Time estimation in projects

I'm a data scientist in a technology consultancy. We get asked to put time estimates on projects. The clients are charged based on those estimates. This creates a vulnerability in the business, because data science is an experimental process with uncertainty. It''s not a routine, predictable job that fits into cute time boxes. So those time estimates almost always go wrong.

There must be a better system than this? What is everyone else doing?

business consultancy data data science datascience data scientist experimental job process projects science technology uncertainty vulnerability