Late Quaternary geomagnetic field dynamics and abrupt changes

地磁场在上个世纪发生了巨大的变化。北磁极（NMP）位置的变化和偶极子场（即地球磁场的主要组成部分）的快速下降最能说明这一点。 NMP 在历史上仅限于加拿大北极地区，最近已进入北冰洋。直接观测表明，自 1970 年代初以来，NMP 的迁移急剧增加，从每年 9 公里增加到每年 41 公里，并在 2003 年增加到每年近 60 公里，而在过去 50 年里，坚毅湾地磁观测站测量的强度年变化率从约 10 nT/年增加到近 70 nT/年。这些惊人的变化导致了以下问题的提出：“我们是否处于大规模地磁变化的初始阶段，甚至是逆转？”，如果是的话，“大规模地磁变化的原因（在地球核心）和后果（对地球环境）是什么？”要回答这些基本问题，必须首先将历史记录置于更长期的地质背景中。因此，该研究计划的长期目标是确定晚第四纪地磁场的高频动态，特别强调突变及其对气候可能的影响。该研究计划将首次对北极地磁场动力学进行大规模研究。此外，通过选择沉积物积累率非常高的取芯地点，拟议的研究将以刚刚开始探索的时间分辨率（百年到千年的时间尺度）研究地磁场变化。这些观测结果将：1）能够测试根据历史地磁记录提出的假设，2）为地球发电机建模提供宝贵的数据，3）将当前 NMP 的剧烈塌陷和迁移置于详细的地质背景中。最后，在气候快速变化的时期，探索气候变化与地磁场形态之间的潜在联系值得特别关注，因为目前的数值气候模型还没有考虑宇宙射线或地磁场对气候的可能影响。

The geomagnetic field has undergone dramatic changes over the last century. This is best illustrated by changes in the position of the North Magnetic Pole (NMP) and the rapid decline of the dipole field (i.e, the main component of Earth's magnetic field). The NMP, restricted to the Canadian Arctic during historical times, has recently moved into the Arctic Ocean. Direct observations reveal that the migration of the NMP has increased dramatically since the early 1970's from 9 km/yr to 41 km/yr and to almost 60 km/yr in 2003, whereas the annual rate of change in intensity measured at the Resolute Bay geomagnetic observatory has increased from about 10 nT/yr to almost 70 nT/yr over the last 50 years. These spectacular changes lead to the formulation of the following questions: "Are we in the initial stages of a large-scale geomagnetic change, or even a reversal?", and if so, "What are the causes (in Earth's core) and consequences (to Earth's environment) of a large scale geomagnetic change?" To answer these fundamental questions,the historical record must first be placed into a longer geological context. The long-term goal of this research program is thus to determine the high frequency dynamics of the geomagnetic field during the Late Quaternary with a special emphasis on abrupt changes and their possible influence on climate. This research program will provide the first large-scale study of geomagnetic field dynamics in the Arctic. In addition, by selecting coring sites with very high sediment accumulation rates, the proposed research will investigate geomagnetic field variability at a temporal resolution that is just beginning to be explored, the centennial to millennial timescales. These observations will: 1) enable testing of hypotheses developed from the historical geomagnetic record, 2) yield invaluable data for geodynamo modelling, and 3) place the current dramatic collapse and migration of the NMP into a detailed geological context. Finally, exploring the potential linkages between climate change and geomagnetic field morphology deserves special attention at this time of rapid climatic change as no current numerical climate model accounts for the possible influence of cosmic rays or the geomagnetic field on climate.