13 million x 3.6 is 46.8 million. The US labor force, employed and unemployed, is 156 million. We could employ everyone who wants a job and have jobs left over. This does not count the new construction needed to deal with global warming. I read articles about how robots are going to make everyone unemployed. Long term this might be true. But short term we have to rebuild the world. After that is done, we can worry about unemployment.
Some of this is probably high-tech skilled work, but a lot of it is stuff like insulating houses and planting wind breaks. CCC work.
All the pine forests being destroyed by warm winters and pine beetles are going to have to be replaced with trees that are heat and beetle tolerant... That's a lot of CCC work.