It’s been three months since the Summer 2012 snapshot, and it’s time for an updated look at the official scientific data. Does it show the earth breaking new records? Is it breaking them as fast as scientists have predicted?
Oceans and Ice
After several years of stalling, the northern polar cap retreated significantly to a record low in September. It quickly recovered to the previous October lows, but even now it is drifting into new record low territory for this time of the year. Skeptics continue to claim it’s just part of a cycle that’s bigger than our relatively short satellite record of 30+ years, and the ice definitely didn’t disappear this summer as some scientists predicted five years ago, but it’s still hard to ignore a new low that’s hundreds of thousands of square kilometers below the previous record. For the first time I’m going to say that YES the arctic ice cap looks like global warming.
On the other side of the globe, the southern ice cap actually reached a record high this summer. Furthermore, it looks like the levels have been above average for all of 2012. Now, this record high wasn’t nearly as large as the Arctic’s record low, and scientists say this is exactly what we’d expect because southern temperatures are above normal but still below freezing which means more precipitation which means more ice, but, hey, I guess we’ll know if they’re right if it gets even hotter and starts melting. Additionally, reports that the ice is melting underneath still don’t seem to be affecting the surface data at all. So, NO, the antarctic ice cap still doesn’t smell like a warming planet.
Not much movement here since the last update. The data still shows a slow rise of 3.1mm/yr, which does not look at all like an acceleration to put it on pace to meet projections for the end of this century. Once the year is complete I’ll do some more rigorous analysis of changes in annual maximums and averages to get a better picture of what the data is saying. For now I think that NO the oceans are not rising as much as predicted.
US heat. The contiguous United States has allegedly had its warmest January-September by a full 1.3 degrees Fahrenheit over the previous record of 2006. However, Alaska (which is half as big) has had its 18th coolest January-September ever, a full 2.0 degrees below average and more than 4 degrees below its record which still stands from the 1920’s. I will rule this overall as a very slight YES for looking like global warming.
Globally, NOAA says we’re having the 8th warmest year on record so far. This is up from the 11th warmest year pace of three months ago – we allegedly just tied for the warmest September ever – but it still doesn’t look like we’ve had any overall warming this century, much less an acceleration. I continue to rate this one NO.
The Drought Monitor lists 73% of the US in drought, down a bit from three months ago but still very elevated. However, precipitation levels show this is nowhere near unprecedented. This year still looks much wetter than the year of 1988 and all of those severe droughts from the 1920’s and 1930’s. In fact there is a slight long-term trend of increased precipitation, but the years since 2000 actually look less extreme than the preceding decades. I still think the data says NO droughts are not becoming more common.
Thanks largely to this year’s (unexceptional) drought, there have hardly been any tornadoes in the US since the spring, and 2012 may even flirt with the record low for tornadoes in a year. The revised count of 23 strong (EF3+) tornadoes is actually lower than the estimate of 26 given three months ago. Reviewing the long-term graph of strong US tornadoes below, it looks like 2012 will fall safely within that lower average of tornadoes we have seen since the 70’s. There is absolutely NO trend of increasing tornadoes.
Atlantic hurricanes. The 2012 Atlantic hurricane season is mostly over. There have been 10 named hurricanes for the 2nd time in 3 years. This is relatively rare, but there were double-digits in 3 of 4 years in the 90’s followed by only 1 double-digit year in the 00’s. If we have more double-digit years this decade it could signify an increasing trend, but it is too early to tell from just this year, which did not break any quantity records. There was actually only 1 “major” hurricane (Cat 3+) in 2012, which is the lowest number since 1997.
The Northeast is still dealing with the aftermath of Hurricane Sandy, which did come with a couple records, including the largest hurricane ever recorded in the Atlantic and the lowest pressure for a hurricane that far north, among others. However, the 33-year-old record for the largest storm ever still belongs to the Pacific’s Typhoon Tip. Additionally, as Roger Pielke points out, we are also seeing some records in the other direction; it has been seven years since a hurricane of Category 3 or stronger made landfall in the US, which is “the longest such span in over a century.” So far, NO, it doesn’t look like hurricanes are becoming stronger or more frequent.
Overall, I do not see a picture of a warming planet. The sharp melting of the Arctic ice cap is the strongest evidence for it, but it does not seem to be correlating with an acceleration in sea level rise or any noticeable increase in global temperatures. There does seem to be an increase in recorded US temperatures, but it does not seem to be correlating with any increased drought on the one hand or severe weather on the other. Please let me know if you feel my skeptical bias is clouding my interpretation of the data. In three months I will analyze 2012 as a whole compared to recent years as well as how this decade is unfolding compared to earlier ones.