US-Russia summit talks, talks themselves are useful without agreement = Russian president's aides
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Nuclear issues, climate change, cybersecurity, etc. are expected to be on the agenda.
[Moscow, XNUMXth Reuters] – Russian President Vladimir Putin's diplomatic adviser, Yuri Ushakov, said ... → Continue reading
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Climate change(Kikouhendo,British: climatic variation) Is at various time scales,temperature,Precipitation amount,(I.e.It is widely used as a term indicating changes such as. EspeciallyEnvironment issuesIn the context of地球Phenomenon that the surface temperature ofGlobal warmingAnd its effects are often collectively referred to as climate change.
In terms of meteorology, the phenomenon that the average climate of a normal year changes on a long-term time scale is the climate.changeIt is called (climate change). climateFluctuation(Climatic variation) is used to mean the deviation from the average climate of a normal year, and is distinguished from climate change..
However, in recent years, there are cases where two terms are mixed and used, or different terms are used based on their own definitions. For example,United NationsUNFCCC (Framework Convention on Climate Change), the term "climate change" is used for artificial changes and "climate variability" is used for non-artificial changes.In addition,IPCCThe same term "climate change" is used to describe both anthropogenic and non-artificial changes collectively in the Japanese version, and in the Japanese translation, it is written as climate change (as a term that includes "climate change").. (IPCC Fourth Assessment Report#Notation used(See also)
Factors that change the climate
Factors that determine the global climate include those internal to the climate system and external coercive forces from outside the system. In the climate system, the atmosphere and ocean interact according to the laws of physics. Caused by air-sea interactionEl Nino-Southern OscillationIs the variation inherent in the climate system. on the other hand,Fluctuations in solar activity, Changes in the Earth's orbit,volcanic eruptionbyaerosolincrease of,Sea salt particlesThe generation of soil aerosol (dust) is an external force due to natural factors.Greenhouse gasThere are also external forcings derived from human activities, such as emissions of air and pollutants, deforestation and changes in land use.
The following are examples of climate change and its factors.
- Glacial and interglacialChanges in the 10 year cycle, and 4 and 2 year changes between the subglacial and interglacialChanges in orbital elementsCaused by (external force).
- Ice sheet coreThe results of seafloor sediment surveys have revealed that the temperature has changed drastically over a period of 1 years or less. this isBond cycleIt is thought to reflect the formation and collapse of ice sheets such as (a factor inherent in the climate system).
- Little Ice Age TheSolar radiationIt is thought to have been caused by changes in volcanic activity, or a combination of both (external forcing).
If a factor changes the climate, and that change amplifies the effect of the factor, the climatePositivefeedbackI think that it has a mechanism to cause. On the contrary, when it attenuatesNegative feedbackIs equipped with. Since there is a strong negative feedback of increase in radiant energy due to temperature rise, it is considered that positive feedback is unlikely to runaway even if global warming progresses. .. The feedback mechanism is discussed in more detail in Chapter 3 of the IPCC Third Report (Part 1)... However, there are many positive feedback mechanisms, such as carbon dioxide emission from permafrost, which are currently unknown..
The following are examples of positive feedback effects.
- Ice-reflectance and feedback
- Ice and snow that cover the surface of the earth have a high reflectance of sunlight, but the ground and the sea surface below it have a low reflectance and tend to absorb sunlight and become warm. When ice or snow melts, the exposed parts of the ground and sea surface increase, so sunlight is more easily absorbed and the temperature rises, and the ice and snow melts further... As a typical oneArctic OceanMelting of sea iceBy seawaterSun lightIncreased absorption has been widely reported in recent years..
- permafrostCarbon dioxide emission from
- The permafrost melts as the temperature rises, and the decomposition of the trapped organic mattercarbon dioxideIt has been pointed out that the release of γ will contribute to positive feedback. So far, these polar territories are allegedly likely to be slightly carbon sinks overall, but the process of carbon release is complex and the uncertainty of this conclusion is high..
- Role of carbon dioxide in the 10-year glacial/interglacial cycle
- This cycle isOrbital elementThe effect is too small, and it is generally believed that changes in carbon dioxide enhance the signal.
One of the negative feedback effects is the absorption of carbon dioxide from the atmosphere on the surface and ocean,BiosphereThere is a natural storage such as. Due to the existence of this level of feedback effect, it is easy to predict that carbon dioxide emitted into the atmosphere is only of human origin, but the relationship between changes in temperature and carbon dioxide levels in the atmosphere is explained. Is difficult. For example, it is not possible to conclude that it is negative, and there is a possibility that it will work positively because there is a possibility that carbon in soil will decrease due to rising temperature and climate change will reduce tropical rainforests. Regarding the negative feedback effect of organismsBiological pumpThe hypothesis is known.
Factors of natural origin
Obviously, external factors of natural origin are as important as internal factors have played an important role in past climate change.
