Earth Out of Sync: Rising Temperatures Throw Off Seasonal Timing

Global average temperatures continue to rise, affecting key life cycle events such as blossoming, migration and mating. Janet Larsen, director of research for the Earth Policy Institute, looks at how the changing temperatures and seasons are causing problems for plants and animals.
By Janet Larsen, Earth Policy Institute
April 2, 2010
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Milder winters have prompted growing numbers of some birds, such as the Canada goose, to skip migration altogether. The birds that don’t migrate are in danger of being wiped out by a sudden cold spell.
PHOTO: ISTOCKPHOTO/PAUL TESSIER


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A newly hatched chick waits with hungry mouth agape for a parent to deliver its first meal. A crocus peaks up through the snow. Rivers flow swiftly as ice breaks up and snows melt. Sleepy mammals emerge from hibernation, and early frog songs penetrate the night.

Spring awakening has long provided fodder for poets, artists and almanac writers. Even for a notoriously fickle time of sunshine, rain and temperature swings, some old-fashioned seasonal wisdom was consistent enough to be passed down through generations. The first blooming of a specific flower, for example, could traditionally signal when to find certain fish running the rivers, when to hunt for mushrooms, or when to plant crops. The timing of such seasonal events is coordinated in an intricate dance — a dance underappreciated, perhaps, until something jolts it out of step.

With global average temperatures up 0.5 degrees Celsius since the 1970s, springtime warming is coming earlier across the Earth’s temperate regions. A number of organisms have responded to the warming temperatures by altering the timing of key life cycle events. The problem, however, is that not all species are adjusting at the same rate or in the same direction, thus disrupting the dance that connects predator and prey, butterfly and blossom, fish and phytoplankton, and the entire web of life.

The timing of seasonal biological events, otherwise known as phenology, has been tracked in some places for centuries. Japan’s much-feted cherry tree blossoming has been carefully recorded since before 1400. The trees showed no clear trend in timing until the early 20th century, when they began to bloom earlier, with a marked advancement since around 1950.

The meticulous records of Henry David Thoreau help us gauge how spring has changed in Concord, Mass., since the mid-1800s. Comparing his notes on over 500 species and subspecies of plants with modern surveys and records in between, researchers found that springtime blooming advanced by an average of one week over the past 150 years as local springtime temperatures rose.

The plant varieties that advanced their timing appear to have thrived over the years, while others declined in numbers. The varieties left behind include asters, mints, orchids, lilies and violets. Some native plants advanced their blossoming dramatically: the highbush blueberry by three weeks and the yellow wood sorrel herb by a month. Yet these native plants may be the exception rather than the rule. On average, non-native invasive plants advanced their bloom by 11 days more than natives. With exotic invasives appearing to adapt more quickly to warming temperatures, the concern is that they could outcompete some native plants, leading to their disappearance.

Earlier springs and later autumns mean longer growing seasons — as long as plants do not succumb to a surprise late cold snap or wilt in the peak summer heat. In Germany, apricot and peach trees now bloom more than half a month earlier than in 1961. Apple trees in the northeastern United States moved up flowering by eight days between 1965 and 2001. Apple trees require chilling time before they flower, and warmer winters have been tied to smaller harvests. Earlier spring blooming has lengthened pollen seasons in some places by weeks. Allergy sufferers beware: This trend is likely to get worse as the planet gets warmer.

A longer growing season could benefit some crops, such as the sugar beet. For other foods, however, including important cereals such as rye, the increased early-season temperatures could hurt yields by pushing plants to devote more energy to vegetative growth than to the seed that we eat. The premature warming also elevates the risk of damage from late frosts. In 2007, for example, a warm March in prime U.S. agricultural regions pushed spring into gear early, only to be followed by unusual cold in April. The damage to the nascent crops exceeded $2 billion.

Exactly how these changing plant communities will interact with pollinators and foragers that may or may not be changing at the same pace remains unanswered. Members of the animal kingdom are responding to warming in different ways. A quintessential early bird, the American robin, now sometimes makes an even earlier springtime debut. In the Colorado Rocky Mountains, where robin migration is not just south-to-north but also up to higher elevations, the birds have responded to warming in their wintering grounds by traveling to their high-altitude summer breeding grounds two weeks earlier in 2009 compared with the early 1980s. In some years the robins arrive long before the snow has melted — making it far more difficult for this early bird to catch the worm.

