"Because Earth’s climate has changed naturally before, today’s warming is also natural."
What's actually true
Earth’s climate has always changed, and natural causes still affect it. But natural factors alone cannot explain the rapid warming observed since the mid-20th century. The evidence shows that human activities—mainly greenhouse gases from burning fossil fuels—are the main cause of recent global warming.
Where they have a point
They’re right that natural climate change is real, and a hot day or an unusual storm alone doesn’t establish what’s causing a long-term trend. The important question is what explains the warming we’re measuring now.
Say this (15 seconds)
You’re right that climate has changed naturally before. But that doesn’t mean every change is natural. Scientists have checked things like the sun and volcanoes; today’s warming is mainly from the greenhouse gases we’re adding.
Then ask
What kind of evidence would help us tell whether this warming is natural or caused by something we’re doing?
Sources
Pass the gravy (exit line)
Anyway, we don’t have to settle the whole atmosphere before dessert. Who wants pie?