According to temperature reconstruction made within an [[Old Earth]] paradigm, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). Some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere. However, many scientists also think that human activities were most likely the cause of the the planet's recent warming. | According to temperature reconstruction made within an [[Old Earth]] paradigm, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). Some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere. However, many scientists also think that human activities were most likely the cause of the the planet's recent warming. |