What is the purpose of popsicles?

No clue. The heatwave missions give minimal snowflake awards, whole season seems unattainable. I have finished two and can only buy bronze industrial speed up tokens. Just not worth the time until new patch please. 

^ What they just posted.  They are used in the Chicago missions.

Absolutely the worst decision to make popsicle some type of reward but not a reward. It's the major reward in our challenge windows but only serves to support missions. People have full-time jobs, school and families we aren't on enough to enjoy this option.  This was a bad decision.  The old rewards was better. I did 1 mission took 6 hrs got 800 snowflake coins and can't buy a darn thing with them. That's just not worth my time.