Сценарии rcp это

From Wikipedia, the free encyclopedia

A Representative Concentration Pathway (RCP) is a greenhouse gas concentration (not emissions) trajectory adopted by the IPCC. Four pathways were used for climate modeling and research for the IPCC fifth Assessment Report (AR5) in 2014. The pathways describe different climate futures, all of which are considered possible depending on the volume of greenhouse gases (GHG) emitted in the years to come. The RCPs – originally RCP2.6, RCP4.5, RCP6, and RCP8.5 – are labelled after a possible range of radiative forcing values in the year 2100 (2.6, 4.5, 6, and 8.5 W/m², respectively).^[1][2][3] Since AR5 the original pathways are being considered together with Shared Socioeconomic Pathways: as are new RCPs such as RCP1.9, RCP3.4 and RCP7.^[4]

Concentrations[edit]

The RCPs are consistent with a wide range of possible changes in future anthropogenic (i.e., human) GHG emissions, and aim to represent their atmospheric concentrations.^[5] Despite characterizing RCPs in terms of inputs, a key change from the 2007 to the 2014 IPCC report is that the RCPs ignore the carbon cycle by focusing on concentrations of greenhouse gases, not greenhouse gas inputs.^[6] The IPCC studies the carbon cycle separately, predicting higher ocean uptake of carbon corresponding to higher concentration pathways, but land carbon uptake is much more uncertain due to the combined effect of climate change and land use changes.^[7]

The four RCPs are consistent with certain socio-economic assumptions but are being substituted with the shared socioeconomic pathways which are anticipated to provide flexible descriptions of possible futures within each RCP. The RCP scenarios superseded the Special Report on Emissions Scenarios projections published in 2000 and were based on similar socio-economic models.^[8]

RCPs[edit]

RCP 1.9[edit]

RCP 1.9 is a pathway that limits global warming to below 1.5 °C, the aspirational goal of the Paris Agreement.^[4]

RCP 2.6[edit]

RCP 2.6 is a «very stringent» pathway.^[4]
According to the IPCC, RCP 2.6 requires that carbon dioxide (CO₂) emissions start declining by 2020 and go to zero by 2100. It also requires that methane emissions (CH₄) go to approximately half the CH₄ levels of 2020, and that sulphur dioxide (SO2) emissions decline to approximately 10% of those of 1980–1990. Like all the other RCPs, RCP 2.6 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 2.6, those negative emissions would be on average 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 2.6 is likely to keep global temperature rise below 2 °C by 2100.^[10]

RCP 3.4[edit]

This section needs expansion. You can help by adding to it. (March 2020)

RCP 3.4 represents an intermediate pathway between the «very stringent» RCP2.6 and less stringent mitigation efforts associated with RCP4.5.^[11] As well as just providing another option a variant of RCP3.4 includes considerable removal of greenhouse gases from the atmosphere.^[4]

A 2021 paper suggests that the most plausible projections of cumulative CO₂ emissions (having a 0.1% or 0.3% tolerance with historical accuracy) tend to suggest that RCP 3.4 (3.4 W/m^2, 2.0–2.4 degrees Celsius warming by 2100 according to study) is the most plausible pathway.^[12]

RCP 4.5[edit]

RCP 4.5 is described by the IPCC as an intermediate scenario.^[10] Emissions in RCP 4.5 peak around 2040, then decline.^[13] According to resource specialists IPCC emission scenarios are biased towards exaggerated availability of fossil fuels reserves; RCP 4.5 is the most probable baseline scenario (no climate policies) taking into account the exhaustible character of non-renewable fuels.^[14][15][16]

According to the IPCC, RCP 4.5 requires that carbon dioxide (CO₂) emissions start declining by approximately 2045 to reach roughly half of the levels of 2050 by 2100. It also requires that methane emissions (CH₄) stop increasing by 2050 and decline somewhat to about 75% of the CH₄ levels of 2040, and that sulphur dioxide (SO2) emissions decline to approximately 20% of those of 1980–1990. Like all the other RCPs, RCP 4.5 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 4.5, those negative emissions would be 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 4.5 is more likely than not to result in global temperature rise between 2 °C and 3 °C, by 2100 with a mean sea level rise 35% higher than that of RCP 2.6.^[17] Many plant and animal species will be unable to adapt to the effects of RCP 4.5 and higher RCPs.^[18]

RCP 6[edit]

In RCP 6, emissions peak around 2080, then decline.^[19] The RCP 6.0 scenario uses a high greenhouse gas emission rate and is a stabilisation scenario where total radiative forcing is stabilised after 2100 by employment of a range of technologies and strategies for reducing greenhouse gas emissions. 6.0 W/m² refers to the radiative forcing reached by 2100 Projections for temperature according to RCP 6.0 include continuous global warming through 2100 where CO₂ levels rise to 670 ppm by 2100 making the global temperature rise by about 3–4 °C by 2100.^[20]

RCP 7[edit]

RCP7 is a baseline outcome rather than a mitigation target.^[4]

RCP 8.5[edit]

