How much does Bitcoin's energy usage correlate with increased traffic?

Can't find any info on what the potential cost would be if Bitcoin was to be used on a global scale on a far greater magnitude as it is being currently.

Would the difficulty of mining automatically be adjusted such that it discourages situations where it may be extensively used and utilises very large amounts of the global energy? Let's say a potential scenario like 10% of the world's energy output under heavy usage.

Thinking long term here.