Full edition for scientific use. Our research aims to measure polarization in public opinion, combining two state-of-the-art approaches in measuring opinion - survey research and big data analytics of social media. We focus on the topic of polarization of opinions on COVID-19 and climate change and identify if and how polarization - a shift towards more extreme positions - occurs within both sources, if and how opinions and respondents differ between sources, and whether the opinions in the two sources are aligned.