Exploring Future Flora, Environments, and Climates Through Simulations (EFFECTS)

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Climate changes can significantly affect species and ecosystems. Historical and paleoenvironmental data record species and ecosystem responses to past climate changes, but these records become sparse as one goes further back in time. Model simulations can be used fill the spatial and temporal gaps in observed records to improve our understanding of the potential magnitude, rate, and spatial expression of species and ecosystem responses to climate change. This research uses state-of-the-art climate simulations and numerical models to better understand both past (paleo and historical) and potential future climate change effects on species and ecosystems, with a focus on vegetation. Improving our understanding of how vegetation has responded to past climate changes can help us to identify the potential vulnerabilities of vegetation to projected future climate changes. The results of this research are used to inform conservation and natural resource management efforts.

The EFFECTS Project is a research activity of the U.S. Geological Survey (USGS) Geosciences and Environmental Change Science Center and receives funding from the USGS Climate Research and Development Program. 

Species and Ecosystem Responses to Climate Change

LPJ simulated vegetation

LPJ simulated vegetationVegetation was simulated for (A) 1961–1990 using CRU TS 2.1 climate data and for (B-F) 2070–2099 using climate projections from CCSM3, CGCM3.1(T47), GISS-ER, MIROC3.2(medres), and UKMO-HadCM3 coupled atmosphere-ocean general circulation models (AOGCMs). PFT = plant functional type. (Figure 4 from Shafer et al. 2015, https://doi.org/10.1371/journal.pone.0138759.g004)(Public domain.)

Future climate changes may significantly affect species and ecosystems. Changes in climate can alter species distributions and affect a variety of ecosystem processes, ranging from carbon storage to wildfire regimes. Historical records can help us understand how species and ecosystems have responded to climate changes over the past few centuries, but these records cover relatively short time periods. Paleoenvironmental records, such as pollen in lake sediments, may extend further back in time (e.g., thousands of years) but these records are often spatially sparse. We are using numerical models to simulate vegetation responses to both past and potential future climate changes. Models are useful because they can simulate time periods when data are either limited (e.g., past time periods) or not available (e.g., future time periods). They also can be used to simulate the effects of climate change for regions that lack observed data. Model simulations allow us to test hypotheses about the potential mechanisms and climatic controls of past vegetation responses to climate changes. Determining how vegetation has responded to past climate change is important for understanding how vegetation may respond to potential future climate change.

We are using models to simulate vegetation changes during past periods of rapid climate change, such as the changes that occurred ~15,000-10,000 years ago in North America. Important vegetation changes during this time period included shifts in northern tree lines, the movement of temperate species at mid-latitudes to higher latitudes, and interactions between climate, vegetation, and wildfire occurrence. We compare the magnitude, rate, and spatial patterns of these past vegetation changes with simulated vegetation responses to potential future climate change. The results help to identify the main processes controlling vegetation responses to climate change and the species, ecosystems, and geographic regions that may be particularly sensitive to potential future climate changes.

Implications of Climate Change for Conservation and Natural Resource Management

Conservation and natural resource managers require information about how climate changes may affect the species and ecosystems they manage. This research simulates the potential effects of future climate changes on species and ecosystems of management concern. The results of this research aid conservation and natural resource managers in developing adaptive management responses to potential future climate changes.

Methods and Models

We use process-based vegetation and environmental models to simulate species and ecosystem responses to climate change over paleo (e.g., the last ~21,000 years) to projected future (e.g., through 2100 CE) time scales. As input data for our models, we use climate simulations from various sources, including simulations produced as part of the Paleoclimate Modelling Intercomparison Project (PMIP) and the Coupled Model Intercomparison Project (CMIP). Vegetation is simulated using both equilibrium and dynamic vegetation models, including BIOME4, LPJ, and LPJ-GUESS. Modeling and analyses are done using a variety of programming and scripting languages, including Fortran90, C++, and NCL (NCAR Command Language). The model simulations and related analyses are run on high performance workstations with multiple processors (e.g., dual 18-core) and large amounts of memory (e.g., >150 GB). Model input and output data are stored on large disk arrays. Our research data sets are made available to the public via USGS data releases.