the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
06 Apr 2021
06 Apr 2021
Global peatlands under future climate – seamless model projections from the Last Glacial Maximum
- 1Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
- 2Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
- 1Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
- 2Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Abstract. Peatlands are diverse wetland ecosystems distributed mostly over the northern latitudes and tropics. Globally they store a large portion of the global soil organic carbon and provide important ecosystem services. The future of these systems under continued anthropogenic warming and direct human disturbance has potentially large impacts on atmospheric CO2 and climate. We performed global long term projections of peatland area and carbon over the next 5000 years using a dynamic global vegetation model forced with climate anomalies from ten models of the Coupled Model Intercomparison Project (CMIP6) and three scenarios. These projections are continued from a transient simulation from the Last Glacial Maximum to the present to account for the full transient history. Our results suggest short to long term net losses of global peatland area and carbon, with higher losses under higher emission scenarios. Large parts of today's active northern peatlands are at risk. Conditions for peatlands in the tropics and, in case of mitigation, eastern Asia and western north America improve. Factorial simulations reveal committed historical changes and future rising temperature as the main driver of future peatland loss and increasing precipitations as driver for regional peatland expansion. Additional simulations forced with two CMIP6 scenarios extended transiently beyond 2100, show qualitatively similar results to the standard scenarios, but highlight the importance of extended future scenarios for long term carbon cycle projections. The spread between simulations forced with different climate model anomalies suggests a large uncertainty in projected peatland variables due to uncertain climate forcing. Our study highlights the importance of quantifying the future peatland feedback to the climate system and its inclusion into future earth system model projections.
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Jurek Müller and Fortunat Joos
Status: closed
-
RC1: 'Comment on bg-2021-80', Anonymous Referee #1, 15 Apr 2021
This study continues to extend a previous study by the same authors of simulating past global peatland dynamics into the future. Novel aspects of the study include the transient nature of the simulations from the previous LGM simulations, the long-term projections of the next few millennia, and the considerations of committed change from legacy changes. This is an important study that contributes to our understanding of long-term trajectories of large peatland carbon stocks.
The manuscript is well written and clearly organized. I have only some editorial suggestions that the authors could consider to improve the presentation.
Specific comments:
Page 1:
Line 1: A possible different title could be:
“Committed and projected future changes in global peatlands—seamless transient model simulations since the Last Glacial Maximum”
These suggested changes because of the following considerations:
-“since” is more clear than “from”, as “from” may need “to”
-“seamless projections from the LGM”: not accurate, as it was not projections per se during most times of the last 21,000 years
-replace “seamless” with more conventional “transient” or “seamless transient”?
-“committed change” is a novel aspect of this study
-“future climate” is only parts of the drivers for change, so “future changes” is broader and more inclusive.
L5: change to “long-term projections”. It is a good style to use hyphen between two nouns when they are used as adjective. For example, “long-term projections”, “land-use conversion/change”, “large-scale restoration”, etc.
L7: change to “three standard future scenarios”, to distinct from “additional” scenarios later on?
L9-10: “Conditions for peatlands …. improve”: the sentence is unclear. What and how?
L10: change to “North America”
L12: these two additional CMIP6 scenarios are part of ten CMIP6 models? Perhaps better to distinct models, simulations and scenarios in the description. There may be the need for explanations of “three scenarios” (are they “standard scenarios”? in what way?) and “additional” “two CMIP6 scenarios”, what the difference? Time durations? If so, spell out in the abstract as well.
L15: change “peatland variables” to some other wordings, such as “peatland changes” or “peatland area and carbon stock”?
L20: change “accumulated organic carbon” to “accumulated organic matter”. Using “matter” (materials) is better here.
Page 2:
L17: change “however” to “, however,”. “however” often needs two commas when in the middle of a sentence, and when connecting two phrases, need “;” before it.
L29: change to “southeast Asia”?
Page 3:
L29 and L34: “, however,”
Page 4:
L2: change “over” to “during”?
L4: “total land area and land-use area”?
L9: use 21,000 years or 22,000 years for LGM, but to be consistent.
L13: Maybe at the end of the Introduction, also describe the general approach of using different scenarios (standard vs. additional).
L17-18: after Joos (2020), change to “, which is described below briefly”
L20: change to “long-term carbon store”
Page 5:
L5: “due to fluctuations/changes in peatland area”?
