Projecting future climate change: Implications of carbon cycle model intercomparisons

Abstract The behavior of the terrestrial carbon cycle under historical and future climate change is examined using the University of Victoria Earth System Climate Model, now coupled to a dynamic terrestrial vegetation and global carbon cycle model. When forced by historical emissions of CO2 from fossil fuels and land-use change, the coupled climate–carbon cycle model accurately reproduces historical atmospheric CO2 trends, as well as terrestrial and oceanic uptake for the past two decades. Under six twenty-first-century CO2 emissions scenarios, both terrestrial and oceanic carbon sinks continue to increase, though terrestrial uptake slows in the latter half of the century. Climate–carbon cycle feedbacks are isolated by comparing a coupled model run with a run where climate and the carbon cycle are uncoupled. The modeled positive feedback between the carbon cycle and climate is found to be relatively small, resulting in an increase in simulated CO2 of 60 ppmv at the year 2100. Including non-CO2 greenhouse gas forcing and increasing the model’s climate sensitivity increase the effect of this feedback to 140 ppmv. The UVic model does not, however, simulate a switch from a terrestrial carbon sink to a source during the twenty-first century, as earlier studies have suggested. This can be explained by a lack of substantial reductions in simulated vegetation productivity due to climate changes.

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The African contribution to the global climate-carbon cycle feedback of the 21st century

Biogeosciences Discussions ◽

10.5194/bgd-5-4847-2008 ◽

2008 ◽

Vol 5 (6) ◽

pp. 4847-4866 ◽

Cited By ~ 6

Author(s):

P. Friedlingstein ◽

P. Cadule ◽

S. L. Piao ◽

P. Ciais ◽

S. Sitch

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

21St Century ◽

Climate Model ◽

Global Climate ◽

Future Climate ◽

Future Climate Change ◽

Amazon Forest ◽

Terrestrial Carbon ◽

Carbon Cycle Model

Abstract. Future climate change will have impact on global and regional terrestrial carbon balances. The fate of African tropical forests over the 21st century has been investigated through global coupled climate carbon cycle model simulations. Under the SRES-A2 socio-economic CO2 emission scenario of the IPCC, and using the Institut Pierre Simon Laplace coupled ocean-terrestrial carbon cycle and climate model, IPSL-CM4-LOOP, we found that the warming over African ecosystems induces a reduction of net ecosystem productivity, making a 20% contribution to the global climate-carbon cycle positive feedback. However, the African rainforest ecosystem alone makes only a negligible contribution to the overall feedback, much smaller than the one arising from the Amazon forest. This is first because of the two times smaller area of forest in Africa, but also because of the relatively lower local land carbon cycle sensitivity to climate change. This beneficial role of African forests in mitigating future climate change should be taken into account when designing forest conservation policy.

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Role of volcanic forcing on future global carbon cycle

Earth System Dynamics Discussions ◽

10.5194/esdd-2-133-2011 ◽

2011 ◽

Vol 2 (1) ◽

pp. 133-159

Author(s):

J. F. Tjiputra ◽

O. H. Otterå

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

21St Century ◽

Volcanic Eruptions ◽

Future Climate Change ◽

Small Scale ◽

Carbon Uptake ◽

Carbon Cycle Model ◽

Large Volcanic Eruptions

Abstract. Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller but more frequent eruptions, such as Pinatubo, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before return to the warming trend. Therefore, the climate change is approximately delayed by several decades and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45% increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by reduced CO2 partial pressure gradient between ocean and atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even in the relatively extreme scenario where large volcanic eruptions occur every five-years period, the induced cooling only leads to a reduction of 46 ppmv atmospheric CO2 concentration as compared to the reference projection of 878 ppmv, at the end of the 21st century. With respect to sulphur injection geoengineering method, our study suggest that small scale but frequent mitigation is more efficient than the opposite. Moreover, the longer we delay, the more difficult it would be to counteract climate change.

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Global response of the terrestrial biosphere to CO2and climate change using a coupled climate-carbon cycle model

Global Biogeochemical Cycles ◽

10.1029/2001gb001827 ◽

2002 ◽

Vol 16 (4) ◽

pp. 31-1-31-15 ◽

Cited By ~ 23

Author(s):

M. Berthelot ◽

P. Friedlingstein ◽

P. Ciais ◽

P. Monfray ◽

J. L. Dufresne ◽

...

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

Cycle Model ◽

Terrestrial Biosphere ◽

Global Response ◽

Carbon Cycle Model

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Atmospheric carbon dioxide and climate change since the Late Jurassic (150Ma) derived from a global carbon cycle model

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2016.04.002 ◽

2016 ◽

Vol 454 ◽

pp. 82-90 ◽

Cited By ~ 6

Author(s):

Hirohiko Kashiwagi

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Carbon Cycle ◽

Atmospheric Carbon Dioxide ◽

Late Jurassic ◽

Global Carbon Cycle ◽

Cycle Model ◽

Carbon Cycle Model ◽

Atmospheric Carbon ◽

Global Carbon

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Climate–Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison

Journal of Climate ◽

10.1175/jcli3800.1 ◽

2006 ◽

Vol 19 (14) ◽

pp. 3337-3353 ◽

Cited By ~ 2085

Author(s):

P. Friedlingstein ◽

P. Cox ◽

R. Betts ◽

L. Bopp ◽

W. von Bloh ◽

...

Keyword(s):

Climate Change ◽

Carbon Cycle ◽

Net Primary Productivity ◽

Future Climate ◽

Climate Feedback ◽

Future Climate Change ◽

Ocean Carbon Cycle ◽

Intergovernmental Panel ◽

Ocean Carbon ◽

The Impact

Abstract Eleven coupled climate–carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. The models were forced by historical emissions and the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A2 anthropogenic emissions of CO2 for the 1850–2100 time period. For each model, two simulations were performed in order to isolate the impact of climate change on the land and ocean carbon cycle, and therefore the climate feedback on the atmospheric CO2 concentration growth rate. There was unanimous agreement among the models that future climate change will reduce the efficiency of the earth system to absorb the anthropogenic carbon perturbation. A larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5°C. All models simulated a negative sensitivity for both the land and the ocean carbon cycle to future climate. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. Also, a majority of the models located the reduction of land carbon uptake in the Tropics. However, the attribution of the land sensitivity to changes in net primary productivity versus changes in respiration is still subject to debate; no consensus emerged among the models.

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