I see what you're saying. You're reading it as "every day is hotter than the previous day". The way I said it is open to misinterpretation but the article is better. It says "record-breaking year of heat" and "broken temperature records every single day over the past year," the record being the highest sea temperature for that day. Every day is an all time high for that day. The oceans are seasonally affected, so not constant temperature even averaged across the globe.
