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REPORT

Climatic Controls on Continental Erosion

and Sediment Transport (CLAST2019)

4–10 August 2019 | Juneau, Alaska, USA

CONVENERS earth-surface processes and solid Earth datasets across time
Tara N. Jonell, The University of Queensland, School of Earth scales; (6) moving forward: innovations in data sharing, visual-
and Environmental Sciences, St. Lucia, Australia, t.jonell@ ization, and modelling to understand landscapes and climate;
uq.edu.au and (7) history matters: reconciling tectonic, climate, and
Peter D. Clift, Louisiana State University, Dept. of Geology and erosion histories.
Geophysics, Baton Rouge, Louisiana, USA, pclift@lsu.edu
Jan H. Blöthe, University of Bonn, Dept. of Geography, Bonn, PRESENTATIONS AND DISCUSSION
Germany, jan.bloethe@uni-bonn.de The major aims of the talks and focused group discussions
were to (1) identify new and persistent knowledge gaps within
INTRODUCTION AND CONFERENCE DETAILS our communities; (2) define major challenges in addressing these
Although tectonic forces are known to be a strong primary con- gaps; and (3) initiate conversations on the resources needed both
trol on the generation of sediment, this conference assessed the within, between, and outside of our communities to effectively
dynamic role of global and regional climate in controlling the address these over the next five to ten years. Over the course of
production, transport, and deposition of sediments over millennial the week, participants identified three key areas:
to million-year time scales. However, study of climate and earth-
surface process relationships is fundamentally problematic Weather Erodes, Not Climate
because many of these processes act both independently of and as Understanding the relative importance of event-scale and
a consequence of tectonic forcing. This conference sought to dis- extreme events in controlling the sedimentary record has come to
cuss how climatic forcing is translated to the sedimentary record the forefront of several communities. What is the relative impor-
and under what conditions the respective erosional signals can be tance of extreme events over steady-state erosion processes? Are
observed and interpreted unambiguously in terms of paleoenvi- extreme events (mass-wasting, cyclones, wildfires, earthquakes,
ronmental and paleoclimatic change. This transdisciplinary meet- [flash-]floods) controlling the sedimentary record, or are these
ing brought together researchers across a number of sub-fields to events the “noise”? At what scales are events detectable and at
showcase the current state of research, demonstrate contemporary what scales do they matter?
evidence and methods from studies worldwide, and summarize the To understand the immediate and lasting effects of seasonality
research concerns remaining in our communities. and variability, efforts need to be made in not only obtaining mea-
Hosted in Juneau, Alaska, USA, from 4–10 August 2019, surements of totals but also in constraining rates and durations.
CLAST2019 brought together 49 scientists from Australia, Brazil, This includes identifying records for environmental boundary
Canada, France, Germany, Hong Kong, Israel, Italy, Switzerland, conditions in the rock record (elevation, temperature, precipita-
the U.K., and the U.S. The conference kicked off with an ice- tion, wind speed, aridity, and seasonality) and improving our abil-
breaker, was punctuated by a mid-week field trip and sunset din- ity to measure them using novel (bio)geochemical markers, such
ner on Eagle Beach delta, and ended in Tracy Arm Fjord in the as clumped isotopes.
post-meeting field trip. Women scientists accounted for 46% of
participants, and 23 of the participants were early career research- Scale Matters, So Mind the Gap
ers (student and untenured researchers). Early career researchers The issue of comparing observations at varying temporal
presented one third of invited talks. Formalized one-on-one and and spatial scales was identified as a key challenge. We have
informal peer mentoring was achieved throughout the week disparate proxies relevant at different spatiotemporal scales
among researchers and across the wide range of disciplines. and are especially data limited at time scales that might matter.
Presentations were grouped into seven broad climate-erosion Improvement in geochronological techniques has in part
themes: (1) from source to sink: tracing erosional signals; addressed this data gap, but continued effort is needed. Future
(2) beyond the mainstream: continental deposition and erosion approaches looking to quantify transience or disequilibrium will
outside fluvial systems; (3) cycles, thresholds, and feedbacks: need to allow for a holistic interpretation of disparate proxies
the evolving atmosphere and biosphere; (4) from ice to the ocean; and include development of proxies that are truly compatible
(5) closing the gap: emergent tools and techniques for integrating with the scale of observation.

38 GSA Today | June 2020