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99-611: The Chicago Climate Exchange (CCX) was a voluntary, legally binding greenhouse gas reduction and trading system for emission sources and offset projects in North America and Brazil. CCX employed independent verification, included six greenhouse gases, and traded greenhouse gas emission allowances from 2003 to 2010. The companies joining the exchange committed to reducing their aggregate emissions by 6% by 2010. CCX had an aggregate baseline of 680 million metric tons of CO 2 equivalent . CCX ceased trading carbon credits at
198-563: A medium with matter , their wavelength is decreased. Wavelengths of electromagnetic radiation, whatever medium they are traveling through, are usually quoted in terms of the vacuum wavelength , although this is not always explicitly stated. Generally, electromagnetic radiation is classified by wavelength into radio wave , microwave , infrared , visible light , ultraviolet , X-rays and gamma rays . The behavior of EM radiation depends on its wavelength. When EM radiation interacts with single atoms and molecules , its behavior also depends on
297-425: A radio receiver . Earth's atmosphere is mainly transparent to radio waves, except for layers of charged particles in the ionosphere which can reflect certain frequencies. Radio waves are extremely widely used to transmit information across distances in radio communication systems such as radio broadcasting , television , two way radios , mobile phones , communication satellites , and wireless networking . In
396-422: A radio wave photon that has a wavelength of 21.12 cm. Also, frequencies of 30 Hz and below can be produced by and are important in the study of certain stellar nebulae and frequencies as high as 2.9 × 10 Hz have been detected from astrophysical sources. The types of electromagnetic radiation are broadly classified into the following classes (regions, bands or types): This classification goes in
495-446: A transmitter generates an alternating electric current which is applied to an antenna. The oscillating electrons in the antenna generate oscillating electric and magnetic fields that radiate away from the antenna as radio waves. In reception of radio waves, the oscillating electric and magnetic fields of a radio wave couple to the electrons in an antenna, pushing them back and forth, creating oscillating currents which are applied to
594-573: A carbon credit (termed a CFI or Carbon Financial Instrument) was reached in November 2010 when the carbon credit price per metric ton of CO 2 was between 5 and 10 US cents, down from its highest value of 750 US cents in May 2008. Trading reached zero monthly volume in February 2010 and remained at zero for the next nine months when the decision to close the exchange was announced. The trading system had
693-439: A few meters of water. One notable use is diagnostic X-ray imaging in medicine (a process known as radiography ). X-rays are useful as probes in high-energy physics. In astronomy, the accretion disks around neutron stars and black holes emit X-rays, enabling studies of these phenomena. X-rays are also emitted by stellar corona and are strongly emitted by some types of nebulae . However, X-ray telescopes must be placed outside
792-411: A given year to that year's total emissions. The annual airborne fraction for CO 2 had been stable at 0.45 for the past six decades even as the emissions have been increasing. This means that the other 0.55 of emitted CO 2 is absorbed by the land and atmosphere carbon sinks within the first year of an emission. In the high-emission scenarios, the effectiveness of carbon sinks will be lower, increasing
891-400: A greenhouse gas would absorb over a given time frame after it has been added to the atmosphere (or emitted to the atmosphere). The GWP makes different greenhouse gases comparable with regard to their "effectiveness in causing radiative forcing ". It is expressed as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide (CO 2 ), which is taken as
990-539: A molecule of X remains in the box. τ {\displaystyle \tau } can also be defined as the ratio of the mass m {\displaystyle m} (in kg) of X in the box to its removal rate, which is the sum of the flow of X out of the box ( F out {\displaystyle F_{\text{out}}} ), chemical loss of X ( L {\displaystyle L} ), and deposition of X ( D {\displaystyle D} ) (all in kg/s): If input of this gas into
1089-414: A much shorter atmospheric lifetime than carbon dioxide, its GWP is much less over longer time periods, with a GWP-100 of 27.9 and a GWP-500 of 7.95. The contribution of each gas to the enhanced greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than
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#17327721949511188-445: A process known as water vapor feedback. It occurs because Clausius–Clapeyron relation establishes that more water vapor will be present per unit volume at elevated temperatures. Thus, local atmospheric concentration of water vapor varies from less than 0.01% in extremely cold regions and up to 3% by mass in saturated air at about 32 °C. Global warming potential (GWP) is an index to measure how much infrared thermal radiation
1287-636: A radio communication system, a radio frequency current is modulated with an information-bearing signal in a transmitter by varying either the amplitude, frequency or phase, and applied to an antenna. The radio waves carry the information across space to a receiver, where they are received by an antenna and the information extracted by demodulation in the receiver. Radio waves are also used for navigation in systems like Global Positioning System (GPS) and navigational beacons , and locating distant objects in radiolocation and radar . They are also used for remote control , and for industrial heating. The use of
