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The author points out that much of what is known about modern climate change comes from advances in technology, including Earth-orbiting satellites. If that's the case, how are scientists able to tell current climate change trends are any different from other periods throughout human history?

1. They can't; score a point for climate change skeptics and deniers.
2. Ancient man was also quite advanced in technology and had other means available to measure their effects on earth.
3. Ancient evidence can be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks — paleoclimate evidence — which reveal current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.
4. None of the above.