Even though increasing atmospheric CO2 concentrations are a factor that will contribute to increasing global temperatures, the Earth's climate is complex and there are ways it can cool -- changing cloud cover and ocean circulation being two ways. The perception of a "precipitous" decline is based on starting at a high point -- an El Nino year in 1998 -- and the current end point, a year influenced by a strong La Nina. The oceans are a significant enough factor that you can have such swings even with increasing atmospheric CO2.
I thought of a general analogy (people always nitpick analogies, but I stupidly keep trying). Imagine a baseball player with a career .250 average. In spring training, the hitting coach helps him make an adjustment. In the first month of the season, the player hits .315. The next month, .330. The next month, .299. Then he has a bad month and hits .225. He gets it back a bit and in the next two months hits .275. and .290.
So his year (by month) was .315, .330, .299, .225, .275, .290.
Questions: 1. Is he a better hitter this year than for his career? 2. During his bad month and his decline from .330 to .225, would you say he was a better or worse hitter than for his career? 3. Do you think one season is sufficient to really evaluate if he's a better hitter than before the adjustment was made? (The motivation behind this analogy is that in a complex system -- and hitting a baseball in competition has a lot of associated variables -- it is very possible to have a longer-term increasing trend with periods of decrease. To really evaluate the direction of the trend, it's necessary to have long-term data, and when analyzing the data, it's necessary to be aware of potential biasing factors.)
Here's another article, perhaps less pejorative, and from scientists. These scientists do have a clear POV, but this particular subject has generated a lot of discussion, so there's a lot out there.
Waiting for Global Cooling (PDF)
I'm currently very curious about the quietude of the Sun. This might influence temperatures globally if it continues, i.e. if the new solar cycle doesn't get going and the Sun actually enters into a new sunspot minimum period. However, I've predicted before here on FR that the next year with an average or bigger El Nino will set a new global temperature record, and I stand by that prediction no matter what the Sun does over the next few years. I even predict that there will be a new global temperature record by 2013 even if there isn't an El Nino year between now and then, but I think the odds are that there will be an El Nino year by then.
I have a bit about models in my profile, if you care to take a look.
There is more that we could discuss but I'd rather leave it at this for now.
1. Is he a better hitter this year than for his career?
In the real world, his batting average would be determined by his at bats and hits. You can't add up the months to get his annual average without assuming that he had the same number of official at bats each month. It is a running average, which is why we have the batter's up to date average on a daily basis. That aside, just to stay with the analogy, he had an above average career year, i.e, .289. Depending on the length of his career, this year could have a major impact on his career batting average, e.g., this is his second year in the league.
During his bad month and his decline from .330 to .225, would you say he was a better or worse hitter than for his career?
I wouldn't make such an assumption. You don't make such assumptions without more data. He could have been injured, had fewer at bats, or was in slump. I notice from your example that during the first three months, his average was .315, .330, and .299. What happens if he produces similar numbers for the rest of the season and does it again next season? Is the second season also an anomoly? Is past performance an indicator of future performance?
Do you think one season is sufficient to really evaluate if he's a better hitter than before the adjustment was made? (The motivation behind this analogy is that in a complex system -- and hitting a baseball in competition has a lot of associated variables -- it is very possible to have a longer-term increasing trend with periods of decrease. To really evaluate the direction of the trend, it's necessary to have long-term data, and when analyzing the data, it's necessary to be aware of potential biasing factors.)
All analogies breakdown after awhile. Using your analogy, what if the player's career spanned several billion years? And he had a history of flucuating batting averages so that every 11,000 years or so he would go into prolonged slumps or go on a hitting tear. However, we didn't have good records for most of his career and had to depend on some very old, poorly kept records, i.e, the only really accurate records just spanned 11,000 years to the present. We also know that there are hundreds of variables that affect his hitting and that his current batting average marks niether his highest or lowest average.
Can we predict what his average will be next year or for the next 11,000 years? And how useful is the career average in predicting it.
In the 1970s, the "scientific consensus" {an oxymoron] was that we were heading into a prolonged period of cooling. Now it is global warming and climate change, which is disputed by many reputable scientists who disagree with the models and the assumptions. The earth's climate has always been cooling or warming. It is a natural cycle.
Questions: How long must the earth continue to cool before it is accepted as a trend? Do you disagree with the data that show the earth is cooling and has been since 2001?
However, I've predicted before here on FR that the next year with an average or bigger El Nino will set a new global temperature record, and I stand by that prediction no matter what the Sun does over the next few years. I even predict that there will be a new global temperature record by 2013 even if there isn't an El Nino year between now and then, but I think the odds are that there will be an El Nino year by then.
LOL. You have enough El Nino qualifiers to cover all the bases. I predict that we will have a very cold winter this year and the earth will continue to cool for the next 10 years.