热带增宽及其对中国东部亚热带森林植被的影响

全球气候变暖已是不争的事实，现今气候变暖的趋势已由每百年（1901--2000）增加0．6℃的记录升高为0．74℃（1906—2005）。其中高纬度地区增温特别显著，成为世界关注的热点。与之对比，热带地区的气候变化以及热带森林对它的反应报道甚少。事实上，自1970s中期以来，热带温度是每lO年升高0．26oC；同时气候模型预测到本世纪末热带地区温度将上升2．1-4．5℃。这些预测是有根据的，但究竟不是直接的证据。因此，本文综合了许多专家对热带地球物理学和大气层特性的多年观测、分析和研究的成果，其结论认为：至少自1979年以来许多热带大气层固有的特征发生变化并向地球极地推进和位移，这些根据是：（1）热带高空的哈德利环流增强并向极地扩展；（21位于热带边缘的亚热带射流向极地移动；（3）热带亚热带对流层顶高度和位置的变化；（4）热带高空平流层臭氧柱总量浓度的变化。据上述特征的变化证明数十年来热带向极地增宽纬度2°～5°（～8°），一般确认为2．5°。由于热带增宽的驱动，广东50年的气温记录表明气候持续变暖，按增暖趋势推算，预估到2020年，现在的雷州半岛南部可能变成中热带；广东东南沿海将由目前的南亚热带变为北热带（占全省面积约1／3）；其余大部分地区为南亚热带；中亚热带基本上将退出广东（仅剩下东北角一偶）。此预测意味着南岭地区将成为南亚热带的边缘地。

Tropical belt widening and its impact on China eastern subtopic forest vegetation

Globa warming was an imdisputable fact that Over the last 100 years (1906-2005), there has been a 0.74 ℃ increase in global surface temperatures, which is larger than the 0.6℃ increase for the period from 1901-2000. In whole world, the impact of global warming is particularly significant in high latitude regions and has become the focus of research worldwide. By contrast, cli-mate changes in tropical areas and the consequences associated with it has received far less attention. In fact, Tropical temperatures have increased by 0.26℃ per decade since the mid 1970s, and climate models predict that the temperatures in tropical forest re-gions will rise 2.1～4.5 ℃ by the end of this century, and some climate models predict that the temperatures in tropical forest regions will rise 2.1～4.5 ℃ by the end of this century. This, however, is a prediction, not direct evidence. This article provides a summary of extensive studies and observations on geophysics and tropical atmosphere. The results of the studies indicate that many inherent characteristics of tropical atmosphere have changed and a significant poleward expansion has been detected since 1979. The evidence includes: (1) Hadley circulation has been lbund more active and extended poleward; (2) the subtropical jetstream on the edge of tropics move to poleward; (3) The changes in the height and position of tropical and subtropical Tropopause has been detected; (4) The change of total column ozone concentration in stratosphere has been detected. Basis on the change of those atmosphere charecteristics, the results of which can prove that the tropical belt has moved poleward 2.5°[from2° to 5°(～8°)]. Because of tropical belt widening, the climate continues to warm in Guangdong province according to the climate record over last 50 years, based on the tendency of warm in this area, a climate estimate of 2020 year was put forwarded, it is estimated that by 2020 south Leizhou Peninsula (currently located on the northern fringe of the tropical area in Guangdong province) would be in mid-tropic, the southeast coast of Guangdung (～1/3 land of Guangdong) would be moving from south subtropical zone into north tropic zone, and the mid-subtropical area would be basically disappeared from Guangdong. This forecast implies that Nanling mountains area would be the margin of the south subtropics.