Hsieh Chih-hao, Glaser Sarah M, Lucas Andrew J, Sugihara George
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0202, USA.
Nature. 2005 May 19;435(7040):336-40. doi: 10.1038/nature03553.
The prospect of rapid dynamic changes in the environment is a pressing concern that has profound management and public policy implications. Worries over sudden climate change and irreversible changes in ecosystems are rooted in the potential that nonlinear systems have for complex and 'pathological' behaviours. Nonlinear behaviours have been shown in model systems and in some natural systems, but their occurrence in large-scale marine environments remains controversial. Here we show that time series observations of key physical variables for the North Pacific Ocean that seem to show these behaviours are not deterministically nonlinear, and are best described as linear stochastic. In contrast, we find that time series for biological variables having similar properties exhibit a low-dimensional nonlinear signature. To our knowledge, this is the first direct test for nonlinearity in large-scale physical and biological data for the marine environment. These results address a continuing debate over the origin of rapid shifts in certain key marine observations as coming from essentially stochastic processes or from dominant nonlinear mechanisms. Our measurements suggest that large-scale marine ecosystems are dynamically nonlinear, and as such have the capacity for dramatic change in response to stochastic fluctuations in basin-scale physical states.
环境的快速动态变化前景是一个紧迫问题，具有深远的管理和公共政策影响。对突然的气候变化和生态系统不可逆转变化的担忧，源于非线性系统具有产生复杂和“病态”行为的可能性。非线性行为已在模型系统和一些自然系统中得到证实，但其在大规模海洋环境中的出现仍存在争议。在此，我们表明，北太平洋关键物理变量的时间序列观测结果看似显示出这些行为，但并非确定性非线性，最好描述为线性随机。相比之下，我们发现具有类似性质的生物变量时间序列呈现出低维非线性特征。据我们所知，这是对海洋环境大规模物理和生物数据非线性的首次直接检验。这些结果解决了关于某些关键海洋观测中快速变化起源的持续争论，即这些变化本质上是来自随机过程还是占主导地位的非线性机制。我们的测量表明，大规模海洋生态系统是动态非线性的，因此有能力因盆地尺度物理状态的随机波动而发生巨大变化。
