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Modeling long-term carbon dynamics for High Arctic dry and wet ecosystems

Christiansen, Lasse LU (2025) In Student thesis series INES NGEM01 20251
Dept of Physical Geography and Ecosystem Science
Abstract
Climate change is intensifying globally, leading to rising temperatures. The Arctic being a vulnerable and extreme environment faces an enhanced warming effect, referred to as the Arctic amplification. In this rapidly changing environment, high amounts of carbon (1,460 – 1,600 Pg C) are stored in permafrost. This is four times the amount of carbon being emitted by humans in modern times. Increasing temperatures are changing fragile Arctic ecosystems, leading to permafrost thaw and change of vegetation. This will affect local carbon emission dynamics further enhancing climate change.
To assess future greenhouse gas emissions in a High-Arctic setting, the dynamic global vegetation model LPJ-GUESS was used to simulate GHG emissions. To... (More)
Climate change is intensifying globally, leading to rising temperatures. The Arctic being a vulnerable and extreme environment faces an enhanced warming effect, referred to as the Arctic amplification. In this rapidly changing environment, high amounts of carbon (1,460 – 1,600 Pg C) are stored in permafrost. This is four times the amount of carbon being emitted by humans in modern times. Increasing temperatures are changing fragile Arctic ecosystems, leading to permafrost thaw and change of vegetation. This will affect local carbon emission dynamics further enhancing climate change.
To assess future greenhouse gas emissions in a High-Arctic setting, the dynamic global vegetation model LPJ-GUESS was used to simulate GHG emissions. To reduce uncertainty in future climate simulations, three different climate models were used under two different shared socio-economic pathways (SSP1-2.6 and SSP5-8.5). The study was conducted with two different settings, a dry and wet ecosystem in a High Arctic location. The dry ecosystem was compared to a cassiope heath, and the wet to a fen at the Zackenberg research station in Northeast Greenland. The model significantly underestimates CO2 and CH4 fluxes compared to observations. Carbon dioxide emissions are underestimated due to plant absence. Underestimated methane emissions are likely caused by the lack of simulating soil warming processes. In addition, too few simulated plants result in limited litter input and therefore less carbon available in the soil for methane production. Different versions of the model LPJ-GUESS might improve modeling performance. In addition, vegetation and soil properties and dynamics are suggested to be adapted to the well adapted High Arctic environment. Adapting the simulation attempt is highly important in order to simulate future greenhouse gas emissions accurately and give estimates of greenhouse gas dynamics of this carbon rich environment. (Less)
Abstract (Danish)
Klimaforandringerne intensiveres globalt og fører til stigende temperaturer. Arktis, som er et sårbart og ekstremt miljø, står over for en forstærket opvarmningseffekt, kaldet den arktiske forstærkning. I dette hurtigt skiftende miljø lagres store mængder kulstof (1,460 – 1,600 Pg C) i permafrosten. Det er fire gange mere end den mængde kulstof, som mennesker har udledt i moderne tid. Stigende temperaturer ændrer de skrøbelige arktiske økosystemer, hvilket fører til optøning af permafrosten og ændringer i vegetationen. Det påvirker den lokale kulstofudledningsdynamik og forstærke klimaforandringerne yderligere.
For at vurdere fremtidige drivhusgassemissioner i højarktiske omgivelser blev den dynamiske globale vegetationsmodel LPJ-GUESS... (More)
Klimaforandringerne intensiveres globalt og fører til stigende temperaturer. Arktis, som er et sårbart og ekstremt miljø, står over for en forstærket opvarmningseffekt, kaldet den arktiske forstærkning. I dette hurtigt skiftende miljø lagres store mængder kulstof (1,460 – 1,600 Pg C) i permafrosten. Det er fire gange mere end den mængde kulstof, som mennesker har udledt i moderne tid. Stigende temperaturer ændrer de skrøbelige arktiske økosystemer, hvilket fører til optøning af permafrosten og ændringer i vegetationen. Det påvirker den lokale kulstofudledningsdynamik og forstærke klimaforandringerne yderligere.
For at vurdere fremtidige drivhusgassemissioner i højarktiske omgivelser blev den dynamiske globale vegetationsmodel LPJ-GUESS anvendt til at simulere udledningen af drivhusgasser. For at reducere usikkerheden i fremtidige klimasimuleringer blev der brugt tre forskellige klimamodeller under to forskellige fælles socioøkonomiske veje (SSP1-2.6 og SSP5-8.5). Undersøgelsen blev udført med to forskellige indstillinger, et tørt og et vådt økosystem i et højarktisk område. Det tørre økosystem blev sammenlignet med en kassiop-hede, og det våde med en mose på Zackenberg forskningsstation i Nordøstgrønland. Modellen undervurderer CO2- og CH4-fluxene betydeligt sammenlignet med observationer. Udledningen af kuldioxid er undervurderet på grund af fraværet af planter. Undervurderede metanemissioner skyldes sandsynligvis manglen på simulering af jordopvarmningsprocesser. Derudover resulterer for få simulerede planter i et begrænset input af strøelse og dermed mindre kulstof til rådighed i jorden til metanproduktion. Forskellige versioner af modellen LPJ-GUESS kan forbedre modelleringsevnen. Desuden foreslås det, at vegetationens og jordens egenskaber og dynamik tilpasses til det veltilpassede højarktiske miljø. Tilpasning af simuleringsforsøget er meget vigtigt for at kunne simulere fremtidige drivhusgasemissioner nøjagtigt og give estimater af drivhusgasdynamikken i dette kulstofrige miljø. (Less)
Popular Abstract
Climate change-driven warming is intensifying globally and is further amplified in the Arctic. Arctic soils contain vast amounts of carbon locked in frozen soils. This carbon is likely to be unlocked by warming and immensely contribute to future carbon emissions, further fueling global warming.
