Climate Dynamics Group
at the University of California, Santa Cruz

Poleward moisture transport into the Arctic occurs via short-lived, episodic intrusions of warm, moist air masses. These extreme transport events are associated with an enhanced greenhouse effect that is expected to slow sea-ice growth in winter and hasten the start of spring melt season. Yet, their impact on the Arctic energy balance averaged over longer time scales has been difficult to quantify, in part due to the challenge in separating local and remote Arctic moisture sources. We implement numerical water tracers and source-aware radiative locking in an Earth system model to reveal how moist intrusions and their vertical structure sustain water vapor and cloud feedbacks over the Arctic and thereby elicit sea ice retreat and its attendant feedbacks. This research is supported by the Department of Energy under Award DE-SC0023070.

A random sample of the projects from this collective includes:

• Quantifying moisture sources of Arctic atmospheric rivers during the recent historical period

Since the 1970s, simulations of climate change forced by increased CO₂ concentrations have predicted warming that is greatest in polar regions. This polar-amplified warming has been variously attributed to the ice-albedo feedback, associated with the retreat of reflective sea ice in summer; the lapse rate feedback, associated with vertically nonuniform atmospheric warming in winter; and changes in energy transport by atmospheric circulations. Uncertainty in projections of Arctic climate change arise in part from incomplete understanding of the interconnected nature of these processes, which we strive to disentangle through creative modeling experiments and novel statistical techniques. This research is supported by the National Science Foundation under Award 1753034.

A random sample of the projects from this collective includes:

• Mid-latitude clouds contribute to Arctic amplification via interactions with other climate feedbacks
• Robust polar amplification in ice-free climates relies on ocean heat transport and cloud radiative effects
• Causes of the Arctic's lower-tropospheric warming structure
• Sea ice and atmospheric circulation shape the high-latitude lapse rate feedback
• Warm Arctic-Cold Eurasia pattern driven by atmospheric blocking in models and observations

Feedbacks interact with one another and with the dynamical components of the atmosphere and ocean. By characterizing the local energy balance of the atmosphere, they also enable a diagnostic decomposition of poleward atmospheric energy transport changes into contributions from individual feedbacks, radiative forcing, and ocean heat uptake, which we develop in this research. Such energy transport changes manifest in the changing atmospheric circulations, influencing the magnitude and structure of the tropical Hadley circulation, the Intertropical Convergence Zone, and the midlatitude storm tracks, which are fundamental controls on regional climate and the hydrological cycle.

A random sample of the projects from this collective includes:

• Atmospheric eddies mediate lapse rate feedback and Arctic amplification
• Coupled high-latitude climate feedbacks and their impact on atmospheric heat transport
• Changes in poleward atmospheric energy transport over a wide range of climates: Energetic and diffusive perspectives and a priori theories
• Characterizing the Hadley circulation response through regional climate feedbacks

Uncertainty in the magnitude and geographic pattern of climate change is dominated by divergent predictions among climate models. Model differences are closely linked to their representation of climate feedbacks, that is, the amplifying or stabilizing radiative fluxes that are caused by changes in clouds, water vapor, surface albedo, and other factors, in response to an external climate forcing. Progress in constraining this uncertainty is therefore predicated on understanding how individual climate feedbacks aggregate into a regional and global climate response.

A random sample of the projects from this collective includes:

• The nonlinear and nonlocal nature of climate feedbacks
• Aquaplanet radiative kernels
• The remote impacts of climate feedbacks on regional climate predictability
• The influence of climate feedbacks on regional hydrological changes under global warming
• The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake

Serious Games for Climate Change is a research cluster at the nexus of game design, climate science, and learning science. In collaboration with Elizabeth Swensen (Department of Performance, Play & Design), we create games that foster scientific thinking and promote the learning of complex topics through experimentation and narrative. Games additionally hold promise as tools for social empowerment, inspiring agency to advance climate solutions.

A random sample of the projects from this collective includes:

• Warmer