From Skeptical Science by John Cook. Read it all here.
Over the past 40 years, global ocean heat content has shown a long term warming trend. However, the warming hasn’t been monotonic. There are periods where ocean heat drops for several years before the warming trend resumes. On several occasions, this is due to large volcanic eruptions which cause a drop in global temperatures. On other occasions, upper ocean heat drops with no volcanic activity. What causes these breaks in warming?
Read it all here.