1386-503: A reference gas. Therefore, the GWP has a value of 1 for CO 2 . For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered. For example, methane has a GWP over 20 years (GWP-20) of 81.2 meaning that, for example, a leak of a tonne of methane is equivalent to emitting 81.2 tonnes of carbon dioxide measured over 20 years. As methane has
1485-408: A single number. Scientists instead say that while the first 10% of carbon dioxide's airborne fraction (not counting the ~50% absorbed by land and ocean sinks within the emission's first year) is removed "quickly", the vast majority of the airborne fraction – 80% – lasts for "centuries to millennia". The remaining 10% stays for tens of thousands of years. In some models, this longest-lasting fraction
1584-491: A variety of Atmospheric Chemistry Observational Databases . The table below shows the most influential long-lived, well-mixed greenhouse gases, along with their tropospheric concentrations and direct radiative forcings , as identified by the Intergovernmental Panel on Climate Change (IPCC). Abundances of these trace gases are regularly measured by atmospheric scientists from samples collected throughout
1683-437: A wave nature or a particle nature with René Descartes , Robert Hooke and Christiaan Huygens favouring a wave description and Newton favouring a particle description. Huygens in particular had a well developed theory from which he was able to derive the laws of reflection and refraction. Around 1801, Thomas Young measured the wavelength of a light beam with his two-slit experiment thus conclusively demonstrating that light
1782-520: Is a CO 2 molecule. The first 30 ppm increase in CO 2 concentrations took place in about 200 years, from the start of the Industrial Revolution to 1958; however the next 90 ppm increase took place within 56 years, from 1958 to 2014. Similarly, the average annual increase in the 1960s was only 37% of what it was in 2000 through 2007. Many observations are available online in
1881-535: Is a level which the Intergovernmental Panel on Climate Change (IPCC) says is "dangerous". Greenhouse gases are infrared active, meaning that they absorb and emit infrared radiation in the same long wavelength range as what is emitted by the Earth's surface, clouds and atmosphere. 99% of the Earth's dry atmosphere (excluding water vapor ) is made up of nitrogen ( N 2 ) (78%) and oxygen ( O 2 ) (21%). Because their molecules contain two atoms of
1980-412: Is able to ionize atoms, causing chemical reactions. Longer-wavelength radiation such as visible light is nonionizing; the photons do not have sufficient energy to ionize atoms. Throughout most of the electromagnetic spectrum, spectroscopy can be used to separate waves of different frequencies, so that the intensity of the radiation can be measured as a function of frequency or wavelength. Spectroscopy
2079-434: Is also cooling the upper atmosphere, as it is much thinner than the lower layers, and any heat re-emitted from greenhouse gases is more likely to travel further to space than to interact with the fewer gas molecules in the upper layers. The upper atmosphere is also shrinking as the result. Anthropogenic changes to the natural greenhouse effect are sometimes referred to as the enhanced greenhouse effect . This table shows
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#17327721949512178-489: Is an asymmetry in electric charge distribution which allows molecular vibrations to interact with electromagnetic radiation. This makes them infrared active, and so their presence causes greenhouse effect . Earth absorbs some of the radiant energy received from the sun, reflects some of it as light and reflects or radiates the rest back to space as heat . A planet's surface temperature depends on this balance between incoming and outgoing energy. When Earth's energy balance
2277-515: Is as large as 30%. Estimates in 2023 found that the current carbon dioxide concentration in the atmosphere may be the highest it has been in the last 14 million years. However the IPCC Sixth Assessment Report estimated similar levels 3 to 3.3 million years ago in the mid-Pliocene warm period . This period can be a proxy for likely climate outcomes with current levels of CO 2 . Greenhouse gas monitoring involves
2376-408: Is called fluorescence . UV fluorescence is used by forensics to detect any evidence like blood and urine, that is produced by a crime scene. Also UV fluorescence is used to detect counterfeit money and IDs, as they are laced with material that can glow under UV. At the middle range of UV, UV rays cannot ionize but can break chemical bonds, making molecules unusually reactive. Sunburn , for example,
2475-722: Is caused by the disruptive effects of middle range UV radiation on skin cells , which is the main cause of skin cancer . UV rays in the middle range can irreparably damage the complex DNA molecules in the cells producing thymine dimers making it a very potent mutagen . Due to skin cancer caused by UV, the sunscreen industry was invented to combat UV damage. Mid UV wavelengths are called UVB and UVB lights such as germicidal lamps are used to kill germs and also to sterilize water. The Sun emits UV radiation (about 10% of its total power), including extremely short wavelength UV that could potentially destroy most life on land (ocean water would provide some protection for life there). However, most of
2574-434: Is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves , microwaves , infrared , visible light , ultraviolet , X-rays , and gamma rays . The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. Radio waves, at
