M. G. De Kauwe

Land surface models systematically overestimate the intensity, duration and magnitude of seasonal-scale evaporative droughts

Land surfacemodels (LSMs)must accurately simulate observed energy andwater fluxes during droughts in order to provide reliable estimates of futurewater resources.We evaluated 8 different LSMs (14model versions) for simulating evapotranspiration (ET) during periods of evaporative drought (Edrought) across sixflux tower sites. Using an empirically defined Edrought threshold (a decline in ET below the observed 15th percentile), we show that LSMs simulated 58 Edrought days per year, on average, across the six sites,∼3 times asmany as the observed 20 d. The simulated Edrought magnitudewas∼8 times greater than observed and twice as intense. Ourfindings point to systematic biases across LSMswhen simulating water and energy fluxes underwater-stressed conditions. The overestimation of key Edrought characteristics undermines our confidence in themodels’ capability in simulating realistic drought responses to climate change and haswider implications for phenomena sensitive to soilmoisture, including heat waves.

Comment on "Mycorrhizal association as a primary control of the CO2 fertilization effect"

Terrer et al. (Reports, 1 July 2016, p. 72) used meta-analysis of carbon dioxide (CO2) enrichment experiments as evidence of an interaction between mycorrhizal symbiosis and soil nitrogen availability. We challenge their database and biomass as the response metric and, hence, their recommendation that incorporation of mycorrhizae in models will improve predictions of terrestrial ecosystem responses to increasing atmospheric CO2.

Evaluating CMIP5 Model Agreement for Multiple Drought Metrics

AbstractGlobal climate models play an important role in quantifying past and projecting future changes in drought. Previous studies have pointed to shortcomings in these models for simulating droug...

Comment on “Mycorrhizal association as a primary control of the CO2 fertilization effect" (technical comment)

Terrer et al. (Reports, 1 July 2016, p. 72) used meta-analysis of carbon dioxide (CO2) enrichment experiments as evidence of an interaction between mycorrhizal symbiosis and soil nitrogen availability. We challenge their database and biomass as the response metric and, hence, their recommendation that incorporation of mycorrhizae in models will improve predictions of terrestrial ecosystem responses to increasing atmospheric CO2.

Mycorrhizal association as a primary control of the CO2 fertilization effect (technical comment)

Terrer et al. (Reports, 1 July 2016, p. 72) used meta-analysis of carbon dioxide (CO2) enrichment experiments as evidence of an interaction between mycorrhizal symbiosis and soil nitrogen availability. We challenge their database and biomass as the response metric and, hence, their recommendation that incorporation of mycorrhizae in models will improve predictions of terrestrial ecosystem responses to increasing atmospheric CO2.