You have likely heard or read by now that the first 8 months of global temperature in 2010 were the warmest of any such period in recorded history. Unlike earlier months this year, I’ve started to see more coverage of this in the corporate media. Unfortunately, the coverage I have seen has been short and lacking in critical context. Most of the coverage has actually been of anecdotal situations, like the record-shattering 2010 Russian heat wave. Stories about the above-average Atlantic hurricane season and the Pakistani floods leaving tens of millions displaced have typically not included much, if any, notation that record heat has been recorded across the globe.
NOAA recorded the 3rd warmest August on record; the 2nd warmest Jun-Aug on record; and Jan-Aug 2010 tied the same time period from 1998 as the warmest on record. The most intense El Nino in recorded history occurred in 1997-1998, which helped push global temperatures to record levels. The El Nino of 2009-2010 wasn’t nearly as strong, but added to the background warming brought about by global warming to match the warmest Jan-Aug in modern history.
NASA’s global analysis reported a +0.67°C (+1.206°F) surface temperature anomaly for August 2010 (over the 1951-1980 base period). August 2010 had the 7th highest anomaly of Augusts in the NASA dataset, according to NASA’s GISS dataset.
NOAA’s global analysis reported a +0.6°C (+1.08°F) surface temperature anomaly for August 2010. According to the NOAA methodology, the two warmer Augusts observed were in 1998 (+1.3°F) and 2009 (+0.62°C or +1.12°F).
According to NASA, the Jan-Aug 2010 period has been the warmest on record: +0.67°C (+1.206°F). For comparison, NASA includes the same period from the two all-time warmest years in their dataset so far: 2005 and 1998 (note: the Jan-Aug 1998 and 2005 periods were not the two warmest on record; only the full annual time period was). Globally averaged surface temperatures in Jan-Aug 2005 were +0.60°C (+1.08°F); the same period in 1998 was +0.63°C (+1.134°F). So the Jan-Aug 2010 observed global temperature anomaly was 0.04°C more than the same period in the warmest year to date on record.
According to NOAA, the Jan-Aug 2010 period has tied 2008 as the warmest such period: +0.67°C (+1.206°F). The NOAA site also contains information from the same period during the warmest or the next warmest year on record. Their methodology differs slightly from NASA’s, but is just as valid and acts as an independent check on the other dataset. NOAA’s methodology identified 1997 as the next (2nd) warmest for global land and ocean surface temperatures at +1.04°C (+1.87°F).
One obvious question arising from all of this data is where will 2010 global temperatures rank at the end of the year? While difficult to pin down exactly, I think the moderate-strength La Nina that has developed over the past 4 months will keep sea surface temperatures cool enough over a large enough area to take 2010 out of contention for the warmest year on record. A much weaker La Nina developed even later in 2005, allowing record or near-record monthly anomalies in September and October to push 2005 over 1998 as the warmest year. I do think that 2010 will rank in the top 3 years, however. The second half of 1998 also witnessed a rapid transition from a strong El Nino to a moderate La Nina. These kind of large-scale oscillations have a lot of influence over month-to-month temperature anomalies over large areas. Conditions globally are also similar enough to 2009 and 2007 that, barring a large-scale volcanic eruption, 2010 will rank as one of the warmest years on record, just as global warming science projects as likely to occur.
It is worth noting that the past 12 months were among the warmest 12 consecutive month period in recorded history. No month in that time period had a global temperature anomaly less than +0.5°C. Not one. It’s been over 16 months since the last monthly anomaly was “only” +0.3°C to +0.5°C. As I stated above, a moderate strength La Nina was present during that time. While the current La Nina has developed, global temperature anomalies have so far slipped only +0.67°C. Will this La Nina cause future monthly anomalies to fall back beneath +0.5°C? We’ll have to wait and see.
The larger point is this: even as large-scale cooling patterns periodically emerge, monthly minimum temperature anomalies have risen over time. The same can be said for yearly minimum temperature anomalies. This pattern manifests most clearly when decadal minima/maxima are compared. The coolest year of the 2000′s, 2008, was warmer than all but one year in the 1990′s. The 1990′s present a more challenging comparison, but the overall trend remains valid. With a massive volcanic eruption in 1991, 1992 was the coolest year of the 1990′s; it was also cooler than 7 years of the 1980′s. Taking 1992 & 1993 out of consideration, 1994 was the coolest year of the 1990′s, and was warmer than 5 years of the 1980′s. A similar story emerges moving further back: 1982 was the coolest year of the 1980′s and it was warmer than 6 years of the 1970′s. The pace of global warming is accelerating with time. Will the 2010′s average +0.6°C, or will they be even higher?
Left out of this particular discussion are the growing examples of global warming effects. Massive heat waves, flood and stronger hurricanes have all made the news so far in 2010. Those events will continue to grow in size and intensity. I’ll try and post something about that soon.