For pied flycatchers that breed in the Netherlands, migration timing from their West African wintering grounds has not changed, but earlier spring warming has caused the birds to breed about as soon after their arrival as possible. Unfortunately, their caterpillar food has been able to respond even more strongly, advancing hatching in one woodland by an average of 15 days over two decades, while the birds only advanced by 10 days. At sites where the caterpillar populations still peak somewhat late, flycatcher populations have dropped by 10 percent, but where the caterpillars have advanced hatching the most, flycatcher populations have plummeted about 90 percent.

Across Europe as a whole, populations of birds that did not advance their migration time along with earlier spring warming have shrunk since 1990. Short-distance migrants seem to be faring better than those traveling long ways. Milder winters have even prompted growing numbers of some birds, such as the Pacific brant and Canada goose, to skip migration altogether. Like the early crops, however, the birds that stay are in danger of being wiped out by a sudden cold spell.

As evidenced by the caterpillars in the Netherlands, short-lived insects have some of the fastest life cycle responses to global warming. In Central Europe, where almost every summer since 1980 has been hotter than the long-term average, warming has allowed some species of butterflies and moths to become active earlier and actually add an extra generation in the year — something not seen among those species in records dating back to the 1850s. If predation does not increase, a population explosion could overstress the plants that the butterfly and moth caterpillars eat.

High-altitude mountain pine beetles in western North America present a similar case. In warmer weather, they can complete their life cycles in one year instead of two. Insects that once were active for just two weeks a year now can be found flying for up to six months, leaving devastated forests in their wake. Earlier springs and milder winters are also linked to an increased incidence of tick-borne encephalitis and other diseases spread by insects that do well in the warmer conditions.

In addition to or instead of adjusting life-cycle timing, some organisms have responded to warming temperatures by shifting their geographical ranges, often poleward or upward. Bird and butterfly range shifts averaging 6 kilometers per decade have already been observed, with some species moving quite faster. There are, of course, limitations to all these adaptations. Species that are even more mobile can gain only so much altitude before running out of mountain or can travel only so far before becoming blocked by pervasive human development.

Some wildlife take their timing cues from environmental factors other than temperature. The snowshoe hare, for instance, appears to rely on changes in day length to signal when to transform its coat color from winter white to summer brown. While day-length patterns are the same from year to year, snow in the hare’s Montana wilderness habitat now melts up to a month early. If hares are not able to speed up their coat change, they will be in trouble: A stark white hare on bare ground is a remarkably easy target. And as go the hares, so go the lynxes that feed almost exclusively on them.

Tinkering with an incredibly complex and interconnected system is fraught with risk. These mismatches are just some examples of how a hotter world is a world unlike any we have known. It is still too early in this global experiment to tell which creatures will be the climate winners and losers, but the signs indicate that the losers will be the majority. Turning down the global thermostat by cutting greenhouse gas emissions is the only way to avoid the risk of throwing nature further out of sync.


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Post a comment below.

 

B_14
6/10/2010 3:27:51 PM
It's amazing that so many people continue to insist that global warming is a myth, hoax, or a conspiracy. What would be the point of that? Change is hard, but is required by the reality of global warming. Why would so many people "conspire" to perpetuate a "hoax" that only makes life harder? It's not money. Except Al Gore, almost no one is getting rich off of global warming. Conversely, those currently in power and money with the way things are (oil and car companies e.g.), have quite a lot of motivation to call valid science "just a theory." And then everybody who simply doesn't want to have to pay more for gas, or use less electricity, or eat more locally, etc., jumps on board calling it a "myth," or "hoax." But a "religion?" Seriously? (warning, sarcasm follows) Yeah, sure, global warming is a religion. With no deity, no churchs, no clergy, no theology, and no mysteries. Some "religion." (this concludes the sarcasm for this comment) It's also truly amazing that the same tired excuses continue to be trotted out to supposedly argue against global warming. "But what about the Ice Age?" "But temperature has always fluctuated!" "But humankind can't have any significant impact!" "But the Earth is cooling!" All of which show pretty much zero understanding of the science involved, and of Earth science in general. And Ray, "Google the e-mails from England and PA?!" Those places aren't even mentioned here. Do you have any idea what you're talking about? Any?