In RCP 8.5 emissions continue to rise throughout the 21st century.^[13] Since AR5 this has been thought to be very unlikely, but still possible as feedbacks are not well understood.^[21][22] RCP8.5, generally taken as the basis for worst-case climate change scenarios, was based on what proved to be overestimation of projected coal outputs. It is still used for predicting mid-century (and earlier) emissions based on current and stated policies.^[23]

Projections based on the RCPs[edit]

21st century[edit]

Mid- and late-21st century (2046–2065 and 2081–2100 averages, respectively) projections of global warming and global mean sea level rise from the IPCC Fifth Assessment Report (IPCC AR5 WG1) are tabulated below. The projections are relative to temperatures and sea levels in the late-20th to early-21st centuries (1986–2005 average). Temperature projections can be converted to a reference period of 1850–1900 or 1980–99 by adding 0.61 or 0.11 °C, respectively.^[24]

AR5 global warming increase (°C) projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	1.0 (0.4 to 1.6)	1.0 (0.3 to 1.7)
RCP4.5	1.4 (0.9 to 2.0)	1.8 (1.1 to 2.6)
RCP6	1.3 (0.8 to 1.8)	2.2 (1.4 to 3.1)
RCP8.5	2.0 (1.4 to 2.6)	3.7 (2.6 to 4.8)

Across all RCPs, global mean temperature is projected to rise by 0.3 to 4.8 °C by the late 21st century.

According to a 2021 study in which plausible AR5 and SSP scenarios of CO₂ emissions are selected,^[12]

AR5 and SSP Scenarios and temperature change projections

SSP Scenario	Range of Global Mean Temperature Increase (Celsius) – 2100 from pre-Industrial baseline
RCP 1.9	~1 to ~1.5
RCP 2.6	~1.5 to ~2
RCP 3.4	~2 to ~2.4
RCP 4.5	~2.5 to ~3
RCP 6.0	~3 to ~3.5
RCP 7.5	~4
RCP 8.5	~5

AR5 global mean sea level (m) increase projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	0.24 (0.17 to 0.32)	0.40 (0.26 to 0.55)
RCP4.5	0.26 (0.19 to 0.33)	0.47 (0.32 to 0.63)
RCP6	0.25 (0.18 to 0.32)	0.48 (0.33 to 0.63)
RCP8.5	0.30 (0.22 to 0.38)	0.63 (0.45 to 0.82)

Across all RCPs, global mean sea level is projected to rise by 0.26 to 0.82 m by the late-21st century.

23rd century[edit]

AR5 also projects changes in climate beyond the 21st century. The extended RCP2.6 pathway assumes sustained net negative anthropogenic GHG emissions after the year 2070.^[5] «Negative emissions» means that in total, humans absorb more GHGs from the atmosphere than they release. The extended RCP8.5 pathway assumes continued anthropogenic GHG emissions after 2100.^[5] In the extended RCP 2.6 pathway, atmospheric CO₂ concentrations reach around 360 ppmv by 2300, while in the extended RCP8.5 pathway, CO₂ concentrations reach around 2000 ppmv in 2250, which is nearly seven times the pre-industrial level.^[5]

For the extended RCP2.6 scenario, global warming of 0.0 to 1.2 °C is projected for the late-23rd century (2281–2300 average), relative to 1986–2005.^[25] For the extended RCP8.5, global warming of 3.0 to 12.6 °C is projected over the same time period.^[25]

Up to 2500[edit]

In 2021, researchers who found that projecting effects of greenhouse gas emissions only for dates up to 2100 – as widely practiced in research and policy-making – is short-sighted modelled RCP climate change scenarios and their effects for dates up to 2500.^[26][27]

See also[edit]

• Coupled Model Intercomparison Project
• Shared Socioeconomic Pathways

References[edit]

Note: The following references are cited in this article using Template:Harvard citation no brackets:

• IPCC AR5 WG1 (2013), Stocker, T.F.; et al. (eds.), Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Cambridge University Press, archived from the original on 12 August 2014{{citation}}: CS1 maint: bot: original URL status unknown (link). [Archived

• Meinshausen, M.; et al. (November 2011), «The RCP greenhouse gas concentrations and their extensions from 1765 to 2300 (open access)», Climatic Change, 109 (1–2): 213–241, doi:10.1007/s10584-011-0156-z.

External links[edit]

• Special Issue: The representative concentration pathways: an overview, Climatic Change, Volume 109, Issue 1–2, November 2011. Most papers in this issue are freely accessible.
• The Guardian: A guide to the IPCC’s new RCP emissions pathways
• G.P. Wayne: The Beginner’s Guide to Representative Concentration Pathways
• Jubb, I., Canadell, P. and Dix, M. 2013. Representative Concentration Pathways: Australian Climate Change Science Program Information paper

From Wikipedia, the free encyclopedia

A Representative Concentration Pathway (RCP) is a greenhouse gas concentration (not emissions) trajectory adopted by the IPCC. Four pathways were used for climate modeling and research for the IPCC fifth Assessment Report (AR5) in 2014. The pathways describe different climate futures, all of which are considered possible depending on the volume of greenhouse gases (GHG) emitted in the years to come. The RCPs – originally RCP2.6, RCP4.5, RCP6, and RCP8.5 – are labelled after a possible range of radiative forcing values in the year 2100 (2.6, 4.5, 6, and 8.5 W/m², respectively).^[1][2][3] Since AR5 the original pathways are being considered together with Shared Socioeconomic Pathways: as are new RCPs such as RCP1.9, RCP3.4 and RCP7.^[4]

