Our Climate Challenge

Global climate change is a real problem. But just what impacts will it have on the Chicago region? And what does it mean for nature?

by Jill Riddell

Here in the Midwest, we don’t see much of the drama of global climate change. While scientists issue dire predictions about the effects of greenhouse gas emissions and the media reports weekly on how it all really is happening, we in the Chicago region aren’t the ones observing polar bears floundering between ice floes. We don’t have glaciers breaking apart and melting in our backyards. Rising sea levels aren’t bound to swamp our homes.

Indeed, on Al Gore’s famous (and frightening) map in An Inconvenient Truth, Chicago appears to fare relatively well in terms of its projected long-term living conditions compared with other American cities. It shows up as neither scorched nor under water.

But Midwesterners are not immune to climate change. The signs here are more subtle, at least so far. Yet people who care about the Chicago region’s natural places are urgently seeking answers about how this worldwide phenomenon is affecting us — and how it will impact the fates of plants and animals in our own backyard.

What We Know

Earth’s surface temperatures are increasing. The unanimous declaration came in March 2007, when the United Nation’s Intergovernmental Panel on Climate Change concluded that the warming of the climate system is “unequivocal” and the probability that warming is caused by natural climatic processes alone is less than 5 percent. (This leaves greenhouse gas emissions from power plants, vehicles, manufacturing, and other sources as the principal culprit.) Some warming has already occurred, more is inevitable, and we’re driving it — this much is settled.

Where arguments flare is over how hot the earth will get and how fast, and what will happen in each region. For example, though the western United States shows temperature increases of two degrees Fahrenheit since the 1980s, some states in the northeastern and southeastern United States actually have become a degree or two cooler.

As for us, the Chicago region has measured a temperature increase of a half-degree since the 1980s, according to Illinois state climatologist James Angel. Models for 2100 predict a rise of between 2 and 12 degrees Fahrenheit. To put that in perspective, a 2-degree increase would put Chicago’s temperatures at about what Champaign, Illinois, is now. An 8-degree increase would cause Chicago to feel like southern Illinois. Twelve degrees would put Chicago at the approximate climate of Memphis, Tennessee.

Changing Local Conditions

In June 2008, the Chicago Wilderness Climate Change Task Force prepared a list of possible shifts of local conditions due to climate change. Drawing on a range of climate data and models, the task force determined that our region is likely to experience longer and hotter heat waves in summer. (The City of Chicago estimates that we could have as many as 31 days over 100 degrees by 2099 in a worst-case scenario.) We will have milder winters with fewer extremely cold days and less snow. Warming would lead to reduced ice cover on area lakes, including Lake Michigan, with generally warmer water temperatures.

The task force also considered changing patterns of rain and snowfall. Though more rain may fall overall, it may come as fewer rain events of greater intensity. More extreme weather events could lead both to severe dry spells and more floods. Water levels in streams, wetlands, and lakes might decline for most of the year, then swell up and flood during heavy rains.

Analyzing data from Midway Airport, James Angel notes that the Chicago region is currently in a trend wetter than the historical record. “Temperature is simpler to model because it doesn’t jump around as much as precipitation,” he says. “Precipitation is a lot harder to predict, even on a scale of what’s going to happen tomorrow. It’s not unusual for one area to get six inches of rain and another nearby to get a half-inch. But if I had to bet money on it right now, I’d bet Chicago will be on the wet side.”

Shift or Shock?

What would such changes mean to the Chicago region’s large network of natural areas and the life they support? First, every ecosystem is dynamic. Forest edges expand and retreat. Wetlands and bodies of water are fluid and changing. In fact, the local climate has changed dramatically in the last ten millennia. Two thousand years ago, the Chicago region was dominated by grasslands, supported by dry conditions and landscape-scale fires. Another ten thousand years before that, the landscape was cool, wet, spruce-dotted tundra.

So ecosystems can deal with change. But what happens when average temperatures shoot up over 20 years instead of 2,000? What happens when the conditions of the region shift to those of another in the span of one or two human generations? Can species adapt?

Climate change won’t spell trouble for every plant and animal species and every type of community. Some will respond well, while others will atrophy. “In general, affected species have three possible responses to global climate change, which can best be summed up as ‘change, move, or die,’” write scientists Robert Sullivan and Milt Clark in the CW Journal article, “Can Biodiversity Survive Global Warming?”

