Complex sentence: Lockwood 2007 told the New Scientist that he questioned himself why the sun's activity had changed so much and doubted that solar influences were really a big factor compared to anthropogenic influences.
Split into simpler sentences: Lockwood 2007 told the New Scientist that he questioned himself why the sun's activity had changed so much. Lockwood doubted 2007 that solar influences were really a big factor compared to anthropogenic influences.