Is the ocean warming like the atmosphere...and if so, what problems could that cause?
The answer is yes...and there are several problems. To try to answer this in just a paragraph is to superficially skim the surface of this very important issue. But let's tackle a few of the key points.
The first and most obvious issue is that sea ice is melting; the ice that does form is thinner...and lasts for a shorter period than has typically been the case. Because ice and snow reflect sunlight and darker ocean water absorbs it, that's causing rapid warming in the polar and near polar regions. As sea water warms, it expands and that enhances rising sea levels...and the potential flooding impact from storms approaching coastlines. The warming atmosphere (with higher CO2 levels) also results in some of the CO2 being absorbed by sea water, which changes the pH, or chemistry of sea water-making it more acid. That makes it harder for any form of marine life using a shell as protection to 'build' such shells...and the warming of ocean water also stresses corals...leading to bleaching...or the 'die off' of the coral polyps that populate the reef.