Ecosystems on the northern or southern edges of their range are likely first to be affected. The cypress swamps of the Lower Cache River in southern Illinois, which are at the northern end of their range, may fare well in the state. Volo Bog, at the southern end of bog country, may not. In mountainous regions, species may gradually move uphill where temperatures are cooler. That’s obviously not going to be the case here. “As flat as we are in Illinois,” says Brian Anderson, chief of the Illinois Natural History Survey, “our species shifts are going to be latitudinal — south to north — rather than altitudinal.”

Sullivan and Clark report that in the Great Lakes region, the ranges of red pine, black walnut, and sugar maple are expected to contract or expand as the region becomes hotter and, in some areas, drier. Creating predictive models for 134 tree species, Dr. Louis Iverson and Anantha Prasad of the US Forest Service concluded that oak-hickory forests would likely expand across the eastern US, while cooler-weather woodlands of maple, beech, and birch would contract. Northern spruce-fir forests may disappear altogether from the nation. Physiological ecologist Dr. Hormoz BassiriRad documented significant declines in the growth of mature oaks and oak seedlings due to climate change.

“It’s not all gloom and doom,” says Stephen Packard, director of Audubon–Chicago Region. Packard suggests that the trend toward sugar maple die-off might actually benefit the Chicago region’s threatened oak woodlands. Because of the suppression of natural fires, sugar maples are currently more successful reproducers than oaks. With climate change, maples might lose this human-created competitive edge.

“Many finely tuned species may get lost from small, finely tuned refuges,” says Packard. “But our prairie ecosystems and savanna ecosystems extend all the way down to Texas with a lot of the same species in them. We may need some new genes, new alleles. But we can get them. Land managers already restore. We’ll keep restoring. We may simply need to import some of our seeds from farther south.”

Still, research suggests that populations of even widespread species may have difficulty adapting to the climate shift fast enough. A plant population that adapts to the conditions in one part of the continent over thousands of years may perish before it can migrate or be transplanted, or may not have the genetic make-up to thrive in a new site. In 2001, Julie Etterson, then a doctoral student at the University of Minnesota, studied the partridge pea, a prairie plant that grows across North America. Planting seeds from Minnesota plants in Kansas and Oklahoma, she found that the newcomers to Kansas’ hotter, drier conditions (close to Minnesota’s predicted conditions in coming decades) produced 84 percent fewer seeds.

At the recent Chicago Wilderness Congress, Chicago Botanic Garden conservation scientist Dr. Pati Vitt discussed the federally endangered Pitcher’s thistle. Since it grows only along the shores of the Great Lakes, when its “bioclimatic envelope” shifts north of the lakes, as predicted, it will likely disappear.

Modern land development complicates matters still further. Even if plants are genetically capable of surviving swings in temperature and moisture long enough to move, their migration may be blocked by cities and vast fields of corn. It will be hard for a bog-loving species to locate another bog to love after the one it lives in grows too warm.

Weeds — those opportunistic plants that can easily take advantage of disturbed land — appear to be one group of plants with a leg up in the climate race. Capable of handling much of what both humans and an unusually unstable environment can dish out, they’re also able to move great distances in a short time. Kudzu, the “weed that ate the South” has already spread into 30 counties in Illinois. It has been found as far north as Evanston, where it inundated an acre along the el tracks.

In contrast, many native plants on the endangered species list suffer from small gene pools and exacting requirements for where they can or can’t live. Such conservative species will have to add climate instability to a growing list of hardships, especially as atmospheric changes appear to favor many of the invasive species with which they already struggle.

Animals

Animals will face serious challenges as well. Because of their already precarious position, amphibians are one group that has biologists worried. Worldwide, frog and salamander populations have been dropping precipitously for the past three or more decades. One hundred sixty-eight species have gone extinct. Habitat loss is the primary cause, but amphibians are sensitive to slight changes in temperature and moisture, and rapid climate change is unlikely to improve the odds of survival.

