This web page was prepared as a counterpoint to a report from Environment NH, one of 50 state organsizations started by http://www.fundforthepublicinterest.org/ . I'm pleased with how well it fits, but the interesting thing may be the organization behind the report. In short, Environment New Hampshire appears to have a staff of one parttime person, the report was contracted out by a branch of an umbrella organization and has no NH-specific content other than the logo on the cover and the copyright notice.

We're part way into the year, and several news stories report either that 2010 is going to be the hottest year ever, or the last 12 months is the hottest year ever. Is this premature? Is it significant? That's something not covered by the stories. Let's take a closer look.

In 2008 and 2009 when La Niña was bringing in temperature similar to cool years in the 1970s, that was dismissed as just weather and that you need decades of data to show climate change. Here we are, just a year or too later and part of a year is appears to be good enough to sound the alarm about climate change again.

Climate Cycles

It's a familiar pattern. Personally, given the durations of various events, there are good reasons to look at time periods that are multiples of the cycle or very short parts of the cycle. That's done to suppress their effects on projections of future conditions. Some of these cycles and their periods are:

• El Niño and La Niña (a year or so)
  Much of the warmth in the last year or so has been due to a strong El Niño, we've left that and now have La Niña "conditions." Like recessions, it takes several months of "conditions" before scientists declare what is obvious to everyone.

• A solar Schwabe cycle (10-12 years)
  We are in Solar Cycle 25, predicted to very weak compared to the last few active cycles.

• Pacific or Atlantic Multidecadal Oscillations (50-70 years)
  The Pacific cycle (PDO - Pacific Decadal Cycle) may be the major climate driver over a human lifetime. It recently flipped to its cool phase. The warm AMO brings a much higher tropical storm rate in the Atlantic, though short term effects like El Niño greatly suppresses storm development.

• The solar Suess cycle (210 years)
  The Year Without a Summer was 1816, during the Dalton Sunspot Minimum that included several cool years before the explosion of Mt. Tambora in 1815.

• The precession of the equinoxes (24,000 years)

• Ice Ages (100,000 years et al)

How hot was summer 2010? My unofficial result from unofficial data from the Concord NH National Weather Service station is an average temperature of 69.4°F. That's the hottest summer (June, July, and August) on record, and those go back to 1895, and it beats the old record from 1949 and 1955 by a substantial margin, 1.4°.

Alarming? Well, no. Summer 2009 was only 63.8°F, the 20th coldest summer in the record. While the northeast had a hot summer, the northwest had a cool summer with complaints about chilly weather reaching down the coast. to San Diego. The continental United States is only 3% of the Earth's surface, what happens in New Hampshire has only a very small impact on global averages.

Ah, but the weather is getting more variable, right? Perhaps. I haven't studied that closely, but I noticed the following data from the early part of New Hampshire's summer temperature record. The accompanying graph includes two warm peaks from the PDO cycle, a bigger climate driver than the CO2 changes over the same period.

Year Temp Rank 1895 66.9 103 1896 66.6 97 1897 64.0 25 1898 66.9 103 1899 65.6 74 1900 66.9 103 1901 67.2 110 1902 62.1 3 1903 61.1 1

I've seen few, if any, rigorous comparisons of weather variability over time, pretty much everything I've heard has been anecdotal.

Hurricanes (tropical cyclones in geek speak)

There are lots more hurricanes, right?

Well, sort of. In 1995 the Atlantic entered a period of much more activity. This wasn't due to global warming, but a shift in an Atlantic ocean wind and water pattern called the AMO. The last active period was in the 1940s to 1960s and included three major hurricanes in New England. We've been very lucky we've had not hurricanes of note yet in this period.

Globally, tropical cyclone activity is scraping along at a 30 year low, the prediction that global warming means more tropical cyclones isn't panning out.

Warming? Climate Change?

Climate is always changing, and changes on almost any time period you might examine. We've reached the end of a warming period due to the PDO and cooling began in 2008. It was interrupted by the recent El Niño, and that is giving way directly to La Niña. Atmospheric temperatures tend to lag La Niña by a few months, and we're ready to see cooling set it. This may be the last good time to convince people that global warming is still going on, as some of the seasonal forecasts are expecting a lot of cold weather. If I were you, I'd split an extra cord of wood for this winter.

Contact Ric Werme or return to his home page.

Written 2010 Sep 9, last updated 2010 Sep 9.