Location: Providence, RI, U.S.A. The BIARI crowd in attendance today at Barus & Holley got a real treat: Dov Sax, an assistant professor of biology here at Brown, led "Climate Change and Biodiversity," yet another impressive and detailed discussion that's coming to seem like the norm for this program. The idea is simple: we know that plants and animals don't stay rooted in one place for all eternity - their populations move around the globe, so how will those movements change if the planet keeps getting warmer?
"10,000 years ago, a lot of the U.S. was filled with these giant lakes," Sax said, indicating a map of the western States showing many more bodies of water than most people reading this would expect. Personally, I never thought much about the name Death Valley, but it turns out the area was once teeming with life. This was one of many examples used to indicate that some species can adapt to changing conditions (like the very few fish left in Death Valley's shallow waters), others go extinct, and others move in tune with climate shifts. 
However, not all of these migrations are due north, Sax said: "Species do their own thing. They don't all respond the same way." The fossil record shows a common pattern where two species that once lived together follow very different paths--one moves dramatically away, while the other stays put in its original home. Sax's comments about human migration--such as over the land bridge that once connected Alaska and Asia--flowed well into the question of "what's a 'normal' system?" As humans crossed east, animals that we don't associate with North America crossed west, he said, from camels to elephants to rhinoceroses. "What's natural?" Sax asked. These easy-to-grasp anecdotes were grounded in hard data, such as the Intergovernmental Panel on Climate Change's prediction that by 2100 the Earth would warm between 1.1 and 6.4 degrees Celsius; during the last Ice Age, by contrast, the planet was at its coldest about 4 or 5 degrees C colder than it is today, Sax added. Different species would have different responses to this significant warming, and not all from the same original ecosystem would be able to deal with migration as well as the others. Human-made barriers such as cities or even agricultural land could prevent some species from finding cooler climes if they head north. So, how many species would face such obstacles and go extinct? 
The answer, Sax said, is very uncertain--but that's OK. He disavowed a paper published in Nature that claimed 15-37 percent of species would be "committed to extinction" by 2050. "That's totally wrong," he said. "The real number's something like one to eight percent, something much smaller." When a scholar in the audience questioned the range of these estimates, Sax enthusiastically rebutted that "scientists are really comfortable with uncertainty," even if the general public expects them to have clear black-and-white answers. "The more complicated the system, the less likely you are going to be able to make precise determinations," he said. Uncertainty has a particular place in the study of migration, he said, because the predominant models predicting how species will react to climate changes operate on the assumption that those changes are the only reason for differences in where animals live. The models don't take into account, for example, if a population currently lives in one place to avoid a predator or an unrecognized physical impediment to their survival. While discussing the effect of climate on humans, Sax half-jokingly suggested that now would be a good time to buy land in northern California and central Canada, because those areas may be the new destinations for humans seeking Los Angeles-style weather. As for the conservationist humans who are trying to help more species than their own, he said physically moving some species' populations may be the only way to save them. 
There are many limitations to human-engineered migration, he said, and not all biologists agree that this relocation/"rewilding" is a good idea. Some of them say the transplanted species could become too successful and wreak havoc on their new ecosystems, but Sax encouraged those approaching this topic to consider the risks: the alternative could mean extinction and a similar loss of natural balance elsewhere. He concluded this part of the presentation on a tenuous note, asking rhetorically about what would happen if a species needed to be transported across political boundaries. "Who knows how it's going to work out?" he asked. From there, Sax took a brief detour for the young scholars in the crowd, leading a how-to session on talking about research with the media and policymakers. His tips included avoiding jargon, anticipating how the audience would respond, and appreciating that people learn and think in different ways. Finally, he stressed the importance of preparation, telling the BIARI attendees to make sure to grasp the problems, benefits, solutions, and "so what?" behind their issue. "People will trust you more if you can say, 'Look, here's the good, and here's the bad,'" he said. 
Sax used this as a leaping-off point for an entertaining exercise that combined the day's two big topics. He brought two of the attendees to the front of the room and asked them to take dictation as the rest volunteered the costs and benefits of global climate change. The benefits included: milder climate, green jobs, more research, more rain, agriculture in new areas, rapid evolution, fewer droughts in some areas, new islands formed, and quicker travel time across the North Pole. The costs included: heat waves, more rain, loss of species, decrease in agricultural productivity, more droughts in some areas, high uncertainty, potential for political conflict, human displacement, war, and infectious disease. "It's likely going to be a very expensive proposition, but it would be silly to think that there won't be benefits as well," Sax said. "[However,] the ratio of costs to benefits is really out of skew." He added that not all of these effects would be felt equally or at the same time. 
"During the transition, everyone probably loses," he said. "If the climate ever stabilizes, though, then what happens?...In that scale, there will be winners and losers." From there, the conversation returned to the merits of human-managed relocation. One interesting point that rang true in my ears was Sax's claim that cute (or "charismatic") animals like the panda bear often serve as an "umbrella species" for other conservationist efforts. A campaign to protect the panda's habitat also protects everything that lives in its general vicinity. Of course, the traditional types of contemporary conservation efforts are likely to get trickier if not impossible in a warmer future. For instance, it's not certain that the climate will reach a set point after some years of change. It could keep warming to the point that humans would need to move some particularly vulnerable species every 30 years, Sax said. Furthermore, the priority afforded to conservation could change. Currently, the U.S. spends much more on maintaining the military-industrial complex than on saving endangered rodents. 
In the end, Sax said the networks being built at this BIARI could be good for both research and communication as effectors of change. After all, even with practice in dealing with policymakers and the media, "not all scientists are cut out to communicate with the general public," he said. "That's just the way it works."