Concentrations[edit]

The RCPs are consistent with a wide range of possible changes in future anthropogenic (i.e., human) GHG emissions, and aim to represent their atmospheric concentrations.^[5] Despite characterizing RCPs in terms of inputs, a key change from the 2007 to the 2014 IPCC report is that the RCPs ignore the carbon cycle by focusing on concentrations of greenhouse gases, not greenhouse gas inputs.^[6] The IPCC studies the carbon cycle separately, predicting higher ocean uptake of carbon corresponding to higher concentration pathways, but land carbon uptake is much more uncertain due to the combined effect of climate change and land use changes.^[7]

The four RCPs are consistent with certain socio-economic assumptions but are being substituted with the shared socioeconomic pathways which are anticipated to provide flexible descriptions of possible futures within each RCP. The RCP scenarios superseded the Special Report on Emissions Scenarios projections published in 2000 and were based on similar socio-economic models.^[8]

RCPs[edit]

RCP 1.9[edit]

RCP 1.9 is a pathway that limits global warming to below 1.5 °C, the aspirational goal of the Paris Agreement.^[4]

RCP 2.6[edit]

RCP 2.6 is a «very stringent» pathway.^[4]
According to the IPCC, RCP 2.6 requires that carbon dioxide (CO₂) emissions start declining by 2020 and go to zero by 2100. It also requires that methane emissions (CH₄) go to approximately half the CH₄ levels of 2020, and that sulphur dioxide (SO2) emissions decline to approximately 10% of those of 1980–1990. Like all the other RCPs, RCP 2.6 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 2.6, those negative emissions would be on average 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 2.6 is likely to keep global temperature rise below 2 °C by 2100.^[10]

RCP 3.4[edit]

This section needs expansion. You can help by adding to it. (March 2020)

RCP 3.4 represents an intermediate pathway between the «very stringent» RCP2.6 and less stringent mitigation efforts associated with RCP4.5.^[11] As well as just providing another option a variant of RCP3.4 includes considerable removal of greenhouse gases from the atmosphere.^[4]

A 2021 paper suggests that the most plausible projections of cumulative CO₂ emissions (having a 0.1% or 0.3% tolerance with historical accuracy) tend to suggest that RCP 3.4 (3.4 W/m^2, 2.0–2.4 degrees Celsius warming by 2100 according to study) is the most plausible pathway.^[12]

RCP 4.5[edit]

RCP 4.5 is described by the IPCC as an intermediate scenario.^[10] Emissions in RCP 4.5 peak around 2040, then decline.^[13] According to resource specialists IPCC emission scenarios are biased towards exaggerated availability of fossil fuels reserves; RCP 4.5 is the most probable baseline scenario (no climate policies) taking into account the exhaustible character of non-renewable fuels.^[14][15][16]

According to the IPCC, RCP 4.5 requires that carbon dioxide (CO₂) emissions start declining by approximately 2045 to reach roughly half of the levels of 2050 by 2100. It also requires that methane emissions (CH₄) stop increasing by 2050 and decline somewhat to about 75% of the CH₄ levels of 2040, and that sulphur dioxide (SO2) emissions decline to approximately 20% of those of 1980–1990. Like all the other RCPs, RCP 4.5 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 4.5, those negative emissions would be 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 4.5 is more likely than not to result in global temperature rise between 2 °C and 3 °C, by 2100 with a mean sea level rise 35% higher than that of RCP 2.6.^[17] Many plant and animal species will be unable to adapt to the effects of RCP 4.5 and higher RCPs.^[18]

RCP 6[edit]

In RCP 6, emissions peak around 2080, then decline.^[19] The RCP 6.0 scenario uses a high greenhouse gas emission rate and is a stabilisation scenario where total radiative forcing is stabilised after 2100 by employment of a range of technologies and strategies for reducing greenhouse gas emissions. 6.0 W/m² refers to the radiative forcing reached by 2100 Projections for temperature according to RCP 6.0 include continuous global warming through 2100 where CO₂ levels rise to 670 ppm by 2100 making the global temperature rise by about 3–4 °C by 2100.^[20]

RCP 7[edit]

RCP7 is a baseline outcome rather than a mitigation target.^[4]

RCP 8.5[edit]

In RCP 8.5 emissions continue to rise throughout the 21st century.^[13] Since AR5 this has been thought to be very unlikely, but still possible as feedbacks are not well understood.^[21][22] RCP8.5, generally taken as the basis for worst-case climate change scenarios, was based on what proved to be overestimation of projected coal outputs. It is still used for predicting mid-century (and earlier) emissions based on current and stated policies.^[23]

Projections based on the RCPs[edit]

21st century[edit]

