A Q&A 4

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1. 

   dobermanmacleod Posted 12:30 am
   10 Sep 2006

   Abrupt climate changeClimate models are bias against abrupt climate change events, instead forecasting gradual changes.
   The climate goes from one steady state to another without warning.  Our current Holocene steady state of warm wet weather will be replaced by a hotter dryer state which historically resulted in mass extinction.
   With CO2 levels higher than at least in the last 800,000 years, and they continue to increase dramatically, it is predictable that we will soon, suddenly, experience expotential temperature rises.
   I suggest listening to Dr Lovelock, who says the earth will reset it's thermostat 10C in the next decade or two.
   To reiterate-it is probable that soon we will experience abrupt climate change-a normal and historically reasonable event.

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2. 

   Backcut Posted 1:36 am
   10 Sep 2006

   Fascinating stuffAs an amateur meteorologist, intricately woven into my job and hobbies, I've come to appreciate the complexities of weather forecasting. I've not pretended to know the intricacies of long-range modeling but, I've marveled at the people like Marvin Dodge, who used ocean currents in his moderate range forecasts.
   Of course, we can expect continued "feast and famine" in regards to precipitation on the West coast. I've also, long ago, bought into the high probability that our human activities do affect our climate. I never needed an Al Gore to prove that to me.
   One thing that puzzles me is: How can the wildfire danger get any worse in southern California? It used to be, back before "climate change", that the LA area would have massive wildfires EVERY year. Now, it seems to be hit and miss. It could be that public awareness and fire prevention technology has reduced the occurence of big fires. However, fuels are always growing and it's only a matter of time before those areas burn again.
   One thing that scares me is a report I saw many weeks ago that states that previous forest practices will not have any effect on western wildfires. It also stated that "climate change" is the driving force behind all of our wildfires. I cannot and will not disbelieve my own eyes. The Tahoe Basin is a perfect example of how we've radically changed the forest from a fire-adapted and balanced ecosystem into an overgrown tinderbox in a lightning-prone area. (I was a fire lookout for two years, high above the north shore of this "Jewel of the Sierra".)
   
   Scenic pics at http://lhfotoware.blogspot.com

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3. 

   Kit Stolz Posted 2:46 am
   10 Sep 2006

   SoCal FiresBackcut makes a good point about fires in SoCal. It's absolutely true that the region has always had huge Santa Ana-driven fires. I talked to a fire ecologist named Richard Minnich, at UC Riverside, who recounted newspaper reports from the 1880's which discussed a fire in what is today Orange County that is believed to have been three times the size of the huge fire in San Diego in 2003.
   But the number of big fires and the amount of acreage burned is up substantially in recent decades. After discussing the issue extensively with a variety of scientists, I think it's fair to say that climate change is not the reason why. Other factors look more important. "Type conversion" in the desert, from native plants to weeds like cheatgrass may have contributed to damage done to ancient palms in desert fires this year. And Westerling (mentioned above) thinks SoCal will likely experience more drying and drought, which if true is not going to help.
   But the bigggest factor, as identified by a fire researcher named Jon Keeley, with the USGS, is very simple. Virtually all fire starts in SoCal are human-caused, either maliciously or carelessly  or from power line arcing. Keeley compared big fires in Southern California in recent decades with big fires along the central coast, where the environment is not hugely different...but the population hasn't grown much. The result? The number of fires in SoCal has soared with population growth, whereas the number of fires along the central coast, where population has been relatively constant, have stayed relatively low.

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4. 

   dobermanmacleod Posted 9:34 pm
   10 Sep 2006

   An abrupt climate change primerRecent scientific evidence shows that major and widespread climate changes have occurred with startling speed.
   
   This new paradigm of an abruptly changing climatic system has been well established by scientific research, but this new thinking is little known and scarcely appreciated in the wider community.
   Asked about the discovery of abrupt climate change, many climate experts today would put their finger on one moment: the day they read the 1993 report of the analysis of Greenland ice cores.
   The most recent abrupt climate change, known as the "Younger Dryas," took place on earth roughly 11,400 years ago.  At that point the earth was warming rapidly, but was abruptly plunged into cold, dry, and windy glacial conditions.  It remained frigid for twelve centuries before abruptly warming again.
   Warm interglacial periods are generally subject to big swings of temperature lasting for centuries. The last 10,000 years, known as the "Holocene," has been by far the longest stable warm period during the past half million years.
   The entire rise of human civilization since the end of the Younger Dryas has taken place during a period of warm and stable climate that is unique in the long record.  Temperatures as high as those of the Holocene have only occurred about 10% of the time during the past half million years.
   Why do large and rapid changes in climate periodically overtake the planet?
   Technically, an abrupt climate change occurs when the climate system is forced to cross some threshold, triggering a transition to a new state.  Whenever pushed, it didn't lead to smooth changes in earth's climate, but rather to jumps from one state to another.
   The earth's climate does not respond to forcing in a smooth and gradual way.  Complex systems like the atmosphere and ocean currents are known to move from one steady state to another with only very brief transitions in between.
   Abrupt climate changes are especially common in history when the climate system was being forced to change most rapidly.  Thus, greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events.
   Changes in temperature differences alter the circulation of the atmosphere-this is what is most important to societies: not the temperature changes themselves, but how these changes affect precipitation patterns over time-where in the world it rains or snows and how little or how much.
   Dramatic changes in water resources have enormous consequences on human populations, generating famines, migrations, civilizations foundations and collapses. Abrupt climate change took hold of many of humanity's great civilizations and shook them until they collapsed. Year-in and year-out, over the long haul, drought extracts the most from humanity.
   The earth has experienced large and rapid climate oscillations on a scale that human agricultural and industrial activities have not yet faced.
   
   

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