Historical civilisations were very vulnerable to changes in local climate as they were heavily reliant on local food production, whereas we routinely ship food across oceans. Events like the [Little Ice Age](https://en.wikipedia.org/wiki/Little_Ice_Age) barely show up in the global climate record.
Earth's climate has varied greatly over time but its the current rate of change that is so alarming. During the last ice age it was about 4.5 degrees colder but it took 10,000 years to reach modern temperatures. We're currently on a path to changes of that magnitude within the next 70-100 years.
Earth's climate has varied greatly over time but its the current rate of change that is so alarming. During the last ice age it was about 4.5 degrees colder but it took 10,000 years to reach modern temperatures. We're currently on a path to changes of that magnitude within the next 70-100 years.