How Warming Temperatures are Changing the Seasons

Earth’s average temperature has increased by about 2°F since 1880 when measurement of the global surface temperature began. And the rate of increase has doubled over the last 40 years, from 0.14°F per decade to 0.32°F per decade. Given the size and heat capacity of the world’s oceans, it takes a massive amount of heat energy to raise the average yearly surface temperature even a small amount. Two degrees may not seem like much, but it’s had significant impact.

• Flowers are blooming half a day earlier each year, or a month earlier than 45 years ago. Unfortunately, pollinators such as bees have not been able to adjust their life cycles as quickly. Early blooming flowers don’t get pollinated and bees are left without food later in the season.

• As the planet warms and summer gets longer (hotter and drier, too), fall is getting shorter. The first appearance of fall color in maple trees now comes more than a month later than it did in the 19th century. And since the 1980s, many more leaves have been damaged by drought or insects, causing trees to drop those leaves earlier. A shorter fall leads to a longer winter, frequently with more storms and blizzards.

These changes have economic implications and raise long-term survival issues. In many areas, fall colors are a big tourist attraction. Not just decorative, the colors indicate that the trees are reabsorbing nutrients from the leaves into the wood, storing them for winter to be ready for spring. A shorter fall impedes that critical process.

Trees are adapting to rising temperatures by changing where they grow. For example, sugar maples already tend to favor the north. They’re likely to shift even further north in search of cooler temperatures. You’d better stock up on Vermont maple syrup now!