Friday, May 07, 2010

On climate

Temperatures since the last ice age. From which the individual who did the graph concludes:

In other words, we’re pretty lucky to be here during this rare, warm period in climate history. But the broader lesson is, climate doesn’t stand still. It doesn’t even stand stay on the relatively constrained range of the last 10,000 years for more than about 10,000 years at a time.

Does this mean that CO2 isn’t a greenhouse gas? No.

Does it mean that it isn’t warming? No.

First analysis to make sense of both the global warming and global cooling materials I have read.

Bottom line, "In fact for the entire Holocene — the period over which, by some odd coincidence, humanity developed agriculture and civilization — the temperature has been higher than now, and the trend over the past 4000 years is a marked decline. From this perspective, it’s the LIA that was unusual, and the current warming trend simply represents a return to the mean. If it lasts"

I've wondered. The solutions I keep seeing for the current problems don't match the predictions. They are all "deck chairs on the Titanic" sorts of things.

That is the temperatures that include the medieval warm period -- note that the current rise is still well below those temperatures.

That doesn't mean that there are not potential problems, etc. It just puts them into a different scope. Read the article for the graphs and the fact summaries.


Jared* said...

I'm not a climate scientist, but I think several points need to be made:

1. You cannot compare temperature variations in one place with global averages. Your source is only looking at Greenland.

2. The most recent data on the graph is from ~95 years ago. However, much of the anthropogenic global warming has occurred since 1980. So those graphs don't give proper context to the current state of climate. (For more see here.)

3. Finally, the whole argument is somewhat of a red herring. See the following FAQs from the 2007 IPCC report:

Is the Current Climate Change Unusual Compared to Earlier Changes in Earth’s History?


What Caused the Ice Ages and Other Important Climate Changes Before the Industrial Era?.

I hope that helps.

Stephen said...

Jared, it is interesting that my source would agree with you that The concentration of CO2 in the atmosphere has reached a record high relative to more than the past half-million years, and has done so at an exceptionally fast rate.

It would also agree with you that a low of 180 ppm during cold glacial times and a high of 300 ppm during warm interglacials. Over the past century, it rapidly increased well out of this range, and is now 379 ppm (see Chapter 2). For comparison, the approximately 80-ppm rise in CO2 concentration at the end of the past ice ages generally took over 5,000 years. Higher values than at present have only occurred many millions of years ago

But the analysis does make sense of the proposed solutions. Given the oncoming global economic collapse or close brush with same, I expect that we will see a number of developments. I'm hoping that we will work through them all without disaster.