L15: change “like e.g.” to “such as”
L20: change “like” to “such as”
Page 6:
L1: “, however,”
L9-10: “of actively growing peatlands”
L10-11: change to “… all carbon that have accumulated, including by former peatlands and peatlands transformed to land-use area”
L22: be consistent with the age of the LGM: 22,000 or 21,000 years. See comment above.
L30: change to “a transient land-use history”, otherwise “land use” (no -) if not used to modify another noun
L34: change to “each model of a ten member climate model ensemble”? “member” is unclear here. There are other cases later on.
Page 7:
Figure 1 caption: change “full arrows” to “solid arrow”? Perhaps better to describe as light color rather than “transparent” (as no overlay, transparent is not apparent)
Page 8:
L17: change “sub-sample” to “sub-set”. Throughout the manuscript, perhaps you need to be clear about how to describe the ensemble (22 models in CMIP6), 10 models from this ensemble, and individual model (maybe just call it model, rather than “sample”).
L20: delete “searched and”
L22 and L24: “included in a sample”: ensemble? Group?
Page 9:
Table 1: “Date DOI”: should provide doi instead references?
L16: change “mayor” to “major”
Page 11:
L4: change “land-use and land-use change” to “land use and land-use change”
Page 12:
Headings 3.1 and 3.1.1: change “Historic” to “Historical”
Page 13:
L11-12: Northeastern Canada, East Asia, northwestern Canada, northeastern Asia, Southeast Asia??
L25: change “historical” to “historic”
- AC1: 'Response to reviewer comments', Jurek Müller, 11 May 2021
-
RC2: 'Review of bg-2021-80', Thomas Kleinen, 20 Apr 2021
Review of “Global peatlands under future climate - seamless model projections from the Last Glacial Maximum” by Jurek Müller and Fortunat Joos.
In their manuscript – a follow-on study to their previous publication covering the time from the LGM to the present – Müller & Joos investigate the future evolution of peatlands in the LPX-Bern DGVM. They show and analyse the development of peatlands under a spread of climate forcings from an ensemble of CMIP6 models.
Overall, this is a superb manuscript analysing the future of global peatlands. There are, of course, a few minor issues to resolve, but the manuscript is nearly ready for publication.
Initially I had strong reservations about the manuscript, as the authors only used climate model forcings for the years 1975-2100 in most cases, and 1975-2300 in three cases, while they analysed the peatland development for the next 5000 years. This is not the authors’ fault, as the output from most GCMs in CMIP6 is only available until 2100, very few modelling groups provide extended scenarios until 2300, and none provide output beyond 2300.
Potentially, the repeated climate forcing from the last years data were available might bias results quite strongly. However, experiments we had performed with MPI-ESM for the next millennium confirm that the bias introduced this ways is rather small, as climate remains quite stable after 2300 in most scenarios. Nonetheless, I suggest that the authors elaborate some more on the potential shortcomings of their use of repeated climate anomalies for several millennia. I’d also suggest that the authors put more of a focus on the extended scenario experiments, as the climate forcing changes quite drastically between 2100 and 2300, certainly for the high radiative forcing scenario.
This was the one (semi-) major issue I have with the manuscript. In addition, I was surprised that the authors deal somewhat half-heartedly with one of the most exciting features of their results: The expansion of peatlands after 2700. Yes, it is clear that the criteria for establishment of peatlands must be fulfilled (page 24) – that is implicit in the design of the model – but which ones? What exactly leads to the establishment / growth? Precip increase? Permafrost thaw? NEP increase? If it is too complicated a picture, would a map be possible?
Finally, there are some minor wording suggestions:
- please do a global search and replace changing all instances of “mayor” (German: Bürgermeister) to “major” (German: größer)
- the same goes for historic: Please change to historical
- the authors sometimes mention the “sample members”, for example page 7, line 16, page 8, line 3: I’d suggest to use “ensemble member”, as this is the genrally accepted usage.
- sometimes “at the year XXXX” is used – usually one uses “in the year XXXX”
- page 2, line 1: remove first instance of “global”
- page 2, lines 19 and 32: past tense of “lead” is “led” (I think this also occurred in a few other places)
- page 17, line 24: “main reasons for…” (reason plural, not singular)
- page 17, line 29: particularly strong
- page 20, line 10: latitude instead of latitudinal
- page 23, line 2: “depending on multiple…”
- page 23, line 13: “area than would be” (than instead of as)
- page 23, line 23: “as well as in...”
