There has been much speculation about the earth growing warmer, possibly due to human activity. Would such a warming trend be manifested by a decrease in the length of winter (and a consequent increase in the length od fall and spring)? I live in Southern NE (around the latitude of Boston), and it appears that the end of autumn (as measured by the date when the leaves drop)is moving out. I remember back in my childhood-the leaves would start to drop in late September, with the trees mostly bare by mid-October. Now, the leaves begin to fall in mid-October, and we still have some hanging on into late November?. I understand that trees drop their leaves based upon the decreasing hours of daylight, so warmer falls should not change anything. In any case, if global warming is real, how long willit be, before we in the northern hemispere should notice a drastic change?
That sounds wrong to me.
Deciduous trees in Southern states drop leaves based on the angle of the sun, not the cold, since otherwise they would remain green year round.
The National Assessment’s a good place to start for info on the potential impacts on the US:
http://www.usgcrp.gov/usgcrp/nacc/default.htm
That doesn’t help with the tree question as much but does give good general information about all the types of impacts that might be expected.
I do know the color of fall leaves is affected by temperature, so it may be that the trees still prepare themselves based on the hours of sunlight, but the rate at which chlorophyll degrades and the leaves drop off is affected by the temperature. Water availability might also play a role. That’s just a WAG though.
Please restate the question in less ambiguous terms. As I understand it, the seasons are defined by the relative positions of the sun and earth, and all 4 seasons are equal in duration.
If you are defining “season” in relation to when the leaves change color, then it seems that you have already noticed a change in the timing, and have already answered your question.
And some deciduous trees drop their leaves depending upon how much water they get. California Buckeyes (Aesculus californica) tend to drop their leaves by mid summer, unless they have a constant supply of moisture.
As to fall color, here in Monterey, the trees dont always lose all of their leaves until sometimes late winter, and i’ve seen Liquidambars with leaves FINALLY turning color in late winter.