给定一篇文章和一个主题，生成一个总结来概括该主题在文章中的重点。


主题：气候变化
文章：The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.
The current warming trend is of particular significance because most of it is extremely likely (greater than 95 percent probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia.
气候变化的文章指出地球的气候已经在历史上发生过多次变化，大部分变化是由地球轨道微小变化所引起的。然而，当前的全球变暖趋势与以往不同，这是由于自20世纪中叶以来人类活动的影响，导致变暖速度过快。这是具有重大意义的。