Mid- and late-21st century (2046–2065 and 2081–2100 averages, respectively) projections of global warming and global mean sea level rise from the IPCC Fifth Assessment Report (IPCC AR5 WG1) are tabulated below. The projections are relative to temperatures and sea levels in the late-20th to early-21st centuries (1986–2005 average). Temperature projections can be converted to a reference period of 1850–1900 or 1980–99 by adding 0.61 or 0.11 °C, respectively.^[24]

AR5 global warming increase (°C) projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	1.0 (0.4 to 1.6)	1.0 (0.3 to 1.7)
RCP4.5	1.4 (0.9 to 2.0)	1.8 (1.1 to 2.6)
RCP6	1.3 (0.8 to 1.8)	2.2 (1.4 to 3.1)
RCP8.5	2.0 (1.4 to 2.6)	3.7 (2.6 to 4.8)

Across all RCPs, global mean temperature is projected to rise by 0.3 to 4.8 °C by the late 21st century.

According to a 2021 study in which plausible AR5 and SSP scenarios of CO₂ emissions are selected,^[12]

AR5 and SSP Scenarios and temperature change projections

SSP Scenario	Range of Global Mean Temperature Increase (Celsius) – 2100 from pre-Industrial baseline
RCP 1.9	~1 to ~1.5
RCP 2.6	~1.5 to ~2
RCP 3.4	~2 to ~2.4
RCP 4.5	~2.5 to ~3
RCP 6.0	~3 to ~3.5
RCP 7.5	~4
RCP 8.5	~5

AR5 global mean sea level (m) increase projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	0.24 (0.17 to 0.32)	0.40 (0.26 to 0.55)
RCP4.5	0.26 (0.19 to 0.33)	0.47 (0.32 to 0.63)
RCP6	0.25 (0.18 to 0.32)	0.48 (0.33 to 0.63)
RCP8.5	0.30 (0.22 to 0.38)	0.63 (0.45 to 0.82)

Across all RCPs, global mean sea level is projected to rise by 0.26 to 0.82 m by the late-21st century.

23rd century[edit]

AR5 also projects changes in climate beyond the 21st century. The extended RCP2.6 pathway assumes sustained net negative anthropogenic GHG emissions after the year 2070.^[5] «Negative emissions» means that in total, humans absorb more GHGs from the atmosphere than they release. The extended RCP8.5 pathway assumes continued anthropogenic GHG emissions after 2100.^[5] In the extended RCP 2.6 pathway, atmospheric CO₂ concentrations reach around 360 ppmv by 2300, while in the extended RCP8.5 pathway, CO₂ concentrations reach around 2000 ppmv in 2250, which is nearly seven times the pre-industrial level.^[5]

For the extended RCP2.6 scenario, global warming of 0.0 to 1.2 °C is projected for the late-23rd century (2281–2300 average), relative to 1986–2005.^[25] For the extended RCP8.5, global warming of 3.0 to 12.6 °C is projected over the same time period.^[25]

Up to 2500[edit]

In 2021, researchers who found that projecting effects of greenhouse gas emissions only for dates up to 2100 – as widely practiced in research and policy-making – is short-sighted modelled RCP climate change scenarios and their effects for dates up to 2500.^[26][27]

See also[edit]

• Coupled Model Intercomparison Project
• Shared Socioeconomic Pathways

References[edit]

Note: The following references are cited in this article using Template:Harvard citation no brackets:

• IPCC AR5 WG1 (2013), Stocker, T.F.; et al. (eds.), Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Cambridge University Press, archived from the original on 12 August 2014{{citation}}: CS1 maint: bot: original URL status unknown (link). [Archived

• Meinshausen, M.; et al. (November 2011), «The RCP greenhouse gas concentrations and their extensions from 1765 to 2300 (open access)», Climatic Change, 109 (1–2): 213–241, doi:10.1007/s10584-011-0156-z.

External links[edit]

• Special Issue: The representative concentration pathways: an overview, Climatic Change, Volume 109, Issue 1–2, November 2011. Most papers in this issue are freely accessible.
• The Guardian: A guide to the IPCC’s new RCP emissions pathways
• G.P. Wayne: The Beginner’s Guide to Representative Concentration Pathways
• Jubb, I., Canadell, P. and Dix, M. 2013. Representative Concentration Pathways: Australian Climate Change Science Program Information paper

From Wikipedia, the free encyclopedia

A Representative Concentration Pathway (RCP) is a greenhouse gas concentration (not emissions) trajectory adopted by the IPCC. Four pathways were used for climate modeling and research for the IPCC fifth Assessment Report (AR5) in 2014. The pathways describe different climate futures, all of which are considered possible depending on the volume of greenhouse gases (GHG) emitted in the years to come. The RCPs – originally RCP2.6, RCP4.5, RCP6, and RCP8.5 – are labelled after a possible range of radiative forcing values in the year 2100 (2.6, 4.5, 6, and 8.5 W/m², respectively).^[1][2][3] Since AR5 the original pathways are being considered together with Shared Socioeconomic Pathways: as are new RCPs such as RCP1.9, RCP3.4 and RCP7.^[4]

Concentrations[edit]

