The EU committed to net zero green house emissions by 2050. (Source)
It is regularly said that the a carbon tax of USD 40-80 / t CO2e (USD 50-100 by 2030) would be sufficient to reach the Paris commitment for 2030, a 40% reduction vs 1990. (Source)
Presumably the price of carbon emissions would need to increase exponentially after 2030 since the low hanging fruits will have been picked by then. Some demand could be discouraged through direct regulation but there may be a residual carbon intensity in the economy that would need fairly high emissions prices before considering substitutes.