That'd be all well in good if this were the first time it's ever happened. The old record for that city in OK was -25F back in 1930, and the state's record low was -27F in 1905, 1930, and 1947. The new record, -28F according to the below link, is obviously a bit colder but not far off from the records.
Topeka, Kansas broke a record too - 9F, but they were -8F back in 1982.
I don't see how bad weather for a year or two leads to "impossible not to believe in climate change." Keep in mind that there's also better recording devices nowadays, so who knows if it was really -27F in 1905 or if it was -29F. Hard to tell.
http://www.gtrnews.com/greater-tulsa-reporter/9389/oklahoma-colder-than-the-south-pole-this-morning