I've had that discussion several times with alarmists, even showing them graphs of the ice core data showing the cycle. It's like talking to a brick wall, they just ignore the data and shout about "consensus" and "science."
I've concluded it's not an issue that can be rationally debated because it is an identily issue, not a science issue. These are people who have believed in their DNA that mankind and industrial civilization somehow are destroying the world. Every theory that has come along that might prove it, from overpopulation, to fertilizers and pesticides, to nuclear weapons and power, has fizzled. Then, along came global warming, which fits their preconeived beliefs like a glove. Because it so well fits their beliefs and very identity as "progressives" "saving the planet" they will not look at any evidence that this is just another in a long line of junk science theories.