The RCPs are consistent with a wide range of possible changes in future anthropogenic (i.e., human) GHG emissions, and aim to represent their atmospheric concentrations.^[5] Despite characterizing RCPs in terms of inputs, a key change from the 2007 to the 2014 IPCC report is that the RCPs ignore the carbon cycle by focusing on concentrations of greenhouse gases, not greenhouse gas inputs.^[6] The IPCC studies the carbon cycle separately, predicting higher ocean uptake of carbon corresponding to higher concentration pathways, but land carbon uptake is much more uncertain due to the combined effect of climate change and land use changes.^[7]

The four RCPs are consistent with certain socio-economic assumptions but are being substituted with the shared socioeconomic pathways which are anticipated to provide flexible descriptions of possible futures within each RCP. The RCP scenarios superseded the Special Report on Emissions Scenarios projections published in 2000 and were based on similar socio-economic models.^[8]

RCPs[edit]

RCP 1.9[edit]

RCP 1.9 is a pathway that limits global warming to below 1.5 °C, the aspirational goal of the Paris Agreement.^[4]

RCP 2.6[edit]

RCP 2.6 is a «very stringent» pathway.^[4]
According to the IPCC, RCP 2.6 requires that carbon dioxide (CO₂) emissions start declining by 2020 and go to zero by 2100. It also requires that methane emissions (CH₄) go to approximately half the CH₄ levels of 2020, and that sulphur dioxide (SO2) emissions decline to approximately 10% of those of 1980–1990. Like all the other RCPs, RCP 2.6 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 2.6, those negative emissions would be on average 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 2.6 is likely to keep global temperature rise below 2 °C by 2100.^[10]

RCP 3.4[edit]

This section needs expansion. You can help by adding to it. (March 2020)

RCP 3.4 represents an intermediate pathway between the «very stringent» RCP2.6 and less stringent mitigation efforts associated with RCP4.5.^[11] As well as just providing another option a variant of RCP3.4 includes considerable removal of greenhouse gases from the atmosphere.^[4]

A 2021 paper suggests that the most plausible projections of cumulative CO₂ emissions (having a 0.1% or 0.3% tolerance with historical accuracy) tend to suggest that RCP 3.4 (3.4 W/m^2, 2.0–2.4 degrees Celsius warming by 2100 according to study) is the most plausible pathway.^[12]

RCP 4.5[edit]

RCP 4.5 is described by the IPCC as an intermediate scenario.^[10] Emissions in RCP 4.5 peak around 2040, then decline.^[13] According to resource specialists IPCC emission scenarios are biased towards exaggerated availability of fossil fuels reserves; RCP 4.5 is the most probable baseline scenario (no climate policies) taking into account the exhaustible character of non-renewable fuels.^[14][15][16]

According to the IPCC, RCP 4.5 requires that carbon dioxide (CO₂) emissions start declining by approximately 2045 to reach roughly half of the levels of 2050 by 2100. It also requires that methane emissions (CH₄) stop increasing by 2050 and decline somewhat to about 75% of the CH₄ levels of 2040, and that sulphur dioxide (SO2) emissions decline to approximately 20% of those of 1980–1990. Like all the other RCPs, RCP 4.5 requires negative CO₂ emissions (such as CO₂ absorption by trees). For RCP 4.5, those negative emissions would be 2 Gigatons of CO₂ per year (GtCO₂/yr).^[9] RCP 4.5 is more likely than not to result in global temperature rise between 2 °C and 3 °C, by 2100 with a mean sea level rise 35% higher than that of RCP 2.6.^[17] Many plant and animal species will be unable to adapt to the effects of RCP 4.5 and higher RCPs.^[18]

RCP 6[edit]

In RCP 6, emissions peak around 2080, then decline.^[19] The RCP 6.0 scenario uses a high greenhouse gas emission rate and is a stabilisation scenario where total radiative forcing is stabilised after 2100 by employment of a range of technologies and strategies for reducing greenhouse gas emissions. 6.0 W/m² refers to the radiative forcing reached by 2100 Projections for temperature according to RCP 6.0 include continuous global warming through 2100 where CO₂ levels rise to 670 ppm by 2100 making the global temperature rise by about 3–4 °C by 2100.^[20]

RCP 7[edit]

RCP7 is a baseline outcome rather than a mitigation target.^[4]

RCP 8.5[edit]

In RCP 8.5 emissions continue to rise throughout the 21st century.^[13] Since AR5 this has been thought to be very unlikely, but still possible as feedbacks are not well understood.^[21][22] RCP8.5, generally taken as the basis for worst-case climate change scenarios, was based on what proved to be overestimation of projected coal outputs. It is still used for predicting mid-century (and earlier) emissions based on current and stated policies.^[23]

Projections based on the RCPs[edit]

21st century[edit]

Mid- and late-21st century (2046–2065 and 2081–2100 averages, respectively) projections of global warming and global mean sea level rise from the IPCC Fifth Assessment Report (IPCC AR5 WG1) are tabulated below. The projections are relative to temperatures and sea levels in the late-20th to early-21st centuries (1986–2005 average). Temperature projections can be converted to a reference period of 1850–1900 or 1980–99 by adding 0.61 or 0.11 °C, respectively.^[24]

AR5 global warming increase (°C) projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	1.0 (0.4 to 1.6)	1.0 (0.3 to 1.7)
RCP4.5	1.4 (0.9 to 2.0)	1.8 (1.1 to 2.6)
RCP6	1.3 (0.8 to 1.8)	2.2 (1.4 to 3.1)
RCP8.5	2.0 (1.4 to 2.6)	3.7 (2.6 to 4.8)

Across all RCPs, global mean temperature is projected to rise by 0.3 to 4.8 °C by the late 21st century.

