Asia, Pacific and Oceania form the Asia-Pacific Green Network. The member parties of the Global Greens are organised into four continental federations:

• Federation of Green Parties of Africa
• Federation of the Green Parties of the Americas / Federación de los Partidos Verdes de las Américas
• Asia-Pacific Green Network
• European Green Party

The European Federation of Green Parties formed itself as the European Green Party on 22 February 2004, in the run-up to European Parliament elections in June 2004, a further step in trans-national integration.

Environmental humanities

From Wikipedia, the free encyclopedia

The

Environmental humanities employs humanistic questions about meaning, culture, values, ethics, and responsibilities to address pressing environmental problems. The environmental humanities aim to help bridge traditional divides between the sciences and the humanities, as well as between Western, Eastern, and Indigenous ways of relating to the natural world and the place of humans within it. The field also resists the traditional divide between "nature" and "culture," showing how many "environmental" issues have always been entangled in human questions of justice, labor, and politics. Environmental humanities is also a way of synthesizing methods from different fields to create new ways of thinking through environmental problems.

Emergence of environmental humanities

Although the concepts and ideas underpinning environmental humanities date back centuries, the field consolidated under the name "environmental humanities" in the 2000s following steady developments of the 1970s, 1980s, and 1990s in humanities and social science fields such as literature, history, philosophy, gender studies, and anthropology. A group of Australian researchers used the name "ecological humanities" to describe their work in the 1990s; the field consolidated under the name "environmental humanities" around 2010. The journal Environmental Humanities was founded in 2012 and Resilience: A Journal of the Environmental Humanities in 2014, indicating the development of the field and the consolidation around this terminology.

There are dozens of environmental humanities centers, programs, and institutions around the world. Some of the more prominent ones are the fully funded. Environmental Humanities Graduate Program at the University of Utah, the oldest environmental humanities graduate program in America, the Rachel Carson Center for Environment and Society (RCC) at LMU Munich, the Center for Culture, History, and Environment (CHE) at the University of Wisconsin–Madison, The Center for Energy and Environmental Research in the Human Sciences at Rice University, the Penn Program in Environmental Humanities at the University of Pennsylvania (2014-2024), the KTH Environmental Humanities Laboratory at KTH Royal Institute of Technology, The Greenhouse at the University of Stavanger, and the international Humanities for the Environment observatories.

Dozens of universities offer PhDs, Masters of Arts degrees, graduate certificates, and Bachelor of Arts degrees in environmental humanities. Courses in environmental humanities are taught on every continent.

The environmental humanities did not just emerge from Western academic thinkers: indigenous, postcolonial, and feminist thinkers have provided major contributions. These contributions include challenging the human-centered viewpoints that separate "nature" and "culture" and the white, male, European- and North American-centric viewpoints of what constitutes "nature"; revising the literary genre of "nature writing"; and creating new concepts and fields that bridge the academic and the political, such as "environmental justice," "environmental racism," "the environmentalism of the poor," "naturecultures," and "the posthuman."

Connectivity ontology

The environmental humanities are characterised by a connectivity ontology and a commitment to two fundamental axioms relating to the need to submit to ecological laws and to see humanity as part of a larger living system.

One of the fundamental ontological presuppositions of environmental humanities is that the organic world and its inorganic parts are seen as a single system whereby each part is linked to each other part. This world view in turn shares an intimate connection with Lotka's physiological philosophy and the associated concept of the "World Engine". When we see everything as connected, then the traditional questions of the humanities concerning economic and political justice become enlarged, into a consideration of how justice is connected with our transformation of our environment and ecosystems.

The consequence of such connectivity ontology is, as proponents of the environmental humanities argue, that we begin to seek out a more inclusive concept of justice that includes non-humans within the domain of those to whom rights are owing. This broadened conception of justice involves "enlarged" or "ecological thinking", which presupposes the enhancement of knowledge sharing within fields of plural and diverse ‘knowledges’. This kind of knowledge sharing is called transdisciplinarity. It has links with the political philosophy of Hannah Arendt and the works of Italo Calvino. As Calvino put it, "enlarge[s] the sphere of what we can imagine". It also has connections with Leibniz's Enlightenment project where the sciences are simultaneously abridged while also being enlarged.

The situation is complicated, however, by the recognition of the fact that connections are both non-linear and linear. The environmental humanities, therefore, require both linear and non-linear modes of language through which reasoning about justice can be done. Thus there is a motivation to find linguistic modes which can adequately express both linear and non-linear connectivities.

Axioms

According to some thinkers, there are three axioms of environmental humanities:

1. The axiom of submission to ecosystem laws;
2. The axiom of ecological kinship, which situates humanity as a participant in a larger living system; and
3. The axiom of the social construction of ecosystems and ecological unity, which states that ecosystems and nature may be merely convenient conceptual entities (Marshall, 2002).

Putting the first and second axioms another way, the connections between and among living things are the basis for how ecosystems are understood to work, and thus constitute laws of existence and guidelines for behaviour (Rose 2004).

The first of these axioms has a tradition in social sciences (see Marx, 1968: 3). From the second axiom the notions of "ecological embodiment/ embeddedness" and "habitat" have emerged from Political Theory with a fundamental connectivity to rights, democracy, and ecologism (Eckersley 1996: 222, 225; Eckersley 1998).

The third axiom comes from the strong 'self-reflective' tradition of all 'humanities' scholarship and it encourages the environmental humanities to investigate its own theoretical basis (and without which, the environmental humanities is just 'ecology').

Contemporary ideas

Political economic ecology

See also: Political ecology

Some theorists have suggested that the inclusion of non-humans in the consideration of justice links ecocentric philosophy with political economics. This is because the theorising of justice is a central activity of political economic philosophy. If in accordance with the axioms of environmental humanities, theories of justice are enlarged to include ecological values, then the necessary result is the synthesis of the concerns of ecology with that of political economy: i.e. political economic ecology.

Energy systems language

The question of what language can best depict the linear and non-linear causal connections of ecological systems appears to have been taken up by the school of ecology known as systems ecology. To depict the linear and non-linear internal relatedness of ecosystems where the laws of thermodynamics hold significant consequences (Hannon et al. 1991: 80), Systems Ecologist H.T. Odum (1994) predicated the Energy Systems Language on the principles of ecological energetics. In ecological energetics, just as in environmental humanities, the causal bond between connections is considered an ontic category (see Patten et al. 1976: 460). Moreover, as a result of simulating ecological systems with the energy systems language, H.T. Odum made the controversial suggestion that embodied energy could be understood as value, which in itself is a step into the field of Political Economic Ecology noted above.