2673-403: Is mostly due to the rapid growth and cumulative magnitude of the disturbances to Earth's carbon cycle by the geologic extraction and burning of fossil carbon. As of year 2014, fossil CO 2 emitted as a theoretical 10 to 100 GtC pulse on top of the existing atmospheric concentration was expected to be 50% removed by land vegetation and ocean sinks in less than about a century, as based on
2772-532: Is not harmless and does create oxygen radicals, mutations and skin damage. After UV come X-rays , which, like the upper ranges of UV are also ionizing. However, due to their higher energies, X-rays can also interact with matter by means of the Compton effect . Hard X-rays have shorter wavelengths than soft X-rays and as they can pass through many substances with little absorption, they can be used to 'see through' objects with 'thicknesses' less than that equivalent to
2871-507: Is shifted, its surface becomes warmer or cooler, leading to a variety of changes in global climate. Radiative forcing is a metric calculated in watts per square meter, which characterizes the impact of an external change in a factor that influences climate. It is calculated as the difference in top-of-atmosphere (TOA) energy balance immediately caused by such an external change. A positive forcing, such as from increased concentrations of greenhouse gases, means more energy arriving than leaving at
2970-489: Is the level the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is "dangerous". Most greenhouse gases have both natural and human-caused sources. An exception are purely human-produced synthetic halocarbons which have no natural sources. During the pre-industrial Holocene , concentrations of existing gases were roughly constant, because the large natural sources and sinks roughly balanced. In
3069-499: Is the most important greenhouse gas overall, being responsible for 41–67% of the greenhouse effect, but its global concentrations are not directly affected by human activity. While local water vapor concentrations can be affected by developments such as irrigation , it has little impact on the global scale due to its short residence time of about nine days. Indirectly, an increase in global temperatures cause will also increase water vapor concentrations and thus their warming effect, in
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3168-494: Is the part of the EM spectrum the human eye is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis. The light that excites the human visual system is a very small portion of the electromagnetic spectrum. A rainbow shows
3267-451: Is too long for ordinary dioxygen in air to absorb. This leaves less than 3% of sunlight at sea level in UV, with all of this remainder at the lower energies. The remainder is UV-A, along with some UV-B. The very lowest energy range of UV between 315 nm and visible light (called UV-A) is not blocked well by the atmosphere, but does not cause sunburn and does less biological damage. However, it
3366-427: Is used to study the interactions of electromagnetic waves with matter. Humans have always been aware of visible light and radiant heat but for most of history it was not known that these phenomena were connected or were representatives of a more extensive principle. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, including reflection and refraction . Light
3465-712: Is warmed by sunlight, causing its surface to radiate heat , which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F). The five most abundant greenhouse gases in Earth's atmosphere, listed in decreasing order of average global mole fraction , are: water vapor , carbon dioxide , methane , nitrous oxide , ozone . Other greenhouse gases of concern include chlorofluorocarbons (CFCs and HCFCs ), hydrofluorocarbons (HFCs), perfluorocarbons , SF 6 , and NF 3 . Water vapor causes about half of
3564-473: The Iowa Farm Bureau to the government-run passenger rail corporation, Amtrak . Greenhouse gas Greenhouse gases ( GHGs ) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits , resulting in the greenhouse effect . The Earth
3663-526: The greenhouse effect is heavily driven by water vapor , human emissions of water vapor are not a significant contributor to warming. The annual "Emissions Gap Report" by UNEP stated in 2022 that it was necessary to almost halve emissions. "To get on track for limiting global warming to 1.5°C, global annual GHG emissions must be reduced by 45 per cent compared with emissions projections under policies currently in place in just eight years, and they must continue to decline rapidly after 2030, to avoid exhausting
3762-963: The radio spectrum is strictly regulated by governments, coordinated by the International Telecommunication Union (ITU) which allocates frequencies to different users for different uses. Microwaves are radio waves of short wavelength , from about 10 centimeters to one millimeter, in the SHF and EHF frequency bands. Microwave energy is produced with klystron and magnetron tubes, and with solid state devices such as Gunn and IMPATT diodes . Although they are emitted and absorbed by short antennas, they are also absorbed by polar molecules , coupling to vibrational and rotational modes, resulting in bulk heating. Unlike higher frequency waves such as infrared and visible light which are absorbed mainly at surfaces, microwaves can penetrate into materials and deposit their energy below
3861-537: The visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions . UV, X-rays, and gamma rays are thus collectively called ionizing radiation ; exposure to them can damage living tissue. UV can also cause substances to glow with visible light; this
