What the proxy records make abundantly clear is that there have been significant naturalchanges in the climate over timescales longer than a few thousand years.
代理记录充分表明的是，气候在比几千年更长的时间跨度内发生了重大的自然变化。
2
They studied the sun's movement and also paid attention to other naturalchanges such as air temperature, water and plant growth.
他们研究了太阳的运动，还关注了其他自然变化，如气温、水和植物生长。
3
We think it quite probably derives from naturalchanges in the voyage.