at any time in the past 800,000 years. since the beginning of the industrial revolution since the beginning of the industrial revolution at any time in the past 800,000 years. since the beginning of the industrial revolution since the beginning of the industrial revolution carbon dioxide level since the beginning of the industrial revolution carbon cycle has been altered traps heat since the beginning of the industrial revolution NASA Earth Observatory paleoclimate data on Earth’s geologic past. since the beginning of the industrial revolution nasa at any time in the past 800,000 years. paleoclimate data on Earth’s geologic past. at any time in the past 800,000 years. since the beginning of the industrial revolution since the beginning of the industrial revolution since the beginning of the industrial revolution