3960-456: The > 10 MeV region)—which is of higher energy than any nuclear gamma ray—is not called X-ray or gamma ray, but instead by the generic term of "high-energy photons". The region of the spectrum where a particular observed electromagnetic radiation falls is reference frame -dependent (due to the Doppler shift for light), so EM radiation that one observer would say is in one region of
4059-650: The 7.6 eV (1.22 aJ) nuclear transition of thorium-229m ), and, despite being one million-fold less energetic than some muonic X-rays, the emitted photons are still called gamma rays due to their nuclear origin. The convention that EM radiation that is known to come from the nucleus is always called "gamma ray" radiation is the only convention that is universally respected, however. Many astronomical gamma ray sources (such as gamma ray bursts ) are known to be too energetic (in both intensity and wavelength) to be of nuclear origin. Quite often, in high-energy physics and in medical radiotherapy , very high energy EMR (in
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4158-424: The Earth's atmosphere to see astronomical X-rays, since the great depth of the atmosphere of Earth is opaque to X-rays (with areal density of 1000 g/cm ), equivalent to 10 meters thickness of water. This is an amount sufficient to block almost all astronomical X-rays (and also astronomical gamma rays—see below). After hard X-rays come gamma rays , which were discovered by Paul Ulrich Villard in 1900. These are
4257-478: The Sun's damaging UV wavelengths are absorbed by the atmosphere before they reach the surface. The higher energy (shortest wavelength) ranges of UV (called "vacuum UV") are absorbed by nitrogen and, at longer wavelengths, by simple diatomic oxygen in the air. Most of the UV in the mid-range of energy is blocked by the ozone layer, which absorbs strongly in the important 200–315 nm range, the lower energy part of which
4356-516: The U.S. carbon markets. The market value of the carbon credits had crashed, it was said, because legislation to mandate participation could not pass due to Republican opposition, while others pointed to "a flood of credits from offset project generators." In November 2010, the Climate Exchange stated that it would cease trading carbon credits at the end of 2010, although carbon exchanges will still be facilitated. The effective final value of
4455-504: The amount of energy per quantum (photon) it carries. Spectroscopy can detect a much wider region of the EM spectrum than the visible wavelength range of 400 nm to 700 nm in a vacuum. A common laboratory spectroscope can detect wavelengths from 2 nm to 2500 nm. Detailed information about the physical properties of objects, gases, or even stars can be obtained from this type of device. Spectroscopes are widely used in astrophysics . For example, many hydrogen atoms emit
4554-469: The atmosphere into bodies of water (ocean, lakes, etc.), as well as dissolving in precipitation as raindrops fall through the atmosphere. When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid , which contributes to ocean acidity . It can then be absorbed by rocks through weathering . It also can acidify other surfaces it touches or be washed into the ocean. The vast majority of carbon dioxide emissions by humans come from
4653-427: The atmosphere, terrestrial ecosystems , the ocean, and sediments . These flows have been fairly balanced over the past 1 million years, although greenhouse gas levels have varied widely in the more distant past . Carbon dioxide levels are now higher than they have been for 3 million years. If current emission rates continue then global warming will surpass 2.0 °C (3.6 °F) sometime between 2040 and 2070. This
4752-459: The atmospheric fraction of CO 2 even though the raw amount of emissions absorbed will be higher than in the present. Major greenhouse gases are well mixed and take many years to leave the atmosphere. The atmospheric lifetime of a greenhouse gas refers to the time required to restore equilibrium following a sudden increase or decrease in its concentration in the atmosphere. Individual atoms or molecules may be lost or deposited to sinks such as
4851-423: The balance between sources (emissions of the gas from human activities and natural systems) and sinks (the removal of the gas from the atmosphere by conversion to a different chemical compound or absorption by bodies of water). The proportion of an emission remaining in the atmosphere after a specified time is the " airborne fraction " (AF). The annual airborne fraction is the ratio of the atmospheric increase in
4950-502: The box ceased, then after time τ {\displaystyle \tau } , its concentration would decrease by about 63%. Changes to any of these variables can alter the atmospheric lifetime of a greenhouse gas. For instance, methane's atmospheric lifetime is estimated to have been lower in the 19th century than now, but to have been higher in the second half of the 20th century than after 2000. Carbon dioxide has an even more variable lifetime, which cannot be specified down to
5049-401: The burning of fossil fuels , with remaining contributions from agriculture and industry . Methane emissions originate from agriculture, fossil fuel production, waste, and other sources. The carbon cycle takes thousands of years to fully absorb CO 2 from the atmosphere, while methane lasts in the atmosphere for an average of only 12 years. Natural flows of carbon happen between
