Planet Day, Wednesday 5th April 2017

The event will take place at the University of Toronto, Scarborough campus (Room AA160, Arts & Administrative building - see map). It will consist of three talks by Prof. Dorian Abbot from the University of Chicago, Prof. Eliza Kempton from Grinnell College and Prof. Richard Peltier from the Department of Physics at UofT. Coffee and tea will be provided throughout the day’s events, with a Wine and Cheese social to follow the final talk. Transportation will be provided between the St. George and Scarborough Campuses, at multiple times during the day. Note that an extra mid-afternoon trip from UTSC to St. George has been added (see details below).

Talks

• Eliza Kempton, Grinnell College
  Revealing the Atmospheres of Extrasolar Super-Earths
  Abstract:
  

  Discoveries of extrasolar planets over the last two decades have reshaped our understanding of how planetary systems form. Super-Earths – planets intermediate in size/mass between Earth and Neptune – do not exist in our Solar System, and the discovery of such planets poses a challenge to theories of planetary formation and composition based on the Solar System paradigm. Through observations of the atmospheres of these planets, we can learn about their formation history, their climate, and in some cases their propensity to support life. This talk will focus on the modeling of super-Earth atmospheres as it relates to current and future observations. I will detail the current state of characterization efforts for super-Earth atmospheres, focusing on the challenges and successes in modeling and interpreting the early observations of these objects. I will conclude with a forward-looking view of super-Earth atmospheric studies over the next 5-10 years, in the era of JWST and 30-meter class ground-based telescopes.



• Richard Peltier, University of Toronto
  A stringent test of coupled climate system interactions: the Dansgaard-Oeschger Oscillation
  Abstract:
  

  Under cold glacial conditions, oxygen isotopic variability from Summit Greenland ice cores suggests the climate system to have been dominated by a mode of variability that consisted of individual pulses of relaxation oscillation form. This intense mode of variability has only recently been recovered by direct numerical simulation of the coupled atmosphere-ocean-sea ice system. The underlying physics is thereby shown to involve a "kicked" salt oscillator operating in the Atlantic Basin in which the kick that induces the oscillatory behavior is associated with a recurrent instability of continental ice cover. These so-called Heinrich instability events involved the collapse of the Hudson Strait ice stream that connected the core of the Laurentide ice sheet to the Atlantic Ocean.



• Dorian Abbot, University of Chicago
  The Snowball Bifurcation on Exoplanets
  Abstract:
  

  The Snowball Earth episodes may have affected the development of life on Earth through increasing atmospheric oxygen and spurring evolution. Considering the habitability and increase in complexity of life on other planets therefore requires thought about Snowball climate states. Using an energy balance model and global climate model, I will show that it is unlikely a tidally locked planet could experience a Snowball Earth bifurcation. Instead the planet would smoothly transition to global ice coverage. This is due to the difference in the shape of the insolation, which increases strongly toward the substellar point on a tidally locked planet. I will then change focus slightly and explain how climate oscillations between a warm state and a Snowball state can occur on a planet within the habitable zone that has a small CO2 outgassing rate. I will develop analytical relations to understand these cycles and outline scalings in variables such as the cycle period as a function of important climatic and weathering parameters. Work of this type should help us understand the context of planetary habitability and focus on appropriate targets as we seek to find the first inhabited exoplanet.

Schedule

• 9:15am: Bus leaves from St. George (from corner of Huron and Russell Street)
• 10:00am: Coffee, Tea, and Cookies
• 10:30am: First Speaker: [ E. Kempton ]
• 12:00pm: Second bus from St. George departs for UTSC
• 12:00-1:30pm: Lunch
• 1:00pm: First bus departs UTSC for St. George
• 1:30pm: Second speaker [ R. Peltier ]
• 2:30pm: Second bus departs UTSC for St. George (extra bus ride)
• 3:00pm: Coffee, Tea and Cookie break
• 3:30pm: Third speaker: [ D. Abbot ]
• 5:00pm: Wine and Cheese social
• 6:00pm: Final bus departs UTSC for St. George