Lisa_1
6/7/2010 9:05:07 PM
We are bee keepers in CA and we have noticed that bee swarming season has been greatly effected by the changes in our weather. While this article says that the weather is warming we have had very cold spells this spring. It will warm for a day or so and then be below freezing or very cold for a few days. This dramatic fluxuation is very hard on a swarm. A swarm has three days to find a home before they die. If they find one they do not have the food to survive a cold spell. For bees that are rescued by beekeepers we can adjust by feeding them so they can at least survive but it still takes its toll. I have spoken with several bee keepers in our area and none of their hives have their normal storage of honey for this time of year. We will have to watch them because they may not be able to survive the winter if they don't have enough to stay strong and eat throughout the winter. Not to mention the human effect of paying more for honey due to shortage. So whether the trend is cooling or warming or it is all a hoax, animals are being effected by the erradict weather conditions whatever you believe the causes are. Thank you for this article.

Michael_82
6/7/2010 5:09:35 PM
The fact is we WERE headed towards an ice age, but humans dumping greenhouse gasses have not only halted the coming ice age, but has reversed it!

Melanie_18
6/7/2010 11:08:30 AM
Thank you for this article. It's unfortunate that there's so much corporate-funded propaganda out there masquerading as fact or news. Apparently, that has quite an effect on critical thinking abilities. This is the sort of information that those of us who've been living the "Mother Earth" life for years can add to with our local documentation. As climate changes more drastically, we'll need shared solutions just as drastically. Again, thank you.

Ray_23
6/7/2010 9:14:52 AM
This is a great site, so why do you include articles like this? Run a Google check on the emails out of England and PA, they knew the "data" was false, and even said they would delete it all before the admitted it. Global warming is a religion. Believe in it if you like, just don't call it science.

Vicky_12
6/7/2010 8:31:08 AM
Temperatures are NOT rising; it is very well documented that it is cooling. Temperatures fluxuate and will continue to fluxuate. This is an article to push her agenda. People are starting to realize the Climate "Hoax" documented recently and are opening their eyes. Only if we can reach our children and stand against the schools to educate our children correctly instead of perpetuating the "hoax." We need to be good stewards of our environment, but do it with common sense.

Rick M_2
6/7/2010 8:10:45 AM
I find so hilarious, is the delusion of well documented. We the people have so many conflicting theories and beliefs with everything in this world. If this "Theory" is true, how do you explain the last ice age? The loss of the huge dinosaurs? and all of the species that were extinct BEFORE man came the dominant common denominator? Crap stories like this only propagate one side of story. Global climate changes have occurred for millenniums, without human contribution. This global farce is all about the money and economics associated with it. Have you even looked at the TRILLIONS of dollars involved? Wouldn't you feel even more betrayed if in the future you discover that the "HUMAN" contribution was less than 5% of the change? If you print stories like this, I would think that you could give alternate theories an opportunity to publish their works. I am a true believer in conservation, but this goes WAY BEYOND common sense and stupidity. Oh, but the way, how'd you like that pandemic/epidemic swine flu kill last year?

Fran Tracy
6/7/2010 7:38:42 AM
The temperature has always fluxuated and it will continue to fluxuate. The theory that man can affect it with his actions is not reasonasble. The dust and ash put off by the volcano in Greenland or Iceland is putting more polution in the astmosphere than all the greenhouse gasses man makes. Using resources wisely makes sense but the millions of dollars a few people like Al Gore has made is outrageous. we need to let people make a good living and not regulate so it makes it impossible to afford gas or heat our houses. Fran

MC_2
4/5/2010 5:51:32 PM
1) We'll have to wait for history to tell us whether it's ridiculous or not. Personally, I'd feel more ridiculous if man-made climate change turned out to be real and we had not acted than if it turns out not to be real once we have. 2) The singular of species is, well, species. Kinda like fish or deer. Sorry-- I never get to use the cotton-pickin' English degree for anything else. 3) While we worry about climate change, Bildebergers, and the nefarious plots of the New World Order, the existing world order bilks us out of whatever wealth we might have had and pats themselves on the back while they watch us argue over who's to blame for what. You know, when we should be deciding what to do in the absense of any real leadership. 4) Why are we even worried about it???? Magnetic shift is going to kill most of us anyway, thereby solving the problem.

eicebleu
4/4/2010 9:59:00 AM
Hardly ridiculous. This phenomena is well documented by Science. Thank you for posting this. I'd been reading about particular species here and there--one specie at a time. This is the first time I've seen so many compiled together. Still, nobody likes to hear bad news. We're fighting human nature to plug one's ears when hearing something one doesn't like.

Doug Cresse_2
4/4/2010 5:41:00 AM
This is a great website Why do you print such ridiculous articles as this?








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