Two More Papers On the Complexity Of Climate Science

In response to the post

A Research Paper “C4 Grasses Prosper As Carbon Dioxide Eliminates Desiccation In Warmed Semi-Arid Grassland” By Morgan Et Al 2011

I was alerted to the two papers below [thanks to Robert Pollock for alerting us to them!]. These paper provide further documentation on inadequately examined issues in assessing climate science by reports such has have been completed by the IPCC. [highlights added]

Mahowald, N. M. (2007), Anthropocene changes in desert area: Sensitivity to climate model predictions,Geophys. Res. Lett.,34,L18817,  doi:10.1029/2007GL030472.

the abstract reads

Changes in desert area due to humans have important implications from a local, regional to global level. Here I focus on the latter in order to better understand estimated changes in desert dust aerosols and the associated iron deposition into oceans. Using 17 model simulations from the World Climate Research Programme’s Coupled Model Intercomparison Project phase 3 multi-model dataset and the BIOME4 equilibrium vegetation model, I estimate changes in desert dust source areas due to climate change and carbon dioxide fertilization. If I assume no carbon dioxide fertilization, the mean of the model predictions is that desert areas expand from the 1880s to the 2080s, due to increased aridity. If I allow for carbon dioxide fertilization, the desert areas become smaller. Thus better understanding carbon dioxide fertilization is important for predicting desert response to climate. There is substantial spread in the model simulation predictions for regional and global averages.

Zavaleta, E. et al, 2003: Plants reverse warming effect on ecosystem water balance. PNAS.

The abstract reads

Models predict that global warming may increase aridity in water-limited ecosystems by accelerating evapotranspiration. We show that interactions between warming and the dominant biota in a grassland ecosystem produced the reverse effect. In a 2-year field experiment, simulated warming increased spring soil moisture by 5–10% under both ambient and elevated CO₂. Warming also accelerated the decline of canopy greenness (normalized difference vegetation index) each spring by 11–17% by inducing earlier plant senescence. Lower transpirational water losses resulting from this earlier senescence provide a mechanism for the unexpected rise in soil moisture. Our findings illustrate the potential for organism–environment interactions to modify the direction as well as the magnitude of global change effects on ecosystem functioning.

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