First, recent surveys suggest the vast majority of people support our involvement - regardless of political party. So clearly this is just a deranged lunatic trying to support his own financial interests and nothing to do with the reality of the people's will. This will clearly be a major campaign point in the mid-term elections. Article: Majorities of Americans in Every State Support Participation in the Paris Agreement
Second, I've seen multiple pieces suggest that the largest US cities, the most populated states, and the richest companies are all planning on meeting the same regulatory requirements set by the agreement. Article: Climate Mayors commit to adopt, honor and uphold Paris Climate Agreement goals.
To ensure that this is the case, contact your local and state politicians, and continue to minimize your carbon footprint by buying only from those companies that produce sustainable goods. See 25 Ways to Reduce Your Carbon Footprint
One last point. It will take the country four years to complete the withdrawal process. This means that the exit will be finalized after the next presidential election in 2020. Which means, you have plenty of time to campaign for a candidate who will back climate change policy.