Locally, hydrological changes in Ryerson Woods Nature Preserve in Lake County have caused vernal pools to dry up so early in the summer that the water is gone before larval blue-spotted salamanders and wood frogs can transform to the stage where they can breathe out of water. Though extensive hydrological restoration work is being conducted at Ryerson to remedy the problem, similar troubles plague other natural areas in the Chicago Wilderness region. Hotter temperatures will make existing underlying problems worse, causing water to evaporate earlier and earlier in the year.

Temperature rises in larger water bodies may also wreak havoc. Sullivan and Clark assert that the most significant effects of climate change on wildlife will be on aquatic animals such as fish, as well as other species that depend on water for breeding and feeding, such as amphibians and waterfowl.

“With birds, there’s evidence in the Chicago area that migration is occurring earlier in the spring and birds are staying later in the fall,” says Field Museum ornithologist Doug Stotz. “Some southern birds have moved into the Chicago area. Tying that to climate change is a different issue, but I would say there’s plenty of evidence, in both migratory timing and distribution, that changes are occurring in birds.”

Deanna Zercher of The Nature Conservancy of Illinois points out that climate change may affect which native birds we see in our grasslands. She says that bobolinks, whose range centers to the north of us, may decline, while dickcissels, centered to our south, could become a more common sight.

A major concern is whether plants and the insects that pollinate them will remain in sync. If a particular flower blooms one week earlier every year, will its preferred pollinator also hatch out earlier, or will it lag behind on the old schedule? And how will that affect the birds that rely on those insect pollinators as a source of food during migration? Considering the interconnections within ecosystems, a small change could create a much larger ripple effect.

For all we are learning about the effect of climate change on local biodiversity, there is a faster-growing list of questions. INHS’ Anderson says scientists have barely begun to tackle the issue. “Very little local research is currently being done related to climate change,” he says. “A lot of the species-specific work that shows the impact of climate in other parts of the country is happening at high altitudes” where researchers see more pronounced climate effects. But research will be a critical tool for our region too.

Into the Future

The future is always uncertain, but swings in human population further complicate matters. The late Strachan Donnelley, founder of the Center for Humans and Nature, speculated that if conditions don’t deteriorate in Chicago as badly as in other parts of the country, the region could be inundated with people moving in from the flooded East Coast and drought-stricken West. A population boom would represent its own challenges: greater pressure to expand highways and housing onto open land, increased use of forest preserves, diminishment of aquifers, high demand for Lake Michigan water, an intensifying heat island effect from pavement and buildings, and so on.

Such scenarios have made climate change a top priority for leaders across governments, organizations, and disciplines. This September, the City of Chicago released an ambitious plan to cut Chicago’s greenhouse gas emissions 20 percent below 1990 levels by the year 2020. The longer term goal is to reduce emissions by 80 percent by 2050. Acknowledging the role climate is playing in nature, in 2007 the Chicago Wilderness alliance identified climate change as one of its four major initiatives.

Despite the many unknowns, leaders are urging immediate, sensible action. The mission of restoring and connecting ecosystems, creating migration corridors, and encouraging sustainable development has dominated the actions of Openlands, The Nature Conservancy, and other groups for more than a decade, but greater funding is needed now to get the job done quickly. More recently, Chicago Wilderness has created a “Green Infrastructure Vision” — a series of multi-layered maps and associated outreach efforts — to help local governments, land agencies, and communities connect natural lands across the landscape. As a final backstop, says the Chicago Botanic Garden’s Vitt, who curates the National Tallgrass Prairie Seedbank, biologists are busy collecting and preserving native seeds, to preserve plants’ genetic legacy in case we can’t act fast enough.

Humanity is now acting on many fronts to turn the massive ship of climate change around. Nature has many ways of adapting to the changes we create, but humans can increase nature’s chances of success by protecting large, varied nature preserves that will be more resilient to change. “Our goal is to manage natural areas in such a way that we keep the systems in place that keep the ecosystem healthy,” says Jane Balaban, a long-time steward in preserves along the Chicago River. “When you start with something healthy and in good shape, you fare better. You’re in position to respond to and be resilient in the face of what is coming. It’s more important than ever to do that.”

“It’s not all gloom and doom....We may need some new genes,new Alleles. But we already restore. We’ll keep restoring.”

— Stephen Packard, Audubon — Chicago region

Related Articles:

10 Years, 10 Trends, CW Winter 2008