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in creator/contributor: "Lobell, D"

open access

Empirical evidence for a recent slowdown in irrigation-induced cooling

Understanding the influence of past land use changes on climate is needed to improve regional projections of future climate change and inform debates about the tradeoffs associated with land use decisions. The effects of rapid expansion of irrigated area in the 20th century has remained unclear relative to other land use changes, such as urbanization, that affected a similar total land area. Using spatial and temporal variations in temperature and irrigation extent observed in California, we sh… more

Date: January 19, 2007

Creator: Bonfils, C & Lobell, D

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Global crop yield losses from recent warming

Global yields of the world-s six most widely grown crops--wheat, rice, maize, soybeans, barley, sorghum--have increased since 1961. Year-to-year variations in growing season minimum temperature, maximum temperature, and precipitation explain 30% or more of the variations in yield. Since 1991, climate trends have significantly decreased yield trends in all crops but rice, leading to foregone production since 1981 of about 12 million tons per year of wheat or maize, representing an annual economi… more

Date: June 2, 2006

Creator: Lobell, D & Field, C

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comment on "Methodology and results of calculating Central California surface temperature trends: evidence of human-induced climate change?" by Christy et al. (2006)

Understanding the causes of observed regional temperature trends is essential to projecting the human influences on climate, and the societal impacts of these influences. In their recent study, Christy et al. (2006, hereinafter CRNG06) hypothesized that the presence of irrigated soils is responsible for rapid warming of summer nights occurring in California's Central Valley over the last century (1910-2003), an assumption that rules out any significant effect due to increased greenhouse gases, … more

Date: March 28, 2006

Creator: Bonfils, C; Duffy, P & Lobell, D

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Climate change uncertainty for daily minimum and maximum temperatures: a model inter-comparison

Several impacts of climate change may depend more on changes in mean daily minimum (T{sub min}) or maximum (T{sub max}) temperatures than daily averages. To evaluate uncertainties in these variables, we compared projections of T{sub min} and T{sub max} changes by 2046-2065 for 12 climate models under an A2 emission scenario. Average modeled changes in T{sub max} were slightly lower in most locations than T{sub min}, consistent with historical trends exhibiting a reduction in diurnal temperature… more

Date: November 9, 2006

Creator: Lobell, D; Bonfils, C & Duffy, P

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Interpretation of Recent Temperature Trends in California

Regional-scale climate change and associated societal impacts result from large-scale (e.g. well-mixed greenhouse gases) and more local (e.g. land-use change) 'forcing' (perturbing) agents. It is essential to understand these forcings and climate responses to them, in order to predict future climate and societal impacts. California is a fine example of the complex effects of multiple climate forcings. The State's natural climate is diverse, highly variable, and strongly influenced by ENSO. Huma… more

Date: September 21, 2007

Creator: Duffy, P B; Bonfils, C & Lobell, D

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Potential bias of model projected greenhouse warming in irrigated regions

Atmospheric general circulation models (GCMs) used to project climate responses to increased CO{sub 2} generally omit irrigation of agricultural land. Using the NCAR CAM3 GCM coupled to a slab-ocean model, we find that inclusion of an extreme irrigation scenario has a small effect on the simulated temperature and precipitation response to doubled CO{sub 2} in most regions, but reduced warming by as much as 1 C in some agricultural regions, such as Europe and India. This interaction between CO{s… more

Date: April 27, 2006

Creator: Lobell, D.; Bala, G.; Bonfils, C. & Duffy, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Impacts of Future Climate Change on California Perennial Crop Yields: Model Projections with Climate and Crop Uncertainties

Most research on the agricultural impacts of climate change has focused on the major annual crops, yet perennial cropping systems are less adaptable and thus potentially more susceptible to damage. Improved assessments of yield responses to future climate are needed to prioritize adaptation strategies in the many regions where perennial crops are economically and culturally important. These impact assessments, in turn, must rely on climate and crop models that contain often poorly defined uncer… more

Date: January 10, 2006

Creator: Lobell, D; Field, C; Cahill, K & Bonfils, C

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Weather-based forecasts of California crop yields

Crop yield forecasts provide useful information to a range of users. Yields for several crops in California are currently forecast based on field surveys and farmer interviews, while for many crops official forecasts do not exist. As broad-scale crop yields are largely dependent on weather, measurements from existing meteorological stations have the potential to provide a reliable, timely, and cost-effective means to anticipate crop yields. We developed weather-based models of state-wide yields… more

Date: September 26, 2005

Creator: Lobell, D B; Cahill, K N & Field, C B

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Identification of saline soils with multi-year remote sensing of crop yields

Soil salinity is an important constraint to agricultural sustainability, but accurate information on its variation across agricultural regions or its impact on regional crop productivity remains sparse. We evaluated the relationships between remotely sensed wheat yields and salinity in an irrigation district in the Colorado River Delta Region. The goals of this study were to (1) document the relative importance of salinity as a constraint to regional wheat production and (2) develop techniques … more

Date: October 17, 2006

Creator: Lobell, D; Ortiz-Monasterio, I; Gurrola, F C & Valenzuela, L

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atmospheric Climate Model Experiments Performed at Multiple Horizontal Resolutions

This report documents salient features of version 3.3 of the Community Atmosphere Model (CAM3.3) and of three climate simulations in which the resolution of its latitude-longitude grid was systematically increased. For all these simulations of global atmospheric climate during the period 1980-1999, observed monthly ocean surface temperatures and sea ice extents were prescribed according to standard Atmospheric Model Intercomparison Project (AMIP) values. These CAM3.3 resolution experiments serv… more

Date: December 21, 2007

Creator: Phillips, T.; Bala, G.; Gleckler, P.; Lobell, D.; Mirin, A.; Maxwell, R. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Identification of external influences on temperatures in California

We use eight different observational datasets to estimate California-average temperature trends over 1950-1999. Observed results are compared to trends from a suite of control simulations of natural internal climate variability. Observed increases in annual-mean surface temperature are distinguishable from climate noise in some but not all observational datasets. The most robust results are large positive trends in mean and maximum daily temperatures in late winter/early spring, as well as incr… more

Date: June 1, 2006

Creator: Bonfils, C; Duffy, P; Santer, B; Wigley, T; Lobell, D; Phillips, T et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Combined Climate and Carbon-Cycle Effects of Large-Scale Deforestation

The prevention of deforestation and promotion of afforestation have often been cited as strategies to slow global warming. Deforestation releases CO{sub 2} to the atmosphere, which exerts a warming influence on Earth's climate. However, biophysical effects of deforestation, which include changes in land surface albedo, evapotranspiration, and cloud cover also affect climate. Here we present results from several large-scale deforestation experiments performed with a three-dimensional coupled glo… more

Date: October 17, 2006

Creator: Bala, G.; Caldeira, K.; Wickett, M.; Phillips, T. J.; Lobell, D. B.; Delire, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department