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Margareta Johansson

Researcher

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Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system

Author

  • Terry V. Callaghan
  • Lars Olof Björn
  • Yuri Chernov
  • Terry Chapin
  • Torben Christensen
  • Brian Huntley
  • Rolf A. Ims
  • Margareta Johansson
  • Dyanna Jolly
  • Sven Jonasson
  • Nadya Matveyeva
  • Nicolai Panikov
  • Walter Oechel
  • Gus Shaver
  • Sibyll Schaphoff
  • Stephen Sitch
Show all

Summary, in English

Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net effects of climate change on terrestrial feedbacks to the climate system. This uncertainty applies to magnitude, and even direction of some of the feedbacks.

Department/s

  • Molecular Cell Biology
  • Dept of Physical Geography and Ecosystem Science

Publishing year

2004

Language

English

Pages

459-468

Publication/Series

Ambio: a Journal of Human Environment

Volume

33

Issue

7

Document type

Journal article review

Publisher

Springer

Topic

  • Physical Geography
  • Biological Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 0044-7447