Death Valley now crowned 'hottest place on Earth'

It was 90 years ago Thursday that a station in the middle of the Libyan Desert recorded an amazing 58 degree Celsius temperature, which is 136.4 degrees Fahrenheit. That temperature has long stood as the all-time world record for hottest temperature ever recorded.

But not anymore. Now, a 1913 observation from Death Valley holds the record.

On this 90th anniversary of the Libyan record, the World Meteorological Organization stripped El Aziza of the record after a two-year investigation, citing five troubling aspects about the measurement including a potential problem with the thermometers, and a new, inexperienced observer. The 136 degree reading didn't really match well to surrounding readings taken at the time, didn't match current weather conditions, and also didn't match subsequent observations. In other words, the reading came out of left field.

The record has always faced suspicion in the weather community over the years -- in the 90 years since that record, no Earthly temperature has even come close. But in 2010, Christopher Burt, who writes a weather blog for Weather Underground took it upon himself to delve into the record to see if it could be proven for good, one way or the other.

He got in contact with the director of the climate department in Libya, who was eager to help and provided much data to Burt, including the original records of the observation -- something that had not been seen before.

Burt's blog details how the investigation proceeded, including a several month pause during Libya's recent revolution where the Libyan's climate director lost contact with the outside world and there was great fear for the climate director's life. (It's a very dramatic story and worth the read.) But the man recently resurfaced safe and the investigation was allowed to continue.

Among the "smoking guns" of the investigation was a note that a new, inexperienced observer was put in charge just two days before the 58 degree temperature was recorded. Also of note on that day, the temperature readings were about 7 degrees (C) warmer than surrounding stations. Thermometers at the time used a peg that sat on top of the mercury and would remain there at the day's highest spot, recording the high temperature. Burt says the peg was roughly the height of 7 degrees on the thermometer scale so it is possible the observer erroneously read the top of the peg as the day's high instead of the bottom.

That plus the mounting evidence that the temperature was so anomalous compared to surrounding data caused the WMO to officially declare the record invalid.

So who has the record now? It's back in the United States. The official record-holder now belongs to Death Valley in California, which measured a 134 degree temperature on July 10, 1913, although Burt says he's not so sure *that* record is completely accurate either. In a subsequent blog post, Burt says Death Valley observers had a few others in the 130s that month, but Death Valley has never been above 130 since.

Burt thinks a 129 degree reading in Death Valley in 2007 might be the hottest global temperature recorded under modern and very reliable instrument conditions.

What could someday be the hottest place on Earth? Perhaps the Lut Desert in Iran. There are no observation stations there but some infrared satellite images have suggested ground temperatures that have reached around 70 degrees C -- or 158 degrees F!