- page 23, line 33: “scenarios than for the historical…” (than instead of as)
- page 26, line 15: CMIP6, not CIMIP6
- page 27, line 11: “climate change than under pre-industrial” (instead of as)
- page 27, line 34: “mediated different regionally”??? I don’t understand this.
- page 28, line 12: “cause”, not “causes”
- AC2: 'Response to reviewer comments', Jurek Müller, 11 May 2021
Status: closed
-
RC1: 'Comment on bg-2021-80', Anonymous Referee #1, 15 Apr 2021
This study continues to extend a previous study by the same authors of simulating past global peatland dynamics into the future. Novel aspects of the study include the transient nature of the simulations from the previous LGM simulations, the long-term projections of the next few millennia, and the considerations of committed change from legacy changes. This is an important study that contributes to our understanding of long-term trajectories of large peatland carbon stocks.
The manuscript is well written and clearly organized. I have only some editorial suggestions that the authors could consider to improve the presentation.
Specific comments:
Page 1:
Line 1: A possible different title could be:
“Committed and projected future changes in global peatlands—seamless transient model simulations since the Last Glacial Maximum”
These suggested changes because of the following considerations:
-“since” is more clear than “from”, as “from” may need “to”
-“seamless projections from the LGM”: not accurate, as it was not projections per se during most times of the last 21,000 years
-replace “seamless” with more conventional “transient” or “seamless transient”?
-“committed change” is a novel aspect of this study
-“future climate” is only parts of the drivers for change, so “future changes” is broader and more inclusive.
L5: change to “long-term projections”. It is a good style to use hyphen between two nouns when they are used as adjective. For example, “long-term projections”, “land-use conversion/change”, “large-scale restoration”, etc.
L7: change to “three standard future scenarios”, to distinct from “additional” scenarios later on?
L9-10: “Conditions for peatlands …. improve”: the sentence is unclear. What and how?
L10: change to “North America”
L12: these two additional CMIP6 scenarios are part of ten CMIP6 models? Perhaps better to distinct models, simulations and scenarios in the description. There may be the need for explanations of “three scenarios” (are they “standard scenarios”? in what way?) and “additional” “two CMIP6 scenarios”, what the difference? Time durations? If so, spell out in the abstract as well.
L15: change “peatland variables” to some other wordings, such as “peatland changes” or “peatland area and carbon stock”?
L20: change “accumulated organic carbon” to “accumulated organic matter”. Using “matter” (materials) is better here.
Page 2:
L17: change “however” to “, however,”. “however” often needs two commas when in the middle of a sentence, and when connecting two phrases, need “;” before it.
L29: change to “southeast Asia”?
Page 3:
L29 and L34: “, however,”
Page 4:
L2: change “over” to “during”?
L4: “total land area and land-use area”?
L9: use 21,000 years or 22,000 years for LGM, but to be consistent.
L13: Maybe at the end of the Introduction, also describe the general approach of using different scenarios (standard vs. additional).
L17-18: after Joos (2020), change to “, which is described below briefly”
L20: change to “long-term carbon store”
Page 5:
L5: “due to fluctuations/changes in peatland area”?
L15: change “like e.g.” to “such as”
L20: change “like” to “such as”
Page 6:
L1: “, however,”
L9-10: “of actively growing peatlands”
L10-11: change to “… all carbon that have accumulated, including by former peatlands and peatlands transformed to land-use area”
L22: be consistent with the age of the LGM: 22,000 or 21,000 years. See comment above.
L30: change to “a transient land-use history”, otherwise “land use” (no -) if not used to modify another noun
L34: change to “each model of a ten member climate model ensemble”? “member” is unclear here. There are other cases later on.
Page 7:
Figure 1 caption: change “full arrows” to “solid arrow”? Perhaps better to describe as light color rather than “transparent” (as no overlay, transparent is not apparent)
Page 8:
L17: change “sub-sample” to “sub-set”. Throughout the manuscript, perhaps you need to be clear about how to describe the ensemble (22 models in CMIP6), 10 models from this ensemble, and individual model (maybe just call it model, rather than “sample”).
