Deep Future

by Curt Stager

  Superficially, the Cape’s unusual fynbos may resemble the succulent, aromatic plant communities of dry habitats elsewhere, but there’s nothing exactly like it on Earth. The ancient plant assemblages that grow here evolved in isolation from other temperate regions and are incredibly biodiverse. A few minutes’ stroll atop Table Mountain, a short cable car ride up the sheer gray cliffs from Cape Town, introduces you to a rich array of otherworldly plants. Leafless epiphytes that resemble bright orange string hang in thick tangles from Protea bushes that produce woody cones and glorious colorful blossoms. A so-called three-day-blister bush resembles celery but raises vicious welts long after it’s touched; fortunately for hikers, it’s readily avoided if you keep a wary eye out for it. Tiny, insect-eating sundew plants no larger than a fingernail cling to dense cushions of green moss in the wetter areas. And the list goes on, adding up to thousands of species that are found only in this small patch of temperate habitat on the dangling tip of Africa roughly halfway between the equator and the South Pole.

  But it’s not just the physical isolation by tropical heat and deep-ocean waters that makes the fynbos into the unique botanical collection that it is. Rainfall plays a role, too. Any plant species that tries to join the thriving vegetational community on Table Mountain has to put up with winter chills and nutrient-poor sandy soils, but also with prolonged drought. It rains so infrequently there that water conservation measures are necessary for survival. These may include waxy coatings on foliage, liquid storage in juicy stems and fleshy leaves, or seasonal dormancy. But even these adaptations don’t make for easy living, and extra water rations from cool, damp fogs that drape the crests of the hills also help the hardy plants to make it from one rainy period to the next.

  Fynbos plants at the Cape of Good Hope, South Africa. Kary Johnson

  At tropical latitudes, rain is normally most abundant when summer heating drags the seasonal rain belt over the region, but in the South African Cape region there is another climatic mechanism at work. Westerly winds dominate the weather there, just as a matching stream of midlatitude westerlies pushes storm systems from west to east across the United States, Canada, and Eurasia. In most places in the northern and southern temperate zones, westerly winds can carry clouds overhead at any time of year, but in southernmost Africa it mainly rains in winter.

  By an accident of geography, the Cape region lies just barely within reach of ocean-fed rainstorms that ride the winds across the South Atlantic, and they come ashore mainly when winter cooling over Antarctica drives the encircling wind tracks farther north than usual. When the westerlies shrink back poleward during the warmer months of the year, most storms miss that marginal landfall and simply continue on across the southern rim of the Indian Ocean. As a result, the Cape experiences one major rainy season (winter) and one long, mostly dry season over the course of a year.

  What does Anthropocene warming hold in store for this place? Sea-level rise will gradually push the famous beaches farther inland and allow salty water to creep farther into coastal estuaries and settlements. Warmer temperatures will increase evaporation rates during the dry seasons and therefore add to the inherent aridity, and less of the winter precipitation at higher elevations will fall as snow. But these are not the only changes to come. Warming will probably hold the winter storms offshore for longer and longer periods, shrinking the duration and intensity of the rainy seasons more and more. Such a linkage between warming and drying is revealed in sediment core records of the last millennium that my associates and I have recently collected from South African lake deposits, and in a much warmer future, the winds may shift so far south that winter rains rarely strike the Cape at all. While most of Africa becomes wetter as global temperatures rise to thermal maximum, southernmost Africa is likely to take a different path and become drier than ever.

  Mike Meadows, a paleoecologist at the University of Cape Town, worries that if winters become shorter and drier, then South African water supplies could dwindle and cause problems for farms and towns, the wine industry, and the unique fynbos. “These plants can’t just lock arms and move all together to wetter locations,” he explained during my latest visit to his laboratory. “They’re tough and resilient, so some species may pull through just fine. But more drought-sensitive species might be lost.”