According to a 2021 study in which plausible AR5 and SSP scenarios of CO₂ emissions are selected,^[12]

AR5 and SSP Scenarios and temperature change projections

SSP Scenario	Range of Global Mean Temperature Increase (Celsius) – 2100 from pre-Industrial baseline
RCP 1.9	~1 to ~1.5
RCP 2.6	~1.5 to ~2
RCP 3.4	~2 to ~2.4
RCP 4.5	~2.5 to ~3
RCP 6.0	~3 to ~3.5
RCP 7.5	~4
RCP 8.5	~5

AR5 global mean sea level (m) increase projections^[24]

Scenario	2046–2065	2081–2100
Mean (likely range)	Mean (likely range)
RCP2.6	0.24 (0.17 to 0.32)	0.40 (0.26 to 0.55)
RCP4.5	0.26 (0.19 to 0.33)	0.47 (0.32 to 0.63)
RCP6	0.25 (0.18 to 0.32)	0.48 (0.33 to 0.63)
RCP8.5	0.30 (0.22 to 0.38)	0.63 (0.45 to 0.82)

Across all RCPs, global mean sea level is projected to rise by 0.26 to 0.82 m by the late-21st century.

23rd century[edit]

AR5 also projects changes in climate beyond the 21st century. The extended RCP2.6 pathway assumes sustained net negative anthropogenic GHG emissions after the year 2070.^[5] «Negative emissions» means that in total, humans absorb more GHGs from the atmosphere than they release. The extended RCP8.5 pathway assumes continued anthropogenic GHG emissions after 2100.^[5] In the extended RCP 2.6 pathway, atmospheric CO₂ concentrations reach around 360 ppmv by 2300, while in the extended RCP8.5 pathway, CO₂ concentrations reach around 2000 ppmv in 2250, which is nearly seven times the pre-industrial level.^[5]

For the extended RCP2.6 scenario, global warming of 0.0 to 1.2 °C is projected for the late-23rd century (2281–2300 average), relative to 1986–2005.^[25] For the extended RCP8.5, global warming of 3.0 to 12.6 °C is projected over the same time period.^[25]

Up to 2500[edit]

In 2021, researchers who found that projecting effects of greenhouse gas emissions only for dates up to 2100 – as widely practiced in research and policy-making – is short-sighted modelled RCP climate change scenarios and their effects for dates up to 2500.^[26][27]

See also[edit]

• Coupled Model Intercomparison Project
• Shared Socioeconomic Pathways

References[edit]

Note: The following references are cited in this article using Template:Harvard citation no brackets:

• IPCC AR5 WG1 (2013), Stocker, T.F.; et al. (eds.), Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Cambridge University Press, archived from the original on 12 August 2014{{citation}}: CS1 maint: bot: original URL status unknown (link). [Archived

• Meinshausen, M.; et al. (November 2011), «The RCP greenhouse gas concentrations and their extensions from 1765 to 2300 (open access)», Climatic Change, 109 (1–2): 213–241, doi:10.1007/s10584-011-0156-z.

External links[edit]

• Special Issue: The representative concentration pathways: an overview, Climatic Change, Volume 109, Issue 1–2, November 2011. Most papers in this issue are freely accessible.
• The Guardian: A guide to the IPCC’s new RCP emissions pathways
• G.P. Wayne: The Beginner’s Guide to Representative Concentration Pathways
• Jubb, I., Canadell, P. and Dix, M. 2013. Representative Concentration Pathways: Australian Climate Change Science Program Information paper

Андрей Киселев, кандидат физико-математических наук, ведущий научный сотрудник,
Игорь Кароль, профессор, доктор физико-математических наук,
Главная геофизическая обсерватория им. А. И. Воейкова Росгидромета
«Коммерсантъ Наука» №33, август 2019

Современные изменения климата обычно отождествляют с глобальным потеплением. Однако это лишь верхушка айсберга: в климатической системе Земли наряду с ростом температуры происходят и другие не всегда заметные неспециалисту изменения — перестройка циркуляции воздушных масс в атмосфере и воды в Мировом океане, смена режима осадков и др. А эти изменения, в свою очередь, с высокой вероятностью влекут за собой увеличение числа аномальных погодных явлений — ураганов, ливней, засух, длительных периодов с экстремально высокими или низкими температурами.

Оговорка «с высокой вероятностью» здесь необходима, так как имеющихся сегодня данных наблюдений пока недостаточно, чтобы считать связь между изменениями климата и ростом числа погодных катаклизмов надежно установленным научным фактом. К сожалению, общемировая базирующаяся на научных критериях статистика погодных аномалий отсутствует. Отчасти этот пробел восполняет их подсчет, регулярно проводимый крупными страховыми агентствами, но надо учитывать, что у них своя система критериев. Тем не менее общее представление о развитии ситуации в последние десятилетия по данным страховых компаний получить можно.

