PARENT SESSION
Poster Session #50: Climate Change.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Analysis of 21^st century runoff under elevated CO₂ using the VEMAP II data set.

Gordon, Wendy^*,1, Famiglietti, James², Fowler, Norma¹, ¹ Section of Integrative Biology, Austin, TX² Department of Earth System Science, Irvine, CA

ABSTRACT- In VEMAP II, future climate (1994-2100) simulations were performed using the Canadian Centre for Climate Modeling and Analysis (CGCM1 version) and the Hadley Centre for Climate Prediction and Research of the Meteorological Office of the United Kingdom (HADCM2 version) coupled ocean-atmosphere general circulation models. A key component of VEMAP II was the factorial experimental design in which simulations were run with both climate and CO₂ changing through time, and with solely climate changing through time. We examined projected runoff from four of the terrestrial ecosystem models participating in VEMAP: BIOME-BGC, CENTURY, LPJ, and MC1. Of the four models we examined, all but BIOME-BGC project increases in surface runoff as a result of increasing CO₂. BIOME-BGC is the sole model that consistently projects decreases in surface runoff. The four models vary, however, in the magnitude of their projections of changes in runoff, regardless of whether the projections are for increases or decreases. On average, MC1 predicts little change as a result of increases in CO₂, whereas LPJ projects very large increases in runoff, some of which exceed 300%. However, the magnitude of the increases is smaller under CGCM1 than HadCM2, and the decrease is larger under CGCM1 than HadCM2. The effects on 13 selected watersheds are presented including changes in the magnitude and timing of runoff compared to a baseline period of 1961-1990 and in relation to projected changes in precipitation.

KEY WORDS: terrestrial ecosystem modeling, runoff, climate change, vemap