What is the most effective way to mitigate climate change?

Jayson Lusk discusses this article:

The climate mitigation gap: education and government recommendations miss the most effective individual actions
Seth Wynes1,2,3 and Kimberly A Nicholas1
Published 12 July 2017 • © 2017 IOP Publishing Ltd
Environmental Research Letters, Volume 12, Number 7

One of the top things on the list (#2) was living car free. That reminds me of a post I wrote a couple years back over at Economic Sense: Hybrid Corn vs Hybrid Cars. In that post I noted:

"According to research from PG Economics, in 2009 alone, greenhouse gas reductions associated with biotechnology were equivalent to removing 7.8 million cars from the road."

It would be interesting if we could get data to put this in terms of individual consumer choices. To what extent would changing from an organic GMO free diet to a conventional diet containing GMOs impact our carbon foot print? I'm not sure this is really a practical question, most people probably consume a mix of foods (even Whole Foods shoppers) and on an individual level this may not make a big difference. But there definitely could be an aggregate effect. I have not reviewed the methods in this particular study, but as a conversation piece it brings up a very relevant concern - what would happen if consumer sentiments and the regulatory environment continued to disincentivize the production of genetically engineered foods? (we've seen this with finely textured beef for sure, and rBSt) While other studies might provide different estimates of the effect size of CO2 emissions related to biotech adoption, at least directionally our experience suggests that these technologies make it possible to produce the same or additional levels of output while reducing the toxicity of chemical applications, complementing crop rotation and no till practices that reduce fertilizer runoff and pollution, as well as require less energy moving very heavy equipment across fields (which in turn would reduce CO2 at some level).

In terms of practical policy applications, how much coercion/regulation/taxation/incentivization would be required to convince or force 8 million people to give up their cars? It seems a lot easier for me as a consumer to freely choose to consume a mountain dew with high fructose corn syrup derived from GMO corn than to make a huge change in my lifestyle like going car free. And it seems like a very easy choice for farmers to keep planting biotech.

***UPDATED (July 28, 2017): I just realized there has been an update to this study:

Environmental impacts of genetically modified (GM) crop use 1996–2015: Impacts on pesticide use and carbon emissions
Graham Brookes & Peter Barfoot
GM Crops & Food Vol. 8 , Iss. 2,2017
Link: http://www.tandfonline.com/doi/full/10.1080/21645698.2017.1309490

The updated number of car equivalent levels of CO2 reductions due to area planted to biotech crops is closer to 12 million (11.9).

Reference:

GM crops: global socio-economic and environmental impacts 1996-2009. Brookes and Barfoot.