Get ready for the refrain of the nutters: " Cool 2008 warms climate debate"

[depakid]

You may have already seen and heard variations of "it's been so cold here that..." from dozens of sources over the past few months.

From the Murdoch paper The Australian:

WHILE the official figures are not yet in, 2008 is widely tipped to be declared the coolest year of the century.

Whether this is a serious blow to global warming alarmists depends entirely on who you talk to.

Anyone looking for a knockout blow in the global warming debate in 2008 were sorely disappointed. The weather refused to co-operate, offering mixed messages from record cold temperatures across North America to heatwaves across Europe and the Middle East earlier in the year.

Even in Australia yesterday there were flurries of snow on the highest peaks of a shivering Tasmania, while the north of the country sweltered in above-average temperatures. A cool 2008 may not fit in with doomsday scenarios of some of the more extreme alarmists. But nor, meteorologists point out, does it prove the contrary, that global warming is a myth.

<snip>

One of Australia's best-known sceptics of man-made global warming, former head of the National Climate Centre William Kininmonth, said the cool year did not fit in with the greenhouse gas theory that suggests the globe should be continuing to warm.

"All the reports from the northern hemisphere of record snows and freezing temperatures would suggest that 2008 will follow the predictions and officially be declared the coolest of the century," he said. "But the only thing we can really deduce is that the warming trend from the mid-1970s to the late 1990s appears to have halted."

Another well-known sceptic, geologist Bob Carter, said critics were jumping on the cold northern hemisphere winter to dismiss global warming, but climate was a long-term phenomenon and there was nothing particularly unusual about present circumstances.

But Don White, of consultancy firm Weatherwatch, said while last year was likely to end up the coolest year this century, this needed to be put into perspective. "If the same temperatures had occurred in the early 1990s it would have been the warmest ever," he said.

"The year 2008 may have been colder than the previous seven years, but it was still warmer than most years prior to 1993."

http://www.theaustralian.news.com.au/story/0,25197,24861265-601,00.html

[Wabbajack_]

1. I just walked by dog. My face is frozen.

[Dead_Parrot]

3. I just walked my dog. My whole body is sweating.

Maybe it depends where we are? :shrug:

[Wabbajack_]

5. I'm in Chicago

and a couple weeks ago it was like -30 windchill. Dayum. Today is balmy is comparison but still cold.

[Dead_Parrot]

6. I'm in New Zealand, nr Wellington,

And it's hot and muggy. Stupidly so: I stopped sweating around 2AM.

So, do we assume local weather is indicative of global climate, or do we assume global climate is indicative of local weather?

Or both?
Or neither?

:shrug:

[Wabbajack_]

8. Ha

well it's summer in your hemisphere and winter in mine. That explains that.

[Dead_Parrot]

2. Sigh

It's funny how people who don't give a shit about the hottest year in x years suddenly wake up when it's the least-hot

Ho hum. Here's the meat

The great thing about complex data is that one can basically come up with any number of headlines describing it - all of which can be literally true - but that give very different impressions. Thus we are sure that you will soon read that 2008 was warmer than any year in the 20th Century (with the exception of 1998), that is was the coolest year this century (starting from 2001), and that 7 or 8 of the 9 warmest years have occurred since 2000. There will undoubtedly also be a number of claims made that aren't true; 2008 is not the coolest year this decade (that was 2000), global warming hasn't 'stopped', CO2 continues to be a greenhouse gas, and such variability is indeed predicted by climate models. Today's post is therefore dedicated to cutting through the hype and looking at the bigger picture.

As is usual, today marks the release of the 'meteorological year' averages for the surface temperature records (GISTEMP, HadCRU, NCDC). This time period runs from December last year through to the end of November this year and is so-called because of the fact that it is easier to dice into seasons than the calendar year. That is, the met year consists of the average of the DJF (winter), MAM (spring), JJA (summer) and SON (autumn) periods (using the standard shorthand for the month names). This makes a little more sense than including the JF from one winter and the D from another as you do in the calendar year calculation. But since the correlation between the D-N and J-D averages is very high (r=0.997), it makes little practical difference. Annual numbers are a little more useful than monthly anomalies for determining long term trends, but are still quite noisy.

The bottom line: In the GISTEMP, HadCRU and NCDC analyses D-N 2008 were at 0.43, 0.42 and 0.47ºC above the 1951-1980 baseline (respectively). In GISTEMP both October and November came in quite warm (0.58ºC), the former edging up slightly on last month's estimate as more data came in. This puts 2008 at #9 (or #8) in the yearly rankings, but given the uncertainty in the estimates, the real ranking could be anywhere between #6 or #15. More robustly, the most recent 5-year averages are all significantly higher than any in the last century. The last decade is by far the warmest decade globally in the record. These big picture conclusions are the same if you look at any of the data sets, though the actual numbers are slightly different (relating principally to the data extrapolation - particularly in the Arctic).

So what to make of the latest year's data? First off, we expect that there will be oscillations in the global mean temperature. No climate model has ever shown a year-on-year increase in temperatures because of the currently expected amount of global warming. A big factor in those oscillations is ENSO - whether there is a a warm El Niño event, or a cool La Niña event makes an appreciable difference in the global mean anomalies - about 0.1 to 0.2ºC for significant events. There was a significant La Niña at the beginning of this year (and that is fully included in the D-N annual mean), and that undoubtedly played a role in this year's relative coolness. It's worth pointing out that 2000 also had a similarly sized La Niña but was notably cooler than this last year.

[ixion]

4. global 'warming' is a buzz phrase... more appropriate is global climate change

because even during a so-called "global warming" there would be areas that would still be cold.

The over-simplification by folks who say "hey, it's snowing like crazy, I guess there's no global warming", is just plain silly.

[summer borealis]

7. So correct

To say a wave of weather refutes climate change is like saying ...
"I feel good today, I must not have cancer anymore!"