A Toronto blogger's number-crunching skills turned up an error in the math NASA used to determine historic temperatures, forcing the agency to own up to an embarrassing mistake.

NASA had said 1998 was the hottest year on record in the U.S. but later revised the statistics, issuing a new list that instead named 1934 as the hottest year on the books.

Toronto-based blogger Steve McIntyre found the error. In a tongue-in-cheek posting on his blog climateaudit.org, he compared the race for the top spot to the leaderboard results from the U.S. Open.

"There has been some turmoil yesterday on the leaderboard of the U.S. (Temperature) Open and there is a new leader," he wrote on Aug. 8.

"Four of the top 10 are now from the 1930s: 1934, 1931, 1938 and 1939, while only 3 of the top 10 are from the last 10 years (1998, 2006, 1999). Several years (2000, 2002, 2003, 2004) fell well down the leaderboard, behind even 1900.

McIntyre scrutinized NASA's numbers, looking closely at data that recorded how warm a place is at a specific time, compared to its 30-year average.

He found that the numbers for 1999 to 2000 seemed abnormally high, and discovered that after 1999, the data wasn't being adjusted to figure in the times of day the readings were taken or the locations where they were taken.

He forwarded his findings to NASA, and the review was ordered. Eventually, NASA released a new list of the hottest years on record.

In addition to naming a new year as the hottest, NASA also reduced the mean U.S. temperature anomalies by .15 C for the years 2000 to 2006.

Some consider the adjustment a blow to Al Gore and others who maintain the planet is heating up as the result of global warming. But NASA has downplayed the corrections and even McIntyre has suggested the new numbers would have little impact on climate policy.

McIntyre has said he had fun discovering the flaws, but called the adjustment a "micro-change."

Those who doubt the science behind climate change theory, however, have used the new information as ammunition.

Conservative U.S. radio host Rush Limbaugh called it evidence that global warming is a man-made phenomenon that has been artificially trumped up by liberal scientists.

Others say that proof of errors within the system NASA uses to determine accurate temperature data, means the global warming camp has suffered a significant blow.

The 59-year-old McIntyre is a former mining executive. In 2003 he released data that called into question the accuracy of the "hockey stick" graph used to show rising global temperatures.