By Marlene Cimons
For many, the winters we remember from childhood are becoming just that: memories. Winter’s record warmth in recent years — especially the shockingly high temperatures during the first months of 2016 — has become a frightening harbinger of a world to come.
Along with shorter and warmer winters, many areas also are experiencing earlier-than-normal springs, or “false’’ springs, and sporadic hot summer-like days, a climate pattern that can produce chaos with the Earth’s ecosystems.
“In the more than 30 years I’ve been a meteorologist, I’ve always enjoyed sitting down each day and taking a look at the latest computer model forecasts of the weather for the upcoming ten days,’’ said Jeff Masters, director of meteorology for the site Weather Underground. “That pleasure began becoming tinged with anxiety beginning in 2010, when we seemingly crossed a threshold into a new more extreme climate regime. The relatively stable climate of the 20th Century that I grew up with is no more.’’
Thus far, this year alone has been particularly astonishing.
Data released earlier this month from NASA shows February with record-breaking warmth — the warmest February on record and the warmest seasonally adjusted month in recorded history. This February was 0.5 degrees Celsius warmer than the previous hottest February on record — a significant amount, as record temperatures are typically measured in hundredths of a degree — and was 1.35 degrees Celsius above the 1951-1980 average. Overall, this past December — February was the hottest meteorological winter on record.
The significance of these high winter temperatures reaches beyond humans’ connection to the changing of the seasons, or nostalgia for snow days and sledding. Moreover, while some people may welcome the chance to stop scraping off their car windows in the morning in favor of early blooming daffodils, the consequences of these new winters could prove dangerous to ecology’s fragile balance.
“February was a taste of what our future looks like in a more-than-2 degrees C warmer world — the Northern Hemisphere was about 2.5C warmer than the pre-industrial baseline — if we do not rapidly ramp down our burning of fossil fuels,’’ said Michael Mann, a climate scientist who directs the Earth System Science Center at Pennsylvania State University. “The damage is limited when this only happens for one month. But if this level of warmth becomes persistent — as it will if we don’t act — then we will start to see some of the more damaging and potentially irreversible impacts of climate change.’’
Dangers for humans and the environment
A warming climate will likely lead to more early springs and “false’’ springs, the latter prompted by unusual temperature spikes followed by cold snaps. “In some regions, living things get fooled into think spring has arrived, trees sprout, eggs hatch, etc., only to suffer another winter-like cold outbreak, potentially damaging or killing the ‘fooled’ organisms,’’ Mann said.
In one study, for example, a false spring in 2012 caused $500 million in damages to fruit and vegetables in Michigan. And in the Washington, D.C. region, where cherry blossoms are an annual tourist draw, a predicted drop to freezing temperatures and snow this weekend — soon after an exceptionally early burst of warm temperatures — threatens the vulnerable blossoms as they enter a delicate growth stage.
To be sure, an earlier spring, for some, “could be seen as a good thing,’’ said Andrew Allstadt, a postdoctoral fellow at the SILVUS Lab at the University of Wisconsin-Madison, who authored a study last year on climate change and early spring.
“A longer growing season would generally mean high plant productivity, at least ignoring other associated climate effects like hotter temperatures in the summer,’’ he said.
But a change in the timing of spring plant resources could harm the species that depend on them, such as long distance migratory birds, he said. “They decide to migrate based on cues in their winter habitat, such as day length,’’ he said. “They do not know when spring will arrive in their breeding grounds, and the birds may arrive too late for resources they need to reproduce. There is already evidence that birds that have adapted their migration timing are doing better than those that have not.’’
Also, many insects time their emergence in the spring to the flowering of leaves and flowers. “But, since they have evolved to respond to slightly different environmental cues than their host plants, changes in spring temperatures have led to a reduced coincidence among some plant-insect interactions,’’ Allstadt said. “This may be good in some cases depending upon the insect and your point of view, with perhaps fewer pests in some cases. But insects play many roles in an ecosystem, including as an important food source for other animals.’’
Cold temperatures also are necessary to kill many insects, including pests and those carrying illness-causing pathogens. “Some places will no longer have a good frost, and that is what kills off a lot of bugs and some diseases, things like fungal diseases and rusts,’’ said Kevin Trenberth, distinguished senior scientist in the climate analysis section of the National Center for Atmospheric Research.
Pine beetles are one example, he said: The insects are destroying vast swaths of North American forests, thanks in part to changes in winter temperatures — cold winters used to kill off many pine beetles, but now, as winter temperatures rise, more and more beetles are surviving through the winter. Changes in winter weather can also make it easier for disease-carrying mosquitoes, like those that carry the Zika virus, to thrive.
Moreover, many plants and insects need cold temperatures during the winter to begin to break dormancy. “Many fruit trees require a certain number of hours of exposure to temperatures below freezing or else they won’t flower, so loss of winter would be bad for them,’’ said David Inouye, professor emeritus of biology at the University of Maryland, who studies the impact of climate change on the environment.
A way of life, shifted
Warmer winters mean cultural changes too. A 2014 study predicted tough times ahead for the winter Olympics as the planet warms and snowfall amounts dwindle. This year, in fact, organizers of the Iditarod, a 1,000-mile dog sled trek across Alaska, hauled in snow by train to compensate for nature’s lackluster performance, and to ensure the trail was ready for the event.
“Many ski areas are already starting to worry about the loss of snow in the winter, [and the prospect of] a shorter ski season,’’ Inouye said. Also, “winter snow creates an important reservoir of water that keeps streams flowing in the summer for summer recreation – kayaking, rafting, fishing – and irrigation for agriculture.’’
Snow also serves as a critical water source. “Snow is a way to save water from times when not needed for late spring when it is,’’ Trenberth said. “So having ways to manage water will be a major key.’’
The impact of winter’s transformation on the human psyche likely will be gradual, but, if present trends continue, inevitable. …