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#17327721949515148-405: The burning of fossil fuels . Additional contributions come from cement manufacturing, fertilizer production, and changes in land use like deforestation . Methane emissions originate from agriculture , fossil fuel production, waste, and other sources. If current emission rates continue then temperature rises will surpass 2.0 °C (3.6 °F) sometime between 2040 and 2070, which
5247-844: The chemical mechanisms responsible for photosynthesis and the working of the visual system . The distinction between X-rays and gamma rays is partly based on sources: the photons generated from nuclear decay or other nuclear and subnuclear/particle process are always termed gamma rays, whereas X-rays are generated by electronic transitions involving highly energetic inner atomic electrons. In general, nuclear transitions are much more energetic than electronic transitions, so gamma rays are more energetic than X-rays, but exceptions exist. By analogy to electronic transitions, muonic atom transitions are also said to produce X-rays, even though their energy may exceed 6 megaelectronvolts (0.96 pJ), whereas there are many (77 known to be less than 10 keV (1.6 fJ)) low-energy nuclear transitions ( e.g. ,
5346-635: The commencement of trading in the European Union through the ETS system . The Valley Wood Carbon Sequestration Project, the first such project to be verified through the Chicago Climate Exchange, was the recipient of offset funding generated through a unique partnership, developed in 2008 by Verus Carbon Neutral, that brought together 17 merchants of Atlanta's Virginia-Highland shopping and dining neighborhood retail district to establish
5445-454: The direct measurement of atmospheric concentrations and direct and indirect measurement of greenhouse gas emissions . Indirect methods calculate emissions of greenhouse gases based on related metrics such as fossil fuel extraction. There are several different methods of measuring carbon dioxide concentrations in the atmosphere, including infrared analyzing and manometry . Methane and nitrous oxide are measured by other instruments, such as
5544-436: The electromagnetic spectrum covers the range from roughly 300 GHz to 400 THz (1 mm – 750 nm). It can be divided into three parts: Above infrared in frequency comes visible light . The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. By definition, visible light
5643-809: The electromagnetic spectrum was filled in with the discovery of gamma rays . In 1900, Paul Villard was studying the radioactive emissions of radium when he identified a new type of radiation that he at first thought consisted of particles similar to known alpha and beta particles , but with the power of being far more penetrating than either. However, in 1910, British physicist William Henry Bragg demonstrated that gamma rays are electromagnetic radiation, not particles, and in 1914, Ernest Rutherford (who had named them gamma rays in 1903 when he realized that they were fundamentally different from charged alpha and beta particles) and Edward Andrade measured their wavelengths, and found that gamma rays were similar to X-rays, but with shorter wavelengths. The wave-particle debate
5742-792: The end of 2010 due to inactivity in the U.S. carbon markets, although carbon exchanges were intended to still be facilitated. Until 2010 CCX was operated by the public company Climate Exchange PLC, which also owned the European Climate Exchange . Richard Sandor , creator of the Sustainable Performance Group, founded the exchange and has been a spokesman for it. The exchange traded in emissions of six gases: carbon dioxide , methane , nitrous oxide , sulfur hexafluoride , perfluorocarbons and hydrofluorocarbons . CCX started trading in October 2003, prior to
5841-445: The eyes, this results in visual perception of the scene. The brain's visual system processes the multitude of reflected frequencies into different shades and hues, and through this insufficiently understood psychophysical phenomenon, most people perceive a bowl of fruit. At most wavelengths, however, the information carried by electromagnetic radiation is not directly detected by human senses. Natural sources produce EM radiation across
5940-407: The field. Analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light . This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave. Maxwell's equations predicted an infinite range of frequencies of electromagnetic waves , all traveling at the speed of light. This
6039-606: The first Carbon Neutral Zone in the United States. IntercontinentalExchange ( NYSE : ICE ), a leading operator of regulated global futures exchanges, clearing houses and over-the-counter (OTC) markets, agreed to acquire Climate Exchange plc in January 2009, the acquisition was completed in July 2010 and was followed by an announcement that half of the company's Chicago-based workforce would be laid off due to inactivity in
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#17327721949516138-494: The following three parts. The exchange had more than 400 members ranging from corporations like Ford , DuPont , and Motorola , to state and municipalities such as Oakland and Chicago, to educational institutions such as University of California, San Diego, Tufts University , Michigan State University and University of Minnesota , to farmers and their organizations, such as the National Farmers Union and
6237-403: The following three physical properties: the frequency f , wavelength λ , or photon energy E . Frequencies observed in astronomy range from 2.4 × 10 Hz (1 GeV gamma rays) down to the local plasma frequency of the ionized interstellar medium (~1 kHz). Wavelength is inversely proportional to the wave frequency, so gamma rays have very short wavelengths that are fractions of
