Influence of Climate Variability and Change
on the Structure, Dynamics and
Exploitation of Marine Ecosystems
MANUEL BARANG E
1 Introduction: The Global Ocean’s Response to Climate
Variability and Change
Global warming has been the subject of considerable debate in recent years.
Present estimates indicate that the Earth’s surface temperature has increased at a
rate of 0.1 °C per decade over the 20th century (Figure 1). Although some of this
warming may be caused by natural variability there is now consistent evidence of
an anthropogenic signal in the climate record for at least the last 50 years, but
possibly over the last 100 years. Such a signal should be expected. In the last
century the world’s population has increased by a factor of four, and industrial
output has increased 40 times. Human action has transformed nearly 50% of the
land surface, and the burning of fossil fuels has increased the atmospheric
concentration of carbon dioxide (CO
) to levels not exceeded in at least 420 000
years. These are some of the environmental costs for the planet of improving the
standards of living, education and leisure of about a quarter of the world’s
population. Can we achieve equal successes for the other 75% of the world’s
population without destroying our support systems? Based on IPCC scenarios of
future emissions, temperature increases of between 1.4 and 5.8 °C between 1990
and 2100 are expected. A further 1% annual increase in CO
will double the
current CO
levels in the atmosphere in 70 years, and quadruple them in 140
years. What can we expect from these changes? We know that the Earth does not
respond to global changes uniformly, and that the complexity of its response
sometimes defies purely mechanical analysis (Table 1). Its vital organs, switches
and choke points respond to global changes in non-linear, asynchronous ways,
resulting in positive as well as negative feedbacks. The mechanisms at play have
57
M. E. Mann, R. S. Bradley and M. K. Hughes, Geophys. Res. Lett., 1999, 26, 759—762.
IPCC, Third assessment Report of working group 1. Summary for policymakers, 2001.
J. R. McNeill, Something New Under the Sun: An Environmental History of the Twentieth-Century
World, Allen Lane/W. W. Norton, 2000.
J. R. Petit, J. Jouzel, D. Raynaud, N. I. Barkov, J.-M. Barnola, I. Basile, M. Bender, J. Chappellaz,
M. Davis, G. Delaygue, M. Delmotte, V. M. Kotlyakov, M. Legrand, V. Y. Lipenkov, C. Lorius, L.
Pepin, C. Ritz, E. Saltzmank and M. Stievenard, Nature, 1999, 399, 429—436.
S. Manabe and R. J. Stouffer, Nature, 1993, 364, 215—218.
Issues in Environmental Science and Technology, No. 17
Global Environmental Change
© The Royal Society of Chemistry, 2002
on the Structure, Dynamics and
Exploitation of Marine Ecosystems
MANUEL BARANG E
1 Introduction: The Global Ocean’s Response to Climate
Variability and Change
Global warming has been the subject of considerable debate in recent years.
Present estimates indicate that the Earth’s surface temperature has increased at a
rate of 0.1 °C per decade over the 20th century (Figure 1). Although some of this
warming may be caused by natural variability there is now consistent evidence of
an anthropogenic signal in the climate record for at least the last 50 years, but
possibly over the last 100 years. Such a signal should be expected. In the last
century the world’s population has increased by a factor of four, and industrial
output has increased 40 times. Human action has transformed nearly 50% of the
land surface, and the burning of fossil fuels has increased the atmospheric
concentration of carbon dioxide (CO
) to levels not exceeded in at least 420 000
years. These are some of the environmental costs for the planet of improving the
standards of living, education and leisure of about a quarter of the world’s
population. Can we achieve equal successes for the other 75% of the world’s
population without destroying our support systems? Based on IPCC scenarios of
future emissions, temperature increases of between 1.4 and 5.8 °C between 1990
and 2100 are expected. A further 1% annual increase in CO
will double the
current CO
levels in the atmosphere in 70 years, and quadruple them in 140
years. What can we expect from these changes? We know that the Earth does not
respond to global changes uniformly, and that the complexity of its response
sometimes defies purely mechanical analysis (Table 1). Its vital organs, switches
and choke points respond to global changes in non-linear, asynchronous ways,
resulting in positive as well as negative feedbacks. The mechanisms at play have
57
M. E. Mann, R. S. Bradley and M. K. Hughes, Geophys. Res. Lett., 1999, 26, 759—762.
IPCC, Third assessment Report of working group 1. Summary for policymakers, 2001.
J. R. McNeill, Something New Under the Sun: An Environmental History of the Twentieth-Century
World, Allen Lane/W. W. Norton, 2000.
J. R. Petit, J. Jouzel, D. Raynaud, N. I. Barkov, J.-M. Barnola, I. Basile, M. Bender, J. Chappellaz,
M. Davis, G. Delaygue, M. Delmotte, V. M. Kotlyakov, M. Legrand, V. Y. Lipenkov, C. Lorius, L.
Pepin, C. Ritz, E. Saltzmank and M. Stievenard, Nature, 1999, 399, 429—436.
S. Manabe and R. J. Stouffer, Nature, 1993, 364, 215—218.
Issues in Environmental Science and Technology, No. 17
Global Environmental Change
© The Royal Society of Chemistry, 2002