Harvard University Center for the Environment Scholarly Articles

Permanent URI for this collectionhttps://dash.harvard.edu/handle/1/22419513

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    Global Surface Temperature Response to 11-Yr Solar Cycle Forcing Consistent with General Circulation Model Results
    (American Meteorological Society, 2021-04) Amdur, Ted; Stine, Alexander; Huybers, Peter
    The 11-year solar-cycle is associated with a roughly 1 W m-2 trough-to-peak  variation in total solar irradiance and is expected to produce a global temperature response. The amplitude of this response is, however, contentious. Empirical estimates of global surface temperature sensitivity to solar forcing range up to 0.18 K [W m-2]-1. In comparison, best estimates from general circulation models forced by solar variability range between 0.03-0.07 K  [W m-2]-1, prompting speculation that physical mechanisms not included in general circulation models may amplify responses to solar variability. Using a lagged multiple linear regression method, we find a sensitivity of global- average surface temperature ranging between 0.02-0.09 K [W m-2]-1, depending on which predictor and temperature datasets are used. On the basis of likelihood maximization, we give a best estimate of the sensitivity to solar variability of 0.05 K [W m-2]-1 (0.03-0.09 K [W m-2]-1, 95% c.i.). Furthermore, through updating a widely-used compositing approach to incorporate recent observations, we revise prior global temperature sensitivity estimates of 0.12 to 0.18 K [W m-2]-1 downwards to 0.07 to 0.10 K [W m-2]-1. The finding of a most likely global temperature response of 0.05 K [W m-2]-1 supports a relatively modest role for solar cycle variability in driving global surface temperature variations over the 20th century and removes the need to invoke processes that amplify the response relative to that exhibited in general circulation mod els.
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    Merging paleobiology with conservation biology to guide the future of terrestrial ecosystems
    (American Association for the Advancement of Science (AAAS), 2017) Barnosky, Anthony D.; Hadly, Elizabeth A.; Gonzalez, Patrick; Head, Jason; Polly, P. David; Lawing, A. Michelle; Eronen, Jussi T.; Ackerly, David D.; Alex, Ken; Biber, Eric; Blois, Jessica; Brashares, Justin; Ceballos, Gerardo; Davis, Edward; Dietl, Gregory P.; Dirzo, Rodolfo; Doremus, Holly; Fortelius, Mikael; Greene, Harry W.; Hellmann, Jessica; Hickler, Thomas; Jackson, Stephen T.; Kemp, Melissa; Koch, Paul L.; Kremen, Claire; Lindsey, Emily L.; Looy, Cindy; Marshall, Charles; Mendenhall, Chase; Mulch, Andreas; Mychajliw, Alexis M.; Nowak, Carsten; Ramakrishnan, Uma; Schnitzler, Jan; Das Shrestha, Kashish; Solari, Katherine; Stegner, Lynn; Stegner, M. Allison; Stenseth, Nils Chr.; Wake, Marvalee; Zhang, Zhibin
    Conservation of species and ecosystems is increasingly difficult because anthropogenic impacts are pervasive and accelerating. Under this rapid global change, maximizing conservation success requires a paradigm shift from maintaining ecosystems in idealized past states toward facilitating their adaptive and functional capacities, even as species ebb and flow individually. Developing effective strategies under this new paradigm will require deeper understanding of the long-term dynamics that govern ecosystem persistence, and reconciliation of conflicts among approaches to conserving historical versus novel ecosystems. Integrating emerging information from conservation biology, paleobiology, and the Earth sciences is an important step forward on the path to success. Maintaining nature in all its aspects will also entail immediately addressing the overarching threats of growing human population, overconsumption, pollution and climate change.
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    Combined Influence of Soil Moisture and Atmospheric Evaporative Demand Is Important for Accurately Predicting US Maize Yields
    (Springer Science and Business Media LLC, 2020-02-18) Rigden, A. J.; Mueller, N. D.; Holbrook, N. M.; Pillai, Natesh; Huybers, Peter
    Understanding the response of agriculture to heat and moisture stress is essential to adapt food systems under climate change. Although evidence of crop yield loss with extreme temperature is abundant, disentangling the roles of temperature and moisture in determining yield has proven challenging, largely due to the limited soil moisture data and the tight coupling between moisture and temperature at the land surface. Here, using well-resolved observations of soil moisture from the recently launched Soil Moisture Active Passive satellite, we quantified the contribution of imbalances between atmospheric evaporative demand and soil moisture to maize yield damages in the U.S. Midwest. We show that retrospective yield predictions based on the interactions between atmospheric demand and soil moisture significantly outperform those using temperature and precipitation singly or together. The importance of accounting for this water balance is highlighted by the fact that climate simulations uniformly predict increases in atmospheric demand during the growing season but root-zone soils that are variously drier or wetter. A damage estimate conditioned only on simulated changes in atmospheric demand, as opposed to also accounting for changes in soil-moisture, would erroneously indicate approximately twice the damage. This research demonstrates that more accurate predictions of maize yield can be achieved by using soil moisture data and indicates that accurate estimates of how climate change will influence crop yields requires explicitly accounting for variations in water availability.