6336-446: The greenhouse effect, acting in response to other gases as a climate change feedback . Human activities since the beginning of the Industrial Revolution (around 1750) have increased carbon dioxide by over 50% , and methane levels by 150%. Carbon dioxide emissions are causing about three-quarters of global warming , while methane emissions cause most of the rest. The vast majority of carbon dioxide emissions by humans come from
6435-570: The increasing order of wavelength, which is characteristic of the type of radiation. There are no precisely defined boundaries between the bands of the electromagnetic spectrum; rather they fade into each other like the bands in a rainbow (which is the sub-spectrum of visible light). Radiation of each frequency and wavelength (or in each band) has a mix of properties of the two regions of the spectrum that bound it. For example, red light resembles infrared radiation in that it can excite and add energy to some chemical bonds and indeed must do so to power
6534-506: The industrial era, human activities have added greenhouse gases to the atmosphere, mainly through the burning of fossil fuels and clearing of forests. The major anthropogenic (human origin) sources of greenhouse gases are carbon dioxide (CO 2 ), nitrous oxide ( N 2 O ), methane and three groups of fluorinated gases ( sulfur hexafluoride ( SF 6 ), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs, sulphur hexafluoride (SF 6 ), and nitrogen trifluoride (NF 3 )). Though
6633-455: The limited remaining atmospheric carbon budget ." The report commented that the world should focus on broad-based economy-wide transformations and not incremental change. Several technologies remove greenhouse gas emissions from the atmosphere. Most widely analyzed are those that remove carbon dioxide from the atmosphere, either to geologic formations such as bio-energy with carbon capture and storage and carbon dioxide air capture , or to
6732-425: The low end of the band the atmosphere is mainly transparent, at the upper end of the band absorption of microwaves by atmospheric gases limits practical propagation distances to a few kilometers. Terahertz radiation or sub-millimeter radiation is a region of the spectrum from about 100 GHz to 30 terahertz (THz) between microwaves and far infrared which can be regarded as belonging to either band. Until recently,
6831-525: The low-frequency end of the spectrum, have the lowest photon energy and the longest wavelengths—thousands of kilometers , or more. They can be emitted and received by antennas , and pass through the atmosphere, foliage, and most building materials. Gamma rays, at the high-frequency end of the spectrum, have the highest photon energies and the shortest wavelengths—much smaller than an atomic nucleus . Gamma rays, X-rays, and extreme ultraviolet rays are called ionizing radiation because their high photon energy
6930-708: The most energetic photons , having no defined lower limit to their wavelength. In astronomy they are valuable for studying high-energy objects or regions, however as with X-rays this can only be done with telescopes outside the Earth's atmosphere. Gamma rays are used experimentally by physicists for their penetrating ability and are produced by a number of radioisotopes . They are used for irradiation of foods and seeds for sterilization, and in medicine they are occasionally used in radiation cancer therapy . More commonly, gamma rays are used for diagnostic imaging in nuclear medicine , an example being PET scans . The wavelength of gamma rays can be measured with high accuracy through
7029-828: The most important contributions to the overall greenhouse effect, without which the average temperature of Earth's surface would be about −18 °C (0 °F), instead of around 15 °C (59 °F). This table also specifies tropospheric ozone , because this gas has a cooling effect in the stratosphere , but a warming influence comparable to nitrous oxide and CFCs in the troposphere . K&T (1997) used 353 ppm CO 2 and calculated 125 W/m total clear-sky greenhouse effect; relied on single atmospheric profile and cloud model. "With Clouds" percentages are from Schmidt (2010) interpretation of K&T (1997). Schmidt (2010) used 1980 climatology with 339 ppm CO 2 and 155 W/m total greenhouse effect; accounted for temporal and 3-D spatial distribution of absorbers. Water vapor
7128-550: The optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow whilst ultraviolet would appear just beyond the opposite violet end. Electromagnetic radiation with a wavelength between 380 nm and 760 nm (400–790 terahertz) is detected by the human eye and perceived as visible light. Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when
7227-508: The projections of coupled models referenced in the AR5 assessment. A substantial fraction (20–35%) was also projected to remain in the atmosphere for centuries to millennia, where fractional persistence increases with pulse size. Values are relative to year 1750. AR6 reports the effective radiative forcing which includes effects of rapid adjustments in the atmosphere and at the surface. Atmospheric concentrations are determined by
7326-531: The properties of microwaves . These new types of waves paved the way for inventions such as the wireless telegraph and the radio . In 1895, Wilhelm Röntgen noticed a new type of radiation emitted during an experiment with an evacuated tube subjected to a high voltage . He called this radiation " x-rays " and found that they were able to travel through parts of the human body but were reflected or stopped by denser matter such as bones. Before long, many uses were found for this radiography . The last portion of
