Friday, June 19, 2009

Climate dogs that won't hunt

Remember the cold weather of January, February and March?

They were days and nights so chilly that some climate change deniers of my acquaintance actually cited them as proof against climate warming.

Well, that's just so last season.

April warmed up some. The fifth warmest April since records have been kept. Here's the citation for that, from NOAA:

Next? May was hot, too. The fourth warmest ever. Here's that citation:

As you might expect from those figures, the spring season as a whole is also turning out pretty warm. March to May had the fifth warmest record for any northern hemisphere spring.

It wasn't that hot everywhere all the time, of course. In fact, NOAA cites Hawai'i's cool late winter and early spring:

“March-May 2009 temperatures were above average across Mexico, Europe, southern South America, northwestern Alaska, northwestern and southern Africa, parts of Australia, and most of the contiguous U.S., and Asia. Cooler-than-average temperatures occurred across the Hawaiian Islands, Canada, and parts of the north central and northwestern United States,” the agency said.

Climate, after all, is variable on any number of scales. It's variable over time. It's variable over geography. If you can't step back and see the bigger picture, it's hard to draw reasonable conclusions.

The graphic at the upper right of this post shows how January to May temperatures around the world have differed from the average since about 1880. Over an extended period of time, the short-term variations fall into the background and the warming trend is quite clear.

But it is also clear that there's a significant amount of variability within the larger trend.

Some folks point to the flat to downward trend of the past five or six years as proof of a cooling climate. That's a little like claiming that a cool week in February is proof of cooling.

To descend into hackney, we'll just say this: That dog won't hunt.

© Jan TenBruggencate 2009


Duncan said...

The NOAA dataset is unreliable. NASA's data shows May to have been a little colder than average for the 30 years of satellite data.

Don't believe everything you read on the internet.

Jan T said...

Thanks for the comment. I have studied the NASA data and find that NASA's satellites support the larger climate change premise. Your cite alleges a cooling trend over recent years. Here's NASA's own assessment from the year 2008: "Calendar year 2008 was the coolest year since 2000, according to the Goddard Institute for Space Studies analysis [see ref. 1] of surface air temperature measurements. In our analysis, 2008 is the ninth warmest year in the period of instrumental measurements, which extends back to 1880 (left panel of Fig. 1). The ten warmest years all occur within the 12-year period 1997-2008. The two-standard-deviation (95% confidence) uncertainty in comparing recent years is estimated as 0.05°C [ref. 2], so we can only conclude with confidence that 2008 was somewhere within the range from 7th to 10th warmest year in the record."

Toronto Realtor said...

I must agree with Duncan, NOAA has always supplied us with unreliable data that came from doubtful sources. What we see her is definitely a cooling trend but also a disappearance of spring and fall. Maybe it's just me but lately all springs have been very cold and then suddenly turned into summer-like weather. Same with fall weather but reversed of course. I wonder if there is any research done on that topic.

Take care, Elli