Seminar

It has long been hypothesised that global climate may be controlled over long time periods, spanning millions of years, as a result of the role that chemical weathering of silicate minerals plays in removing CO2 from the atmosphere. The uplift and weathering hypothesis related to the growth of the Himalayas and Tibet was for many years considered as the cause of long-term cooling during the Cenozoic. Scientific drilling around the Asian marginal seas now suggests that this mechanism is ineffective in causing large-scale carbon sequestration and similarly, that the burial of organic carbon is unlikely to be significant in removing CO2 in this region. New data collected from around New Guinea, however, raises the possibility that this region may instead be important. Other controlling factors include the slowing of seafloor, spreading during the Neogene, as well as increased subduction of both organic and inorganic carbon into the global subduction system. On shorter timescales, flooding and exposure of wide continental shells in low latitude areas appears to be significant in amplifying climate signals as a result of enhanced chemical weathering, and the growth of forests in low latitudes during sea level, low stands. Plans are now underway to conduct scientific drilling across the Sunda Shelf, the world’s largest low latitude continental shelf to test this hypothesis.