Berkeley, California - Two thousand California honey bees may have a story to tell. So too, more than 10,000 deer mice, and 3,000 oaks. Specimens of these plants and animals populate massive collections in Berkeley’s renowned research museums, and are now being enlisted as guides to past episodes of habitat and climate change.
Plant ecologist David Ackerly has calculated that some animals and plants would need to migrate as much as four miles a year to track their preferred temperature in a rapidly warming climate. Photo: Peg Skorpinski.
Researchers aim to piece together the fate of different California species and habitats dictated by shifts in weather patterns and climate over the last century. The “hindcasting” can help them develop and test models to forecast the impact of likely future climate change.
Changing climate, for example, is linked to reductions in the numbers of large trees across California, and a number of birds and mammals have moved upslope in the Sierra Nevada to higher, cooler elevations. These changes are expected to accelerate in coming decades, and pollinators, predators and other species will have to migrate or adapt in turn.
David Ackerly, a plant ecologist and professor of integrative biology, is one of the architects of the ambitious research effort — the Berkeley Initiative in Global Change Biology.
“The thing that has surprised everyone in this field is that data from studies around the world show the effect of climate change in just the last 50 years,” he says.
In 2009, to gain a sense of how environmental change can affect natural communities, Ackerly and colleagues developed a model to estimate the rate at which plants and animals would need to migrate in order to adapt to rising temperatures. The research generated eye-opening predictions, reported in the journal Nature.
Assuming a temperature increase of 0.05 degrees Celsius a year — or five degrees in a century — the scientists found that species in low-lying regions such as California’s Central Valley would need to migrate northward about four miles a year to remain in the same temperature regime that they had become adapted to over millennia.
In contrast to this startlingly high “velocity of change,” creatures and plants adapted to more rugged terrain could migrate much more slowly, since the higher, cooler elevations in mountains are only a short distance away.
It’s a sad calculation to confront, but in an era of rapid climate change, “our model shows that conservation of species in a rugged landscape would be a higher value investment than efforts in valleys,” Ackerly says.
Rising temperatures are only one potential pressure on ecosystems in the future. In California, changing fire regimes may pose an increased threat. Ackerly has begun collaborating with climate modelers at Lawrence Berkeley Laboratory to analyze the weather dynamics that generate “Diablo winds.” These little-studied warm air currents descend from the Coast Ranges in late summer and fall, generating hot and dry winds - classic conditions for California wildfires.
With seed funds from the Philomathia Center, Ackerly and his LBL colleagues will link historical weather data with climate models to help forecast the frequency, intensity and seasonality of these winds in a changing climate.
“It’s very difficult to go from global climate models to local weather, but we want to, and need to do this,” Ackerly says.
The links between environmental and biological change can be startling complex. Discerning the relationships calls for sifting through a growing blizzard of information to reach solid ground. Studies draw intensely on “big data” science, such as correlating regional and continental-scale temperature and moisture changes with vegetation patterns gleaned from remote sensing satellites.
To prepare for the future, Ackerly and eight Berkeley colleagues have launched a new NSF-funded initiative, “Environment and Society: Data Sciences for the 21st Century,” a training program designed to help graduate students develop the skills needed to take on large-scale and multi-dimensional research.
The program brings together students from computer science, biology and statistics to public policy, environmental planning and other fields, since progress in nearly all fields will increasingly require researchers to organize and integrate vast volumes of data and find otherwise unrecognized patterns and links. “Data is coming at a rate that no one can keep up with, but we have to tackle complex problems in an integrated way,” Ackerly says.
Ackerly has established a long-term research project to track changes spanning 20 years or more in oak woodlands at Pepperwood Preserve, near Santa Rosa in Sonoma County. In a set of 50 wooded plots, he has recorded the size, location and species of the dominant vegetation, from each Manzanita bush to every stringy sapling or gnarled, ancient oak. The work lays a foundation for multi-year studies of plant community change in natural ecosystems.
“Changes in distribution, density and vigor of plants in response to shifts of weather and climate are ongoing processes,” Ackerly says. “Maybe one percent of trees die in a year. It’s something we can’t see easily, but over 15 to 20 years, you really get a story.”
Clues to environmental change can come from unlikely sources as well. Berkeley global change biologists have examined honey bees from Berkeley’s Essig Museum of Entomology to track changes in food sources over time. A research team has sampled pollen packed onto the legs of bees collected from different regions of California over the past century. After running the pollen through an isotope facility, they have been able to distinguish the signatures of pollen gathered by the bees from wild flowers versus plants that fed on artificial fertilizers.
“The bees are the collectors,” Ackerly says. “We’ve been collecting the bees. Animals and plants - living, dying and dead - have a lot to teach us about the impact of climate change and how our familiar environment may change in centuries to come.”