In the forests here in Tennessee, instead of tracking foxes in winter snow, I spent February being startled by precocious bloodroot and other wildflowers piercing the leaf litter. Phoebes sallied after sun-warmed flying queen ants and spring azure butterflies. Japanese quince bloomed in garden hedges before January was over, multiflora rose broke bud on Valentine’s Day, and Mardi Gras came with Bradford pears in bloom. Then, in March: snow. A month after frogs sang through 70-degree evenings, freezes in the teens brought silence.

Time-lapse images of springtime’s advance this year look like a heat rash washing over a continent, south to north. The cold compress of last week’s storm is only a temporary salve. Spring came about 20 days early in the Eastern and Midwestern United States, according to the government’s National Phenology Network (phenology is the study of the seasonal timing of biological events). Even with the snowstorm, cherry blossoms a few steps from the White House and the headquarters of the Environmental Protection Agency are greeting the new occupants with startlingly early growth and blooms. According to the National Oceanic and Atmospheric Administration, February was the second warmest of the past 123 years in the contiguous United States, and the warmest ever in New York and 15 other states. NOAA predicts more higher-than-normal temperatures in the East and South in the coming weeks.

It’s not just children in the United States growing up in transformed seasons. Relative to just 30 years ago, satellite sensors report, the seasons are now changed over 95 percent of the earth’s land surface.

Not every species responds to climate change in the same way. Species newly arrived from overseas have genetic memories of other climates, giving them an advantage over the locals. The earliest plants to leaf out this year were privet, bittersweet and honeysuckle, all from Asia, and all able to tolerate ice on their young leaves. Climate change is predicted to give such introduced species a boost across the eastern United States: Kudzu is now headed to New York, hitching a ride as warmth moves north.

The phoebes that I watched migrate over short distances, breeding in the Eastern and Midwestern United States and Canada, then wintering in the Southeast and Mexico. This year they’ll take their cues from the plants and insects. If the warm trend continues, they’ll shift their own breeding forward, adapting to the changed season.