SEARCH BLOG - GLOBAL WARMING
To help clarify for those who didn't pick up what I was saying in the prior post, this is from the NASA link at the right side of the page: NASA - Earth's Fidgeting Climate
The ant on the hour hand
"For the ordinary person, it's a common misperception that weather is not changing ... that last winter is about as cold as this winter and last summer is about as warm ... and the world is pretty much constant," Krabill said. "That's not true. The Earth has gone through and continues to go through cycles of warming and cooling. It's just natural."
This natural variability often shows an astounding degree of complexity, much of which remains poorly understood.
"We've only begun making (large scale) measurements in the last 100 to 150 years," Abdalati said. "And climatic processes happen on very different time scales. There are some, like ice ages, that are in the tens of thousands or hundreds of thousands of years long. An then there are atmospheric processes like weather, which happen on the scales of hours and days."
Other climate cycles fall in between, such as the North Atlantic Oscillation mentioned above, which is thought to complete one cycle roughly every 20 to 30 years.
"And so you have all these processes mixed together that have been going on for thousands of years, and you're in the difficult position of trying to separate something very recent from the natural cycle without fully understanding what that natural cycle is," Abdalati said.
Left: Knowing where a relatively short interval of observation fits into the long-term pattern is a difficult challenge for scientists. A steady increase that appears to be a trend may be a trend, but it may also be a small part of a larger cycle.
Observing a system like climate that varies on several time scales -- some of which approach geological slowness -- could be likened to an ant watching the hands of a clock, "perhaps with the ant sitting on the hour hand," Abdalati added.
Seen in this context, scientists don't give much weight to the five-year snapshot of the ice on Greenland.
"You know, five years is a pretty short amount of time in glaciological terms," Krabill said. "To try to make inferences about 'Global Climate Change' in capital letters from a five-year period of time is a pretty risky business."
Other modern data sets are not much longer. The era of satellite observation is only about 30 to 40 years old -- a mere blink in climatological terms. And the widespread network of weather-measurement stations in the developed world is about 150 years old.
So, I guess "Anonymous" was right that I understated this issue as "not major." It doesn't deny that there has been recently observed global warming, but it does reinforce the need to understand that we don't really understand what is happening... and that those who haven't jumped on the anthropogenic-based-CO2-driven-climate-change-bandwagon are not necessarily "fringe skeptics."What I have said and continue to say is:
- over a short span, there is great uncertainty regarding the implications of global temperature change
- any perceived relationship between longer term climate changes and human influences is still open to further investigation