Home Energy and Environment Are Leaves “Turning” Already?

Are Leaves “Turning” Already?


I’ve seen a ton of tweets & Facebook posts in the last couple of weeks from friends in the mid-Atlantic remarking that the leaves are “turning” already. Is fall foliage arriving early?

What I’m seeing right now in my Falls Church neighborhood isn’t leaves turning — they’re dropping dead. There’s a big difference between leaves gradually turning yellow, orange & brown while on the tree, then gently floating to the ground … and leaves turning brown & immediately leaping to the sidewalk. My neighborhood features green trees with brown leaves lining the gutters. Not exactly prime leaf-peeping.

Why are they dropping so early?  

A scientist friend explains:

The leaves dropping is mostly because of the dry summer, but this summer’s record heat also means the trees require even more water, making the same level of drought more severe than it would have been without the high heat. I’m hoping what we’re seeing is the trees going into early dormancy, rather than signs of long-term damage.

Why do people assume any brown leaves after Labor Day are fall foliage? Part of it is an issue of transplantation. Many of us grew up in places up north where hints of fall foliage right now wouldn’t be unusual. But here in the mid-Atlantic, it’s way too early for true fall foliage — we’re still technically in summer.

Of course, this debate is a blip on the radar compared to what’s facing New England. Why would tourists spend thousands to go leaf-peeping there if global warming makes it too hot for maple trees, the main source of New England’s brilliant autumn colors?

Cross-posted from The Green Miles

  • blue bronc

    As your scientist friend puts it, no water and lots of heat dries up the capillaries. There are a few trees with leaves doing a short color change, but many are just shedding the leaves.  

    This is the extremely simplified version:

    The high heat causes the vascular system of the trees, and other plants to put the evapotranspiration cycle in high. I used Wiki link because it is a good explanation of the cycle.  But due to the somewhat lower amount of water available this year there was a reduction in the amount of “food” in the leaf structure, which reduced the amount of color change. And, then the leaf fell off brown and shriveled.

  • VaPolitico

    and the sky is gray.  I’ve been for a walk, on a [summer’s] day.  

    Maybe the Mamas and the Papas just got the lyrics wrong back then 😛

  • Dan Sullivan

    Just another day in tornado alley.

  • Dave

    Global warming is a serious threat to our globe being caused by man-made industrial pollution. This is scientific fact.

    But… it’s rather unscientific to point to any one localized weather pattern – say, a dry, hot, summer on the East Coast – and call it an effect of global warming. It’s an El Nino year, and they tend to be dry and hot towards the end of summer. They also tend to have warmer, wetter winters, which leads to things like the massive amounts of snow we had.

    Again, I regularly take issue with pointing to specific weather patterns and pinning them on global warming. This is one data point in a trend. Doing this almost diminishes the real impact of global warming – the fact that it’s global. RK once gasped at an 80-degree day in January, and I gave the same finger-wag then.

    I’ve said it before on this blog, and I’ll say it again. The concern is not with a dry, hot summer. It’s not with a 90+ day. Those happen. The concern is that the average temperature during that dry, hot summer was a degree higher than the last one, and that there was one more 90+ day than normal. The concern is that the next one will be a degree higher on average than this one and have one more 90+ day, and so on. It’s not that there’s an 80-degree day in Jan., but rather that the last one was 79, and the next one will be 81.

    The reason this whole issue is not a debate is because science is firmly on one side. So let’s stick to the science. Fall leaves are a fun way to get peoples’ attention, but not a good way to make this point.