L20: delete “searched and”
L22 and L24: “included in a sample”: ensemble? Group?
Page 9:
Table 1: “Date DOI”: should provide doi instead references?
L16: change “mayor” to “major”
Page 11:
L4: change “land-use and land-use change” to “land use and land-use change”
Page 12:
Headings 3.1 and 3.1.1: change “Historic” to “Historical”
Page 13:
L11-12: Northeastern Canada, East Asia, northwestern Canada, northeastern Asia, Southeast Asia??
L25: change “historical” to “historic”
- AC1: 'Response to reviewer comments', Jurek Müller, 11 May 2021
-
RC2: 'Review of bg-2021-80', Thomas Kleinen, 20 Apr 2021
Review of “Global peatlands under future climate - seamless model projections from the Last Glacial Maximum” by Jurek Müller and Fortunat Joos.
In their manuscript – a follow-on study to their previous publication covering the time from the LGM to the present – Müller & Joos investigate the future evolution of peatlands in the LPX-Bern DGVM. They show and analyse the development of peatlands under a spread of climate forcings from an ensemble of CMIP6 models.
Overall, this is a superb manuscript analysing the future of global peatlands. There are, of course, a few minor issues to resolve, but the manuscript is nearly ready for publication.
Initially I had strong reservations about the manuscript, as the authors only used climate model forcings for the years 1975-2100 in most cases, and 1975-2300 in three cases, while they analysed the peatland development for the next 5000 years. This is not the authors’ fault, as the output from most GCMs in CMIP6 is only available until 2100, very few modelling groups provide extended scenarios until 2300, and none provide output beyond 2300.
Potentially, the repeated climate forcing from the last years data were available might bias results quite strongly. However, experiments we had performed with MPI-ESM for the next millennium confirm that the bias introduced this ways is rather small, as climate remains quite stable after 2300 in most scenarios. Nonetheless, I suggest that the authors elaborate some more on the potential shortcomings of their use of repeated climate anomalies for several millennia. I’d also suggest that the authors put more of a focus on the extended scenario experiments, as the climate forcing changes quite drastically between 2100 and 2300, certainly for the high radiative forcing scenario.
This was the one (semi-) major issue I have with the manuscript. In addition, I was surprised that the authors deal somewhat half-heartedly with one of the most exciting features of their results: The expansion of peatlands after 2700. Yes, it is clear that the criteria for establishment of peatlands must be fulfilled (page 24) – that is implicit in the design of the model – but which ones? What exactly leads to the establishment / growth? Precip increase? Permafrost thaw? NEP increase? If it is too complicated a picture, would a map be possible?
Finally, there are some minor wording suggestions:
- please do a global search and replace changing all instances of “mayor” (German: Bürgermeister) to “major” (German: größer)
- the same goes for historic: Please change to historical
- the authors sometimes mention the “sample members”, for example page 7, line 16, page 8, line 3: I’d suggest to use “ensemble member”, as this is the genrally accepted usage.
- sometimes “at the year XXXX” is used – usually one uses “in the year XXXX”
- page 2, line 1: remove first instance of “global”
- page 2, lines 19 and 32: past tense of “lead” is “led” (I think this also occurred in a few other places)
- page 17, line 24: “main reasons for…” (reason plural, not singular)
- page 17, line 29: particularly strong
- page 20, line 10: latitude instead of latitudinal
- page 23, line 2: “depending on multiple…”
- page 23, line 13: “area than would be” (than instead of as)
- page 23, line 23: “as well as in...”
- page 23, line 33: “scenarios than for the historical…” (than instead of as)
- page 26, line 15: CMIP6, not CIMIP6
- page 27, line 11: “climate change than under pre-industrial” (instead of as)
- page 27, line 34: “mediated different regionally”??? I don’t understand this.
- page 28, line 12: “cause”, not “causes”
- AC2: 'Response to reviewer comments', Jurek Müller, 11 May 2021
Jurek Müller and Fortunat Joos
Data sets
Global peatlands under future climate - seamless model projections from the Last Glacial Maximum: model output data Jurek Müller, Fortunat Joos https://doi.org/10.5281/zenodo.4627681
Jurek Müller and Fortunat Joos
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