title: Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves.
abstract: Generating credible climate change and extremes projections remains a high-priority challenge, especially since recent observed emissions are above the worst-case scenario. Bias and uncertainty analyses of ensemble simulations from a global earth systems model show increased warming and more intense heat waves combined with greater uncertainty and large regional variability in the 21st century. Global warming trends are statistically validated across ensembles and investigated at regional scales. Observed heat wave intensities in the current decade are larger than worst-case projections. Model projections are relatively insensitive to initial conditions, while uncertainty bounds obtained by comparison with recent observations are wider than ensemble ranges. Increased trends in temperature and heat waves, concurrent with larger uncertainty and variability, suggest greater urgency and complexity of adaptation or mitigation decisions.
authors.affiliation: Geographic Information Science and Technology Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. gangulyar@ornl.gov
authors.forename: Auroop R
authors.initials: AR
authors.lastname: Ganguly
authors.forename: Karsten
authors.initials: K
authors.lastname: Steinhaeuser
authors.forename: David J
authors.initials: DJ
authors.lastname: Erickson
authors.forename: Marcia
authors.initials: M
authors.lastname: Branstetter
authors.forename: Esther S
authors.initials: ES
authors.lastname: Parish
authors.forename: Nagendra
authors.initials: N
authors.lastname: Singh
authors.forename: John B
authors.initials: JB
authors.lastname: Drake
authors.forename: Lawrence
authors.initials: L
authors.lastname: Buja