The atmospheric chemistry brown bag talk series at the University of Maryland, College Park, continues this Friday February 8 at 12:00 PM when Professor Yongyu Hu of Peking University will give a talk entitled:
Hothouse and Dry Climate during the Snowball Earth Aftermath
Carbonates capping Neoproterozoic glacial deposits suggest that the
Snowball Earth was melted by extremely high levels of CO2.
Such high levels of CO2 in the atmosphere could be accumulated due to
volcanic eruptions over time scales of millions of years when weathering
reactions were ceased because of the complete coverage of snow and ice.
Previous simulations have showed that higher than 0.2 bars of CO2 is
required to melt the hard Snowball Earth. It suggests that there must be
supergreenhouse effect during the aftermath of the hard Snowball Earth,
considering high-level CO2 and large amount of water vapor in the atmosphere.
To test how high surface temperature could be, we performed GCM
simulations with various levels of CO2. It is found that global-mean
surface air temperatures is about 60?C for 0.2 bars of CO2, and the
highest surface temperature over continents can be as high as 80?C.
Associated with the hothouse climate, water evaporation cools the
ocean surface and causes strong boundary inversion, which suppresses
convection and thus precipitation, and leads to extremely dry climate
(atmospheric relative humidity can be as low as 20%).
Atmospheric circulations under such the hothouse climate conditions are very
different from that of the present-day. How life in the Neoproterozoic era
survived from the hothouse climate (not only extremely cold climate in the
Snowball Earth episodes) remains an intriguing but unanswered question.
Note: Talks are informal and usually 40-50 minutes in length.
When: 12:00 PM Friday unless noted above Where: Department’s
library (3400 Computer and Space Science Building)
Parking is available in the (Football) Stadium Garage. Please park in
a numbered spot and pay at the parking machine located near the garage’s