Триада для объяснения аномалий

За приведенные на рисунке 38 лет число погодных катаклизмов, повлекших за собой значительные материальные потери, возросло примерно в три раза. Поэтому в последние годы изучение этого феномена стало одним из приоритетных направлений климатологии. Достаточно быстро выяснилось, что каждый тип погодных аномалий обладает собственной «индивидуальностью», и его особенности необходимо анализировать отдельно от остальных. Главным образом это вызвано тем обстоятельством, что за возникновение тех или иных погодных катаклизмов «ответственны» разные цепочки развивающихся в климатической системе процессов. Цепочки эти изучены с разной степенью подробности, и это критически отражается на достоверности наших знаний в приложении к каждому отдельному случаю.

Изучение причинно-следственных связей формирования и развития погодных аномалий является комплексным и базируется на «триаде»: 1) на данных их регулярного мониторинга, на способности 2) ясно объяснить происходящее с позиций известных физических законов и 3) воспроизвести его в расчетах с помощью современных климатических моделей. Наличие первых двух пунктов едва ли нуждается в комментариях. А появление третьего необходимо, поскольку только модели могут, во-первых, учесть одновременно все многообразие происходящих в климатической системе взаимодействий, во-вторых, спрогнозировать появление аномалии в обозримом будущем и, в-третьих, восполнить существующий дефицит данных наблюдений.

Атмосфера перестраивается

Согласно современным представлениям, считается, что наибольший прогресс достигнут в понимании механизмов формирования аномальных волн тепла или холода и их связи с текущими изменениями климата. Продолжительность таких волн может составлять от одних или нескольких суток до месяцев (как это было, например, над европейской территорией России летом 2010 года). По данным двух последних десятилетий, наряду с ростом числа летних волн тепла отмечено увеличение их времени жизни. Обычно продолжительное существование таких волн обусловлено блокингом — нахождением над регионом мощного антициклона, препятствующего перемещениям воздушных масс, присущим данной местности и сезону. Подсчитано, что около 3/4 всех блокирующих ситуаций приходится на евразийский континент.

Основной причиной участившихся случаев появления температурных экстремумов называют особенности перестройки атмосферной циркуляции. Однако существуют разные версии относительно того, чем вызвана такая перестройка. Высказывается мнение о ее зависимости от фазы Эль-Ниньо — Южного колебания. Изменения атмосферной циркуляции также объясняют спецификой термодинамических процессов, связывают с нарушениями в струйных течениях, с квазирезонансным усилением, вызывающим высокоамплитудные квазистационарные волны Россби с зональными волновыми числами 6–8 и пр. Столь широкий диапазон толкований, очевидно, стал прямым следствием сложности земной климатической системы, а также нехватки фактических данных. Поэтому неудивительно, что в этой ситуации основная нагрузка ложится на модельную часть вышеупомянутой «триады».

Современные модели высокого разрешения успешно воспроизводят эпизоды возникновения и развития волн тепла или холода, способны прогнозировать их в обозримом будущем. Возникающую при этом проблему описания грядущих изменений климатоформирующих факторов (в первую очередь эволюции эмиссии парниковых газов) решают, используя популярные сегодня сценарии RCP. Не вдаваясь в детали, отметим лишь, что чаще всего выбирают сценарий RCP 8.5, представляющий собой сценарий с максимальными антропогенными выбросами.

Жара может повториться

Основной целью изучения механизмов образования и развития волн тепла или холода (как и других аномальных явлений) является возможность осуществлять в дальнейшем их адекватный модельный прогноз, представляющий практический интерес как для специалистов, так и для обычных людей. Такие прогнозы имеют сегодня широкое распространение и в России, и в мире.

В частности, недавно по проекту Российского научного фонда ученые Главной геофизической обсерватории им. А. И. Воейкова (ГГО) Владимир Катцов, Игорь Школьник и Сергей Ефимов (Перспективные оценки изменений климата в российских регионах: детализация в физическом и вероятностном пространствах // Метеорология и гидрология, № 7, 2017, с. 68–80) оценили будущие изменения экстремальности климата на территории России, в частности, как изменится продолжительность волн тепла и холода к середине и концу текущего столетия.

В ней использовались массовые ансамблевые расчеты с региональной климатической моделью ГГО, охватывающей всю территорию нашей страны с горизонтальным разрешением 25 км, а также сценарий RCP 8.5.

Результаты показаны на рис. 2. Волны тепла (холода) рассчитываются здесь как максимальные за сезон непрерывные периоды (не менее 6 суток) с температурой воздуха у подстилающей поверхности выше (ниже) порогового среднего климатического значения температуры 90-го (10-го) процентиля в данной точке. Рис. 2 свидетельствует, что региональные изменения длительности волн тепла и холода усиливаются в течение XXI века и охватывают почти всю территорию страны к его концу. При этом продолжительность зимних волн холода сокращается гораздо быстрее, нежели растет длительность волн тепла летом.