  It’s not just thirst that threatens the plants, most of which are already used to very dry conditions. It’s fire. “Less rain in the winter would lead to even drier soils and the woody vegetation would be more flammable in the windy summer when fires usually occur,” Mike continued. “This may lead to hotter fires that can cook the soils so much that they actually repel water when rain finally does fall.” Seeds would struggle to sprout, and the runoff would wash valuable topsoil away.

  Look around the rest of world’s temperate regions and you’ll find similarly unique, place-based stories unfolding in different locations. In southern Australia, as in southern Africa, people are worried about future drying and fire hazards. In the Alps, skiers and climbers are watching their beloved snow and ice fields shrink, and woody shrubs are moving uphill into alpine meadows. In the high, frosted Himalayas, a vigorous debate is under way among scientists; some fear that glacier retreat could bring water shortages to millions who live downstream, but others find little sign of such retreat and argue instead that the primary source of lowland river water is monsoon rainfall, not meltwater. In much of China, rain is expected to become more abundant overall, but the intensities of floods and droughts appear to be increasing. And nations that rim the Mediterranean Sea are concerned about thick, bottom-smothering globs of marine slime that are building up in the increasingly stratified waters, apparently more in response to rising temperatures than to other human influences.

  But there are surprises in the mix, too, a reminder that globally averaged patterns don’t capture the diversity of local-scale situations on the ground. A paper published recently by climatologist Alexander Stine and colleagues in Nature reported significant winter cooling in parts of Quebec and the southeastern United States between 1954 and 2007. This is seemingly at odds with the global situation, but it doesn’t negate it, either. A worldwide average is a composite of many locations, some of which may differ quite a bit from the mean. With Earth as a whole so obviously warming up, finding subsections of North America on a cooling jag can simply mean that other parts of the world must also be warming faster than the average (the western Antarctic peninsula, for example).

  In my own home region, the Adirondack Mountains of upstate New York, our main concerns differ from those of the dry South African Cape. Water is abundant here, and with the majority of computer models predicting slightly wetter conditions for us in the future, we tend to focus more on temperature-related changes and try to anticipate their effects on the tourism and winter sports industries that help to sustain our local economy.

  The Adirondack State Park centers on a Vermont-sized dome of ancient anorthosite rock capped by rugged peaks and sprinkled with tree-lined lakes. New York’s tallest mountain, our mile-high Marcy, towers over the northernmost headwaters of the Hudson River. Manhattan is a six-hour drive due south, and Montreal is less than three hours north. About half of the park’s 6 million acres are privately owned, and our patchwork landscape is a unique, invigorating blend of wilderness and humanity. I live and work in the northern sector at Paul Smith’s College, a small, rural school on the shore of Lower Saint Regis Lake, named after a nineteenth-century wilderness hotelier and entrepreneur. It’s an idyllic place to call home, and I enjoy it when people ask me what town I live in. I reply, “There is no town where I live.”

  Although I study climate change, most of my research deals with the distant past in general and the tropics in particular. Therefore, I didn’t spend much time studying Adirondack climates at first. In that sense, I was much like other concerned citizens who get most of their breaking news from the media. All I knew about local climate was that the weather around here seems to be unpredictable
, that it’s bloody cold in winter, and that our fiercest summer heat waves rarely hit triple digits.

  As global warming began to seep into public awareness during the last couple of decades, it was only a matter of time before someone published a compelling description of life in a hotter world that could be tailored to this popular neck of the woods. Bill McKibben, who lived in the central Adirondacks at the time, was the first writer to do so in a big way in 1989 with his groundbreaking book The End of Nature. His work gave an early preview of a possible future here: a once-diverse forest of mixed northern hardwoods and conifers devastated by warming, a place that rains instead of snows in January, a former wilderness disfigured by the stain of carbon pollution.

