There has been considerable debate in Canada on the relative contributions of mercury from natural sources versus releases to the environment from human activity. One of the challenges with this debate is the lack of accurate information on mercury emissions, past and present. Scientists have ana- lyzed sediment cores and determined that the levels of mercury in the environment today are more than double what they were in pre-industrial times. They have also measured mercury in the atmos- phere and found that it continues to increase globally at more than one per cent per year. Total global mercury emissions are estimated to be 5,000 tonnes per.