Change in solar radiation
The most important external factors of nature are(I.e.Although it is a change in radiation due to activity, the amount of solar radiation reaching the earth is not geographically or temporally uniform. Solar radiation changes on a short time scale (about 11 years) depending on the solar cycle, and changes on a scale of 100 to 1000 years due to periodic changes in the earth's orbit. Considering it for a long time (1 million years), the phenomenon that the sun itself becomes hot is added.
Several other mechanisms have been proposed as factors that influence celestial activity on global climate change. For example,Equatorial quasi-biennial oscillation(QBO: quasi-biennial oscillation) And solar activity,Arctic oscillation(AO: arctic oscillation) and solar activityAnd so on. Of the moonTidal forceChange ofエ ル ニ ー ニ ョ,La NiñaIt has been pointed out that the relationship with.. This is the tidal force of the moonHot salt circulationIt is also said to affect.
The Earth's current atmosphere has a carbon dioxide (CO2) concentration of 370 ppm (0.037%), but for most of the last 6 million years, the concentration of carbon dioxide in the atmosphere has fluctuated between 6000 and 400 ppm. Was lower than 40ppm in the last 300 years (before the industrial revolution)(Graphic of carbon dioxide in the Phanerozoic atmosphere and average temperatureSee also). Compared with the past geological era, carbon dioxide in the present atmosphere is very low (). In the history of the earth from 6 million years ago to the present, the carbon dioxide concentration is 400 ppm or less,CarboniferousAnd the currentQuaternaryOnly.
Examples of changes due to natural origin
Ice age/InterglacialThe 10-year cycle is an example of changes due to natural external factors. Two relatively widespread events over the last 1000 years, with relatively warm temperaturesMedieval warm seasonWas coldLittle Ice AgeThese changes were caused by natural causes, since the human factors are considered to be small in that era. The Little Ice Age is thought to be due to a decline in solar activity or an increase in volcanic activity, but it is not yet clear about the Middle Ages warm period. A few researchers argue that the warming that has been occurring since 1860 may be due to a natural cause of the recovery process from the Little Ice Age..
Factors resulting from human activities
Anthropogenic factors are humankind (Homo sapiens) Refers to activities. The largest are carbon dioxide released in large quantities in the process of burning fossil fuels since the Industrial Revolution in Europe, most of which was emitted after 1945. Other factors include deforestation, land surfaceAlbedoChanges in agriculture and other land uses, effects on carbon cycle and methane production, and emission of man-made aerosols.
Anthropogenic greenhouse gas
One of the major human factors isGreenhouse gasAnd the increase in emissions isGreenhouse effectBringIndustrial revolutionSince the beginning of, a large amount of anthropogenic greenhouse gases have been released into the atmosphere. Since 1750, the IPCC has increased carbon dioxide concentration by 31%, methane by 151%, nitrogen oxides by 17%, and tropospheric ozone by 36%.Fossil fuelIt is produced by burning. Methane gas is also increased in livestock, fuel, and rice production, and is about 66% of the amount released from wetlands due to natural factors.Was announced.
Evaluation of the relative importance of various factors
The relative importance of each of the proposed options depends on the time of interest, for example, anthropogenic factors are expected to be insignificant for pre-1750 climate change. However, this is recently reported by Ruddiman et al.Arguing that the deforestation and rice cultivation from 8000 years ago have increased carbon dioxide and methane levels. Schmidt et al. refute this, saying that the methane record is unlikely to have artificial significance.
Anyway, its importance can be assessed through quantification of the factors involved. Better response of internal factors to external factorsClimate modelIt can be estimated by climate simulation using.
The influence of external factorsRadiative forcingIt is compared with the idea. If the radiative forcing works positively on the planet, it causes warming, and if it works negatively, it causes cooling. The unit is the work amount per area W/m2.IPCC'S third report summarizes the impact of radiative forcing on the current climate..
Impact of global warming
- Sea level fluctuation -About sea level rise
- Glacier melting(Glacier retreat)
- Impact on environment and ecosystem
Addressing climate change
- Global activities
It was held in Berlin, Germany on March 1995, 3, and was held in Kyoto in December 28.3th Conference of the Parties to the United Nations Framework Convention on Climate ChangeIs a Framework Convention on Climate ChangeKyoto ProtocolWas adopted. Change to the Kyoto Protocol in November 2015Paris Agreement 21th Conference of the Parties to the United Nations Framework Convention on Climate ChangeAdopted by.
,Is also being done.Also, from September 2019th to 9th, just before the 20 United Nations Climate Change Summit.Global Climate March(2019 Climate Change Strike) was called and demonstrations were held all over the world.
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- ^ a b IPCC Technical Papers II and III, February 1997
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- IPCC Fourth Assessment Report Working Group 4 Report Summary for Policymakers
- IPCC Fourth Assessment Report
- IPCC WG1 AR4 Final Report
- Scientists facing the mainstream scientific assessment of global warming
- Climate change and adaptation ecosci.jp (living environment chemistry room)