Исследователи всего мира сегодня сходятся в том, что в ближайшей перспективе в условиях продолжающегося глобального потепления число волн тепла и их продолжительность будут возрастать. Лишь значительное ослабление эмиссии парниковых газов в атмосферу может снизить вероятность появления волн тепла уже в последующие 20 лет. Однако надо быть большим оптимистом, чтобы поверить в реалистичность такого ослабления.

Сценарии

Сравнение опорных сценариев и сценариев стабилизации. Рисунок разделен на шесть частей, по одному на каждую группу опорных сценариев из специального доклада о сценариях выбросов. Каждая часть рисунка показывает диапазон общих глобальных выбросов СО2

(гигатонны углерода (ГтС)) из всех антропогенных источников для группы опорных сценариев СДСВ (затемнение серым цветом) и диапазоны для различных сценариев смягчения последствий и ведущих к стабилизации концентраций СО2 на различных уровнях

(затемнение цветом).

Сценарии представлены для семейства А1, подразделенного на три группы (равновесная группа А1В (рисунок РП-1а), интенсивного использования неископаемых видов топлива А1Т (рисунок РП-1b) и интенсивного использования ископаемых видов топлива А1FI (рисунок РП-1с)) и стабилизации концентраций СО2 на уровнях 450, 550, 650 и 750 ppmv;

Для группы А2 со стабилизацией на уровнях 550 и 750 ppmv на рисунке РП-1d, группы В1 со стабилизацией на уровнях 450 и 550 ppmv на рисунке РП-1е и группы В2 со стабилизацией на уровнях 450, 550 и 650 ppmv на рисунке РП-1f.

В литературе не имеется оценок сценариев стабилизации на уровне 1000 ppmv. Рисунок иллюстрирует тот факт, что чем ниже уровень стабилизации и чем выше исходные уровни выбросов, тем больше расхождение. Различие между выбросами в различных группах сценариев могут быть такими же большими, как и расхождение между опорными сценариями и сценариями стабилизации внутри одной

группы сценариев. Пунктирные линии обозначают границы диапазонов, где они перекрывают друг друга.

1000-1860 гг. – расчет по косвенным данным, красная линия – осреднение температуры за 50 лет, прогноз до 2100г. По 6 сценариям СДСВ и IS92a с использованием модели средней чувствительности климата. Серый участок показывает диапазон результатов полученных с помощью полного набора 35 сценариев СДСВ в дополнении к результатам, полученным на основе моделей с иной чувствительностью климата.

Сценарии (новые)

В проекте CMIP5 вместо известных сценариев SRES (В1, А1В, А2, соответствующих концентрации СО2 в 2100 году в 540, 762 и 875 ppm) по CMIP3,

представлены новые сценарии RCP (Representative Concentration Pathway), связанные со стабилизацией общего антропогенного воздействия в 2100 году также на разных уровнях: 2.6, 4.5, и 8.5 Вт/м2 и вместо концентрации СО2 в ppm в

этих сценариях дан общий эффект воздействия в Вт/м2.

По самому благоприятному сценарию RCP2.6 концентрация СО2 будет такой, что

даст добавку радиационного отклика в 2.6 Вт/м2 к 2100 году по отношению к доиндустриальным условиям. По другим двум неблагоприятным сценариям RCP 6.0 (или rcp60) RCP8.5 (или rcp60) добавка радиационного отклика к 2100 году будет составлять 6.0 Вт/м2 и 8.5 Вт/м2. Каждый из этих 4х основных сценариев имеет и 2 варианта временной экстраполяции: основной – до 2100 г. и его расширение до 2300 г.

Изменение среднегодовой температуры для сценария А2 и В2 СДСВ. Изменения для периода 2071—2100 гг. по отношению к периоду 1961—1999 гг. (основаны на результатах МОЦАО).

Модель ИВМ РАН

Географическое распределение изменения температуры в 2151-2200 гг. по сравнению с 1951-2000 гг.,

За XXI век повышение уровня моря составит до 1 м. В этом случае наиболее уязвимыми окажутся прибрежные территории и небольшие острова. Такие государства как Нидерланды, Великобритания, а также малые островные государства Океании и Карибского бассейна первыми подпадут под опасность затопления. Кроме этого участятся высокие приливы, усилится эрозия береговой линии.

Будущее изменение температуры и осадков в последние 20 лет XXI века по

сравнению со средней температурой периода 1986-2005 гг.

Прогнозируется увеличение стока в высоких широтах и юго- восточной Азии и снижение в центральной части Азии, в районе Средиземноморья, южной части Африки и Австралии.

Прогнозируемые изменения среднего годового стока к 2050 г. по сравнению со средним за 1961-1990 гг. практически полностью совпадают с изменениями в режиме осадков. Оценки получены по модели Хэдли Центра при увеличении концентрации СО2 в атмосфере на 1% в год по вариантам модели: а) усредненный вариант HADCM2, b) HADCM3.

Изменения климата в России в 21 веке (модели CMIP 5) за 2011-2031 гг.

для сценариевRCP2.6 (А), RCP4.5 (Б) и RCP8.5 (В) по температуре воздуха.