For the climate change skeptic: palm trees moving north

If watching An Inconvenient Truth was insufficient to convince you, then there's probably no hope for you. However, you can develop another spurious excuse after examining this interactive chart at Arborday.org. It shows the change in the Hardiness Zones in the continental United States - a lower number requires hardier trees - with a dramatic shift since 1990. Some of the Upper Midwest states have particularly strong shifts (made easier to see by the change from blue to green). If that's the change in just 16 years, what will 2022 look like? Palm trees in Iowa?