To predict future emissions and linked temperature increases, it is crucial to accurately model High-Arctic ecosystems with their enormous carbon storage. To assess those emissions, the computer model LPJ-GUESS—a tool simulating plants, soils and greenhouse gas emissions—was used to simulate past and future carbon dioxide and methane emissions. Advanced modelling tools like LPJ-GUESS contribute to closing both the spatial and temporal knowledge... (More)
Climate change-driven warming is intensifying globally and is further amplified in the Arctic. Arctic soils contain vast amounts of carbon locked in frozen soils. This carbon is likely to be unlocked by warming and immensely contribute to future carbon emissions, further fueling global warming.
To predict future emissions and linked temperature increases, it is crucial to accurately model High-Arctic ecosystems with their enormous carbon storage. To assess those emissions, the computer model LPJ-GUESS—a tool simulating plants, soils and greenhouse gas emissions—was used to simulate past and future carbon dioxide and methane emissions. Advanced modelling tools like LPJ-GUESS contribute to closing both the spatial and temporal knowledge gap in High-Arctic carbon emissions.
However, the model showed limitations in capturing the reality of this harsh environment. It underestimated the carbon exchange in the High-Arctic because of too cold soil temperatures and too few plants compared to what can be observed in nature. Both of which are critical drivers for carbon emissions.
To better simulate High-Arctic carbon emissions, processes in the model LPJ-GUESS must be adapted to the unique High-Arctic conditions. Adapting the temperature dependent plant parameters or processes and traits of the soil could immensely improve predictions.
Understanding High-Arctic carbon emissions is inevitable in order to make realistic predictions for future greenhouse gas concentrations. The insights can help us make the right decisions for society. After all, if the Arctic melts, it will affect us all. (Less)
Please use this url to cite or link to this publication:
author
Christiansen, Lasse LU
supervisor
organization
alternative title
Modelling future High-Arctic carbon emissions
course
NGEM01 20251
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Physical Geography and Ecosystem Analysis, High-Arctic, carbon flux measurements, methane, carbon dioxide, wet ecosystem, dry ecosystem, Zackenberg valley, climate change, LPJ-GUESS, ecosystem modeling
publication/series
Student thesis series INES
report number
731
language
English
id
9210125
date added to LUP
2025-08-19 09:00:25
date last changed
2025-08-19 09:00:25
@misc{9210125,
  abstract     = {{Climate change is intensifying globally, leading to rising temperatures. The Arctic being a vulnerable and extreme environment faces an enhanced warming effect, referred to as the Arctic amplification. In this rapidly changing environment, high amounts of carbon (1,460 – 1,600 Pg C) are stored in permafrost. This is four times the amount of carbon being emitted by humans in modern times. Increasing temperatures are changing fragile Arctic ecosystems, leading to permafrost thaw and change of vegetation. This will affect local carbon emission dynamics further enhancing climate change.
To assess future greenhouse gas emissions in a High-Arctic setting, the dynamic global vegetation model LPJ-GUESS was used to simulate GHG emissions. To reduce uncertainty in future climate simulations, three different climate models were used under two different shared socio-economic pathways (SSP1-2.6 and SSP5-8.5). The study was conducted with two different settings, a dry and wet ecosystem in a High Arctic location. The dry ecosystem was compared to a cassiope heath, and the wet to a fen at the Zackenberg research station in Northeast Greenland. The model significantly underestimates CO2 and CH4 fluxes compared to observations. Carbon dioxide emissions are underestimated due to plant absence. Underestimated methane emissions are likely caused by the lack of simulating soil warming processes. In addition, too few simulated plants result in limited litter input and therefore less carbon available in the soil for methane production. Different versions of the model LPJ-GUESS might improve modeling performance. In addition, vegetation and soil properties and dynamics are suggested to be adapted to the well adapted High Arctic environment. Adapting the simulation attempt is highly important in order to simulate future greenhouse gas emissions accurately and give estimates of greenhouse gas dynamics of this carbon rich environment.}},
  author       = {{Christiansen, Lasse}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Student thesis series INES}},
  title        = {{Modeling long-term carbon dynamics for High Arctic dry and wet ecosystems}},
  year         = {{2025}},
}