The problem with global warming is increasingly in the last phases -- when the global warming proponents are confronted with the fact that global temperatures have not increased in the last 10-15 years the way their models predicted, they refuse to admit that their models are flawed and their theory has been "falsified." But the evidence is getting to be overwhelming in the opposite direction:
While Earth’s climate has warmed in the last 33 years, the climb has been irregular. There was little or no warming for the first 19 years of satellite data. Clear net warming did not occur until the El Niño Pacific Ocean “warming event of the century” in late 1997. Since that upward jump, there has been little or no additional warming.
"Part of the upward trend is due to low temperatures early in the satellite record caused by a pair of major volcanic eruptions,” Christy said. “Because those eruptions pull temperatures down in the first part of the record, they tilt the trend upward later in the record.”
Christy and other UAHuntsville scientists have calculated the cooling effect caused by the eruptions of Mexico’s El Chichon volcano in 1982 and the Mt. Pinatubo volcano in the Philippines in 1991. When that cooling is subtracted, the long-term warming effect is reduced to 0.09 C (0.16° F) per decade, well below computer model estimates of how much global warming should have occurred.