I modsætning til hvad IPCC tidligere har påstået var "settled science" viser det sig, at netto optaget af Co2 er højere end det, der udløses ved optøning og afsmeltning.
Opposite to expectations," as the 42 researchers note, their results revealed the existence of "a small negative carbon cycle feedback from past changes in the long-term accumulation rates of northern peatlands." More specifically, they state that "total carbon accumulated over the last 1000 years is linearly related to contemporary growing season length and photosynthetically active radiation, suggesting that variability in net primary productivity is more important than decomposition in determining long-term carbon accumulation."
Reference
Charman, D.J., Beilman, D.W., Blaauw, M., Booth, R.K., Brewer, S., Chambers, F.M., Christen, J.A., Gallego-Sala, A., Harrison, S.P., Hughes, P.D.M., Jackson, S.T., Korhola, A., Mauquoy, D., Mitchell, F.J.G., Prentice, I.C., van der Linden, M., De Vleeschouwer, F., Yu, Z.C., Alm, J., Bauer, I.E., Corish, Y.M.C., Garneau, M., Hohl, V., Huang, Y., Karofeld, E., Le Roux, G., Loisel, J., Moschen, R., Nichols, J.E., Nieminen, T.M., MacDonald, G.M., Phadtare, N.R., Rausch, N., Sillasoo, U., Swindles, G.T., Tuoittila, E.-S., Ukonmaanaho, L., Valiranta, M., van Bellen, S., van Geel, B., Vitt, D.H. and Zhao, Y. 2013. Climate-related changes in peatland carbon accumulation during the last millennium. Biogeosciences 10: 929-944.
In introducing their enlightening Biogeosciences paper on the subject, Charman et al. (2013) write that "it is generally assumed that higher temperatures will increase peat decay, causing a positive feedback to climate warming." But feeling uneasy about this assumption, they were compelled to study it in more detail by employing "a new extensive database of peat profiles across northern high latitudes to examine spatial and temporal patterns of carbon accumulation over the past millennium." And what did they find by so doing?
"Opposite to expectations," as the 42 researchers note, their results revealed the existence of "a small negative carbon cycle feedback from past changes in the long-term accumulation rates of northern peatlands." More specifically, they state that "total carbon accumulated over the last 1000 years is linearly related to contemporary growing season length and photosynthetically active radiation, suggesting that variability in net primary productivity is more important than decomposition in determining long-term carbon accumulation."
Furthermore, as Charman et al. continue, "northern peatland carbon sequestration rate declined over the climate transition from the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA), probably because of lower LIA temperatures combined with increased cloudiness suppressing net productivity," which finding suggests that carbon accumulation in northern peatlands would likely increase in response to any future climate warming. Therefore, as they conclude in the final sentence of their paper, the 42 researchers state that "based on our analyses of carbon accumulation over the past millennium, and contrary to the conclusions from soil decay models (Ise et al., 2008; Dorrepaal et al., 2009), we suggest that carbon sequestration may increase in many high-latitude peatlands in response to future climate warming over the next century."
Additional References
Dorrepaal, E., Toet, S., van Logtestijn, R.S.P., Swart, E., van de Weg, M.J., Callaghan, T.V. and Aerts, R. 2009. Carbon respiration from subsurface peat accelerated by climate warming in the sub-arctic. Nature 460: 616-619.
Ise, T., Dunn, A.L., Wofsy, S.C. and Moorcroft, P.R. 2008. High sensitivity of peat decomposition to climate change through water-table feedback.Nature Geoscience 1: 763-766.