7425-522: The range was rarely studied and few sources existed for microwave energy in the so-called terahertz gap , but applications such as imaging and communications are now appearing. Scientists are also looking to apply terahertz technology in the armed forces, where high-frequency waves might be directed at enemy troops to incapacitate their electronic equipment. Terahertz radiation is strongly absorbed by atmospheric gases, making this frequency range useless for long-distance communication. The infrared part of
7524-788: The range-resolved infrared differential absorption lidar (DIAL). Greenhouse gases are measured from space such as by the Orbiting Carbon Observatory and through networks of ground stations such as the Integrated Carbon Observation System . The Annual Greenhouse Gas Index (AGGI) is defined by atmospheric scientists at NOAA as the ratio of total direct radiative forcing due to long-lived and well-mixed greenhouse gases for any year for which adequate global measurements exist, to that present in year 1990. These radiative forcing levels are relative to those present in year 1750 (i.e. prior to
7623-605: The same element , they have no asymmetry in the distribution of their electrical charges , and so are almost totally unaffected by infrared thermal radiation, with only an extremely minor effect from collision-induced absorption . A further 0.9% of the atmosphere is made up by argon (Ar), which is monatomic , and so completely transparent to thermal radiation. On the other hand, carbon dioxide (0.04%), methane , nitrous oxide and even less abundant trace gases account for less than 0.1% of Earth's atmosphere, but because their molecules contain atoms of different elements, there
7722-470: The same mass of carbon dioxide over a 20-year time frame. Since the 1980s, greenhouse gas forcing contributions (relative to year 1750) are also estimated with high accuracy using IPCC-recommended expressions derived from radiative transfer models . The concentration of a greenhouse gas is typically measured in parts per million (ppm) or parts per billion (ppb) by volume. A CO 2 concentration of 420 ppm means that 420 out of every million air molecules
7821-436: The size of atoms , whereas wavelengths on the opposite end of the spectrum can be indefinitely long. Photon energy is directly proportional to the wave frequency, so gamma ray photons have the highest energy (around a billion electron volts ), while radio wave photons have very low energy (around a femtoelectronvolt ). These relations are illustrated by the following equations: where: Whenever electromagnetic waves travel in
7920-455: The soil as in the case with biochar . Many long-term climate scenario models require large-scale human-made negative emissions to avoid serious climate change. Negative emissions approaches are also being studied for atmospheric methane, called atmospheric methane removal . Electromagnetic spectrum The electromagnetic spectrum is the full range of electromagnetic radiation , organized by frequency or wavelength . The spectrum
8019-404: The soil, the oceans and other waters, or vegetation and other biological systems, reducing the excess to background concentrations. The average time taken to achieve this is the mean lifetime . This can be represented through the following formula, where the lifetime τ {\displaystyle \tau } of an atmospheric species X in a one- box model is the average time that
8118-402: The spectrum could appear to an observer moving at a substantial fraction of the speed of light with respect to the first to be in another part of the spectrum. For example, consider the cosmic microwave background . It was produced when matter and radiation decoupled, by the de- excitation of hydrogen atoms to the ground state . These photons were from Lyman series transitions, putting them in
8217-399: The spectrum, and technology can also manipulate a broad range of wavelengths. Optical fiber transmits light that, although not necessarily in the visible part of the spectrum (it is usually infrared), can carry information. The modulation is similar to that used with radio waves. Next in frequency comes ultraviolet (UV). In frequency (and thus energy), UV rays sit between the violet end of
8316-498: The spectrum, as though these were different types of radiation. Thus, although these "different kinds" of electromagnetic radiation form a quantitatively continuous spectrum of frequencies and wavelengths, the spectrum remains divided for practical reasons arising from these qualitative interaction differences. Radio waves are emitted and received by antennas , which consist of conductors such as metal rod resonators . In artificial generation of radio waves, an electronic device called
8415-422: The spectrum, noticed what he called "chemical rays" (invisible light rays that induced certain chemical reactions). These behaved similarly to visible violet light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation. The study of electromagnetism began in 1820 when Hans Christian Ørsted discovered that electric currents produce magnetic fields ( Oersted's law ). Light
8514-521: The start of the industrial era ). 1990 is chosen because it is the baseline year for the Kyoto Protocol , and is the publication year of the first IPCC Scientific Assessment of Climate Change . As such, NOAA states that the AGGI "measures the commitment that (global) society has already made to living in a changing climate. It is based on the highest quality atmospheric observations from sites around