  At first, I was cautiously skeptical of such claims, as many of my paleoclimate colleagues were at the time. For us, climate change was about ice sheets bulldozing entire ecosystems off the map and natural hothouses keeping dinosaurs comfortable in the distant past. A couple of degrees warmer by the end of this century? Ha! That’s nothing. And how do we know that it’s really happening here? Global trends need not represent our local patterns accurately; show me the data for this location, and then I’ll believe you. Regardless of whether such a stance proves to be correct in the end, it’s the basis of healthy questioning; that is to say, the time-tested way of science.

  As luck would have it, I met and befriended Bill McKibben before I ever saw those convincing data. As a well-known park resident he was invited to join my college’s board of trustees during the 1990s, and he not only accepted the offer but took the post seriously enough to become personally familiar with our little school-in-the-woods. I enjoyed getting to know him, but I still wasn’t convinced by some of his claims of impending trouble. As a scientist, I wanted to see the numbers behind them but knew of no published Adirondack-specific weather data that could confirm or reject the existence of a major warming trend here.

  That situation soon began to change. Teams of scientists from various state and federal institutions were busy ratcheting the global picture down to the scale of national subregions by compiling weather records, evidence of changes in water bodies and woodlands, and more finely focused computer simulations to track regional climate trends and project them out to 2100 AD. If you live in the United States, then you may well have such a regional assessment available for your home region that can be found through a local university or with a simple online search.

  In 2001, one such group that was based at the University of New Hampshire published their findings in a report titled “New England Regional Assessment” (NERA). The group spread their findings widely in print and in person, touring to speak throughout the northeastern states. But despite their efforts most Adirondackers still encountered those findings mainly through interpreters such as Bill, who described some of NERA’s results in Adirondack Life magazine amid other gripping descriptions of our future. In that article we learned that warming is already under way here, that it will soon kill our sugar maples, replacing their brilliant autumn oranges and reds with the somber browns and dull greens of oaks and hickories that are now more typical of the Blue Ridge or Smokies, and that our winter sports industry will soon collapse as snowfall turns to rain.

  For those of us who love the harsh beauty of the North Country, imagining a winter without snow is like imagining cake without frosting. Winter here means critical tourist dollars, a shot at hosting the Winter Olympics again, white Christmases, skiing and snowshoeing and skating, an icy closing of the annual circle of the seasons, and a cherished prelude to springtime. Simply put, Adirondack winters are supposed to be snowy.

  In the hands of such a master wordsmith, this kind of imagery hits us hard in the gut. But Bill didn’t come up with the information himself; he merely handed it over to us in beautifully crafted prose. If you’ve been getting your own previews of impending change in your home region by this sort of indirect route, then you may also want to dig deeper into original sources to judge their accuracy.

  Bill gave me a chance to do that by asking my opinion about local climate trends as he prepared his Adirondack Life article. My response to his invitation was a welcome personal project that gave me an excuse to see how well NERA’s work stacked up against what I could find on my own. They hadn’t singled the park out for specific analysis and had instead lumped it in with other parts of New York state, but I suspected that this complex, mountainous area might not be following other places in perfect lockstep.

  I began by digging through my collection of geohistorical literature and soon found evidence to support the possibility of oaks and hickories dominating our forests in a hotter climate. In 1993, Syracuse University geologist Ernest Muller and colleagues published a description of ancient lake sediment from the warm Eemian interglacial that was exposed by a large mining pit at Tahawus, in the central Adirondacks near Mount Marcy. It was sandwiched between two layers of glacially deposited sand and gravel, and pollen grains extracted from it showed that oak, hickory, chestnut, black gum, and beech dominated the woods back then. All but the last kind of tree are common in the southern Appalachians but rare to absent in the Adirondacks today.

