Abstract
Modelling simulations of palaeoclimate and past vegetation form and function can contribute to global change research by constraining predictions of potential earth system responses to future warming, and by providing useful insights into the ecophysiological tolerances and threshold responses of plants to varying degrees of atmospheric change. We contrasted HadCM3LC simulations of Amazonian forest at the last glacial maximum (LGM; 21 kyr ago) and a Younger Dryas-like period (13-12 kyr ago) with predicted responses of future warming to provide estimates of the climatic limits under which the Amazon forest remains relatively stable. Our simulations indicate that despite lower atmospheric CO2 concentrations and increased aridity during the LGM, Amazonia remains mostly forested, and that the cooling climate of the Younger Dryas-like period in fact causes a trend toward increased above-ground carbon balance relative to today. The vegetation feedbacks responsible for maintaining forest integrity in past climates (i.e. decreased evapotranspiration and reduced plant respiration) cannot be maintained into the future. Although elevated atmospheric CO2 contributes to a positive enhancement of plant carbon and water balance, decreased stomatal conductance and increased plant and soil respiration cause a positive feedback that amplifies localized drying and climate warming. We speculate that the Amazonian forest is currently near its critical resiliency threshold, and that even minor climate warming may be sufficient to promote deleterious feedbacks on forest integrity.
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- Baker P. A., Rigsby C. A., Seltzer G. O., Fritz S. C., Lowenstein T. K., Bacher N. P., Veliz C. Tropical climate changes at millennial and orbital timescales on the Bolivian Altiplano. Nature. 2001 Feb 8;409(6821):698–701. doi: 10.1038/35055524. [DOI] [PubMed] [Google Scholar]
- Baker P. A., Seltzer G. O., Fritz S. C., Dunbar R. B., Grove M. J., Tapia P. M., Cross S. L., Rowe H. D., Broda J. P. The history of South American tropical precipitation for the past 25,000 years. Science. 2001 Jan 26;291(5504):640–643. doi: 10.1126/science.291.5504.640. [DOI] [PubMed] [Google Scholar]
- Cox P. M., Betts R. A., Jones C. D., Spall S. A., Totterdell I. J. Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature. 2000 Nov 9;408(6809):184–187. doi: 10.1038/35041539. [DOI] [PubMed] [Google Scholar]
- Guilderson T. P., Fairbanks R. G., Rubenstone J. L. Tropical temperature variations since 20,000 years ago: modulating interhemispheric climate change. Science. 1994 Feb 4;263(5147):663–665. doi: 10.1126/science.263.5147.663. [DOI] [PubMed] [Google Scholar]
- Haffer J. Speciation in amazonian forest birds. Science. 1969 Jul 11;165(3889):131–137. doi: 10.1126/science.165.3889.131. [DOI] [PubMed] [Google Scholar]
- Haug G. H., Hughen K. A., Sigman D. M., Peterson L. C., Röhl U. Southward migration of the intertropical convergence zone through the Holocene. Science. 2001 Aug 17;293(5533):1304–1308. doi: 10.1126/science.1059725. [DOI] [PubMed] [Google Scholar]
- Hughen K. A., Southon J. R., Lehman S. J., Overpeck J. T. Synchronous radiocarbon and climate shifts during the last deglaciation. Science. 2000 Dec 8;290(5498):1951–1955. doi: 10.1126/science.290.5498.1951. [DOI] [PubMed] [Google Scholar]
- Körner Christian. Through enhanced tree dynamics carbon dioxide enrichment may cause tropical forests to lose carbon. Philos Trans R Soc Lond B Biol Sci. 2004 Mar 29;359(1443):493–498. doi: 10.1098/rstb.2003.1429. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laurance W. F., Cochrane M. A., Bergen S., Fearnside P. M., Delamônica P., Barber C., D'Angelo S., Fernandes T. Environment. The future of the Brazilian Amazon. Science. 2001 Jan 19;291(5503):438–439. doi: 10.1126/science.291.5503.438. [DOI] [PubMed] [Google Scholar]
- Malhi Y, Grace J. Tropical forests and atmospheric carbon dioxide. Trends Ecol Evol. 2000 Aug;15(8):332–337. doi: 10.1016/s0169-5347(00)01906-6. [DOI] [PubMed] [Google Scholar]
- Malhi Yadvinder. Carbon in the atmosphere and terrestrial biosphere in the 21st century. Philos Trans A Math Phys Eng Sci. 2002 Dec 15;360(1801):2925–2945. doi: 10.1098/rsta.2002.1098. [DOI] [PubMed] [Google Scholar]
- Maslin M. A., Burns S. J. Reconstruction of the Amazon Basin effective moisture availability over the past 14,000 years. Science. 2000 Dec 22;290(5500):2285–2287. doi: 10.1126/science.290.5500.2285. [DOI] [PubMed] [Google Scholar]
- Mayle F. E., Burbridge R., Killeen T. J. Millennial-scale dynamics of southern Amazonian rain forests. Science. 2000 Dec 22;290(5500):2291–2294. doi: 10.1126/science.290.5500.2291. [DOI] [PubMed] [Google Scholar]
- Mayle Francis E., Beerling David J., Gosling William D., Bush Mark B. Responses of Amazonian ecosystems to climatic and atmospheric carbon dioxide changes since the last glacial maximum. Philos Trans R Soc Lond B Biol Sci. 2004 Mar 29;359(1443):499–514. doi: 10.1098/rstb.2003.1434. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pielke Roger A., Sr, Marland Gregg, Betts Richard A., Chase Thomas N., Eastman Joseph L., Niles John O., Niyogi Dev Dutta S., Running Steven W. The influence of land-use change and landscape dynamics on the climate system: relevance to climate-change policy beyond the radiative effect of greenhouse gases. Philos Trans A Math Phys Eng Sci. 2002 Aug 15;360(1797):1705–1719. doi: 10.1098/rsta.2002.1027. [DOI] [PubMed] [Google Scholar]
- Stute M., Forster M., Frischkorn H., Serejo A., Clark J. F., Schlosser P., Broecker W. S., Bonani G. Cooling of Tropical Brazil (5{degrees}C) During the Last Glacial Maximum. Science. 1995 Jul 21;269(5222):379–383. doi: 10.1126/science.269.5222.379. [DOI] [PubMed] [Google Scholar]
- Thompson L. G., Mosley-Thompson E., Davis M. E., Lin P. N., Henderson K. A., Cole-Dai J., Bolzan J. F., Liu K. B. Late glacial stage and holocene tropical ice core records from huascaran, peru. Science. 1995 Jul 7;269(5220):46–50. doi: 10.1126/science.269.5220.46. [DOI] [PubMed] [Google Scholar]
- Thompson LG, Davis ME, Mosley-Thompson E, Sowers TA, Henderson KA, Zagorodnov VS, Lin P, Mikhalenko VN, Campen RK, Bolzan JF. A 25,000-year tropical climate history from bolivian ice cores . Science. 1998 Dec 4;282(5395):1858–1864. doi: 10.1126/science.282.5395.1858. [DOI] [PubMed] [Google Scholar]