You're not the first to put forth this misinterpretation as accurate. It's not. 1998 was the warmest year in the observational record (going back to about 1880 or so) because it was an big El Nino year added to the warming trend that began in the mid-1980s. Examining the full record shows that all El Nino years are warm years (there are good meteorological reasons for that). Several not-quite-as-warm years have followed 1998. Last year was just barely under the 1998 record (some analyses put 2005 ahead of 1998) -- and there was no El Nino. Unless there are really unusual circumstances, the next El Nino year will exceed the 1998 record. This year could actually exceed the 1998 record without an El Nino, and then where will you be?
Warming and cooling of the climate is a natural occurance, we have ice ages, then we warm up. This is caused by the out of balance spinning of the earth and the orbit around the sun, which is also not stable. Everything else is just BS.