  If our greenhouse gases bring Eemian-scale temperatures back to these mountains, which appears likely even in a moderate 1,000-Gton emissions scenario, then history supports predictions of southern-style woodlands returning as well. That still doesn’t necessarily mean, however, that it’s going to happen during this century, or that such a change would be all bad from the point of view of future Adirondackers. Oaks and hickories have already lived here in abundance, so in the strictest historical sense they’re as native to these mountains as today’s trees. Oaks make acorns, which could help to keep bears, deer, squirrels, and other wildlife fed despite the current decline of beechnuts caused by beech bark disease. And I’ve traveled to the mountains of western North Carolina in order to enjoy the autumn colors with friends. It wasn’t as spectacular as what a more densely maple-studded landscape can offer, being rich in oranges, golds, bronzes, and muted reds but without so many of the brilliant scarlets and tangerine bursts that enliven more northerly scenes. Nevertheless, those colors still draw swarms of appreciative leaf-peepers to the southern Appalachians every year.

  My next task was to find out if the Adirondacks have really been warming as fast as NERA had claimed in its summary of northeastern climate trends. I enlisted the aid of a colleague, Mike Martin of Cedar Eden Environmental Consulting, who gathered the daily records of eight Adirondack weather stations from a database maintained by the National Climate Data Center. Several of the records showed moderate overall warming during the last fifty years and some showed slight cooling, but for all of them the most pronounced feature was their variability from year to year, month to month, and even day to day.

  No great surprise there. NERA’s own maps showed much of Maine cooling slightly while the rest of the northeast warmed, and the Adirondacks have some of the least stable weather conditions of any similar-sized patch of the lower forty-eight states. Local residents know this variability well, though they didn’t make a big point of telling that to outsiders as they coaxed a second Winter Olympics back to Lake Placid in 1980. Some readers may remember the January thaws that almost canceled the event that year. Having just helped to glaze the serpentine bobsled track at Mount van Hoevenberg with ice, I watched in frustration as it all melted away shortly before competition began. Fortunately, a lastminute freeze and timely snowfall saved the games in the end.

  An important discovery soon emerged from our number-crunching exercise, one that you’ll probably make yourself if you examine weather records from your own home region. Mike and I could find any kind of trend we wanted to amid the short-term ups and downs of interannual temperature fluctuations. It all depended on the time scales we chose to look at.

  For instance, let’s say that we wanted to support a frightening end-of-winter story. We could then choose a subset of time that began with a cool period and ended with
a warm one. The 1960s were relatively cool, so we could simply focus on the last four decades of the twentieth century in order to highlight an ominous trend rising from low to high temperatures. On the other hand, if we wanted to seem like pesky contrarians, we could instead show that a longer, fifty-year interval displayed a slight cooling trend overall. That’s because the early 1950s were unusually warm here, at some sites even warmer than the last decade was. A similar warm-coolwarm pattern is found in many other weather records from the northern temperate zone, and it helps to explain why some locations show average cooling over the last five decades. It’s like placing a long plank atop two widely spaced boulders; if one stone is larger than the other one, the board (trend line) will dip downward (cooling) toward the smaller stone. Choosing the hot 1950s as a starting point therefore obscures a more recent pattern of renewed warming that began in the 1970s.

  And another discovery soon followed. The midcentury Adirondack records differed quite a bit from the global pattern. Global average temperatures jumped during the 1940s, but the Adirondacks cooled slightly then, and the pattern reversed a decade later to produce that troublesome local warm spell of the 1950s. All the more reason to determine what the climate of your home region is really doing rather than assuming that it always operates in lockstep with the global average.

  I passed my results along to Bill, who reported some of them in his Adirondack Life article. They didn’t resonate well with NERA’s findings, though, and I smiled to see myself introduced to readers as one of the “few scientists left who aren’t convinced the climate is going to change dramatically.” But a much harsher response came after Mike and I published our results, which showed little or no fifty-year warming trend in local weather records. The article, which appeared in the Adirondack Journal of Environmental Studies, got us lambasted in the local paper by the head of an environmental group and a member of NERA itself, who apparently suspected us of being climate naysayers. The blowback surprised me, but it also goaded me to examine the Adirondack situation even more closely. As I dug deeper, I began to understand why it’s so difficult to find reliable descriptions of local-scale climate change in the mainstream media.