8613-503: The surface. This effect is used to heat food in microwave ovens , and for industrial heating and medical diathermy . Microwaves are the main wavelengths used in radar , and are used for satellite communication , and wireless networking technologies such as Wi-Fi . The copper cables ( transmission lines ) which are used to carry lower-frequency radio waves to antennas have excessive power losses at microwave frequencies, and metal pipes called waveguides are used to carry them. Although at
8712-418: The table. and Annex III of the 2021 IPCC WG1 Report (years) GWP over time up to year 2022 Year 1750 Year 1998 Year 2005 Year 2011 Year 2019 Mole fractions : μmol/mol = ppm = parts per million (10 ); nmol/mol = ppb = parts per billion (10 ); pmol/mol = ppt = parts per trillion (10 ). The IPCC states that "no single atmospheric lifetime can be given" for CO 2 . This
8811-424: The top-of-atmosphere, which causes additional warming, while negative forcing, like from sulfates forming in the atmosphere from sulfur dioxide , leads to cooling. Within the lower atmosphere, greenhouse gases exchange thermal radiation with the surface and limit radiative heat flow away from it, which reduces the overall rate of upward radiative heat transfer. The increased concentration of greenhouse gases
8910-471: The ultraviolet (UV) part of the electromagnetic spectrum. Now this radiation has undergone enough cosmological red shift to put it into the microwave region of the spectrum for observers moving slowly (compared to the speed of light) with respect to the cosmos. Electromagnetic radiation interacts with matter in different ways across the spectrum. These types of interaction are so different that historically different names have been applied to different parts of
9009-421: The visibility to humans is not relevant. White light is a combination of lights of different wavelengths in the visible spectrum. Passing white light through a prism splits it up into the several colours of light observed in the visible spectrum between 400 nm and 780 nm. If radiation having a frequency in the visible region of the EM spectrum reflects off an object, say, a bowl of fruit, and then strikes
9108-431: The waves and was able to infer (by measuring their wavelength and multiplying it by their frequency) that they traveled at the speed of light. Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media , in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin . In a later experiment, Hertz similarly produced and measured
9207-602: The world. It excludes water vapor because changes in its concentrations are calculated as a climate change feedback indirectly caused by changes in other greenhouse gases, as well as ozone, whose concentrations are only modified indirectly by various refrigerants that cause ozone depletion . Some short-lived gases (e.g. carbon monoxide , NOx ) and aerosols (e.g. mineral dust or black carbon ) are also excluded because of limited role and strong variation, along with minor refrigerants and other halogenated gases, which have been mass-produced in smaller quantities than those in
9306-408: The world. Its uncertainty is very low." The natural flows of carbon between the atmosphere, ocean, terrestrial ecosystems , and sediments are fairly balanced; so carbon levels would be roughly stable without human influence. Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres. Carbon dioxide also dissolves directly from
9405-415: Was a wave. In 1800, William Herschel discovered infrared radiation. He was studying the temperature of different colours by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red. He theorized that this temperature change was due to "calorific rays", a type of light ray that could not be seen. The next year, Johann Ritter , working at the other end of
9504-423: Was first linked to electromagnetism in 1845, when Michael Faraday noticed that the polarization of light traveling through a transparent material responded to a magnetic field (see Faraday effect ). During the 1860s, James Clerk Maxwell developed four partial differential equations ( Maxwell's equations ) for the electromagnetic field . Two of these equations predicted the possibility and behavior of waves in
9603-442: Was intensively studied from the beginning of the 17th century leading to the invention of important instruments like the telescope and microscope . Isaac Newton was the first to use the term spectrum for the range of colours that white light could be split into with a prism . Starting in 1666, Newton showed that these colours were intrinsic to light and could be recombined into white light. A debate arose over whether light had
9702-578: Was rekindled in 1901 when Max Planck discovered that light is absorbed only in discrete " quanta ", now called photons , implying that light has a particle nature. This idea was made explicit by Albert Einstein in 1905, but never accepted by Planck and many other contemporaries. The modern position of science is that electromagnetic radiation has both a wave and a particle nature, the wave-particle duality . The contradictions arising from this position are still being debated by scientists and philosophers. Electromagnetic waves are typically described by any of
9801-507: Was the first indication of the existence of the entire electromagnetic spectrum. Maxwell's predicted waves included waves at very low frequencies compared to infrared, which in theory might be created by oscillating charges in an ordinary electrical circuit of a certain type. Attempting to prove Maxwell's equations and detect such low frequency electromagnetic radiation, in 1886, the physicist Heinrich Hertz built an apparatus to generate and detect what are now called radio waves . Hertz found
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