It is possible to combine keeping elephants in circuses with decent elephant welfare?
No, it simply isn't. Summarized the reasons are:
Elephants in circuses are confined and chained for literally hours on end
Through physical punishment and the threat of its use, elephants in circuses are trained to pose in unnatural, difficult and partly painful positions
Elephants in circuses are moved, in unbearable heat and below freezing temperatures, from city to city chained in flatbed trucks and in boxcars
The recruitment of elephants to circuses mostly happens through separating calves from their mothers at an early age followed by gruesome disciplining and abusive training
Elephants in circuses are removed from companions to be bought and sold, and frequently moved about
Circus elephants have no level of autonomy over their lives, to the extent where they are trained to defecate into a bucket on command
Circus elephants often have to eat, sleep and defecate in their cage