A sea of change: Monitoring the ocean's carbon cycle

D. M. Karl and C. D. Winn

Department of Oceanography, University of Hawaii, Honolulu, Hawaii 96822, USA

Introduction

The Earth undergoes major processes of change that are reckoned in scales of decades to millennia. Most of these changes result from natural causes. During the past century, however, human activities have contributed directly to what is now considered an inevitable, detrimental change in the global environment. Although the proximate cause of this change appears to be the atmospheric accumulation of so-called "greenhouse" gases (CO₂, H₂O, NO₂, CH₄, chlorofluorcarbons) as a direct consequence of urbanization and industrialization, the ultimate cause clearly is overpopulation of our planet.