Tree rings are tree rings. 25 years are not going to change the tree ring history a bit.
I wonder if any new information has surfaced in the quarter century that's gone by since your paper was written.
I don't know, but I did look for more current studies. My point of course is that droughts in California are not unusual. I did find a relatively recent OPED though that confirms low drought activity the past 150 years but it does manage to blame potential future drought severity and frequency on global warming. I aim to please!I wonder if any new information has surfaced in the quarter century that's gone by since your paper was written.
Drought a fact of California life; planning can ease impact
Historical climate studies reveal that, over the last two millennia, California has experienced major and sudden shifts in the frequency and severity of droughts. In the Middle Ages, two dry spells lasted more than 140 years and 220 years, respectively, albeit with intermittent wet periods. The frequency of statewide droughts over the last 150 years, moreover, has been below average. In some centuries, California has suffered from as many as a dozen major multiyear droughts.
Climate change increases the risk of an unusually severe drought. Climate models do not agree on whether mean precipitation will decrease over the remainder of this century, although they predict a decline if no steps are taken soon to address greenhouse-gas emissions. Rising temperatures, however, will lead to increased evapotranspiration (evaporation plus the loss of water from plants), a declining snowpack and earlier runoff, all resulting in less water available in an average year for consumption. More importantly, climate change will lead to more frequent, longer and harsher droughts.
http://www.researchgate.net/publica...101_B.C._recorded_in_giant_sequoia_tree_rings
But, but global warming!
I don't know, but I did look for more current studies. My point of course is that droughts in California are not unusual. I did find a relatively recent OPED though that blames potential future drought severity and frequency on global warming. I aim to please!
http://www.sfgate.com/opinion/article/Drought-a-fact-of-California-life-planning-can-5172660.php
In particular, during the medieval period, ∼AD 9001300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management.
Tree rings are actually quite good proxies for droughts. As a temperature proxy, not so good...especially since 1960.Tree rings are tree rings. 25 years are not going to change the tree ring history a bit.
Climate-change projections clearly indicate what observations already suggest: Temperatures everywhere will be warmer in the future due to anthropogenic activities. General circulation models (GCMs) project continued warming, with annual temperatures 35 °C above current levels by the end of the century (1).
In other words, you aren't able to comprehend climate modeling, so you reject it.In other words...no.
I like the way you think! Despite over 2,000 years of historical data indicating much higher drought severity and frequency due to natural variation, you manage to imagine exactly what caused the slight uptick the past 65 years! All things now become possible with this kind of thinking! You sir, get a gold star for creative rationalization! Kudos!So your saying CA was trending towards less droughts until 1950. I wonder what could have changed in the last 65 years to change the trend?
:hmm:
I've discussed climate modeling at length in other threads. If I had more time I would engage here...but unfortunately I don't right now. Maybe later.In other words, you aren't able to comprehend climate modeling, so you reject it.
Also from your study:
Glad to see you're on board!
Because, clearly, it's impossible to tell the difference between - on the one hand - big cities in Syria whereI believe this, look at the effects global warming has had in large US cities. Many are like war zones.
and - on the other hand, big cities in America where modern water systems, almost no corruption, essentially unchanged populations, much less discrimination, a much healthier economy, and much less severe climate-change-induced effects have caused no major disruptions in day-to-day life.the country had been mired in a three-year drought—its worst in recorded history. Government agricultural policies had led to an overreliance on rain, so desperate farmers had to turn to well water—and they ended up sucking most of the country’s groundwater reserves dry. What happened next upended the country. “A lot of these farmers picked up their families, abandoned their villages, and went en masse to urban areas,” says Colin Kelley, a climate scientist at the University of California, Santa Barbara and author of a new paper on the conflict. Add 1.5 million refugees fleeing the US-led invasion of Iraq, and the population of Syrian cities grew by 50 percent between 2002 and 2010. The influx led to illegal settlements, rampant unemployment, and inequality. But the government hardly did anything in response (corruption didn’t help, nor did the fact that the hardest-hit areas were populated by Kurdish minorities, who have long been discriminated against and ignored). Soon, frustrations boiled over.
Yes, to the right-wing mind, the term "climate change" means identical circumstances everywhere. Because complexity and nuance are not allowed.
You mean how Republican legislators gather snow from outside, tell us it's colder than usual, and conclude that climate change cannot be a valid scientific theory?"Climate change" means looking outside your window and blaming today's weather on CO2. Give it a try, it's fun and I'm sure you're up for the challenge.
The scientific value is the same.You mean how Republican legislators gather snow from outside, tell us it's colder than usual, and conclude that climate change cannot be a valid scientific theory?
I like the way you think! Despite over 2,000 years of historical data indicating much higher drought severity and frequency due to natural variation, you manage to imagine exactly what caused the slight uptick the past 65 years! All things now become possible with this kind of thinking! You sir, get a gold star for creative rationalization! Kudos!
I must have missed the part where they conclusively ruled out the possibility natural variation. But I did read that the part of the study that "suggested" AGW increased the "probability" of warm-dry conditions.Or it might be the climate study I linked too.
I must have missed the part where they conclusively ruled out the possibility natural variation. But I did read that the part that "strongly suggests" AGW.
Are we seeing some of these effects already? Since 2012, California has been in the midst of a record-setting drought, with extremely warm and dry conditions characterizing the last three years in that state. A new paper published in the Proceedings of the National Academy of Sciences concludes that warming caused by humans is responsible for the conditions that have led to this California drought.
This study, published by scientists affiliated with the Department of Environmental Earth System Science and the Woods Institute for Environment at Stanford University, used historical statewide data for observed temperature, precipitation, and drought in California. The investigators used the Palmer Hydrological Drought Index (PHDI) and the Palmer Drought Severity Index (PDSI), collected by the National Climatic Data Center, as measures of the severity of wet/dry anomalies. They also used global climate model simulations from the Coupled Model Intercomparison Project (CMIP) to compare historical predictions for anthropogenic and non-anthropogenic historical climates.
From NOAA.From the article about the study.
Is the California Drought a symptom of long term climate change?
The current drought is not part of a long-term change in California precipitation, which exhibits no appreciable trend since 1895. Key oceanic features that caused precipitation inhibiting atmospheric ridging off the West Coast during 2011-14 were symptomatic of natural internal atmosphere-ocean variability. The current drought is not part of a long-term change in California precipitation, which exhibits no appreciable trend since 1895. Key oceanic features that caused precipitation inhibiting atmospheric ridging off the West Coast during 2011-14 were symptomatic of natural internal atmosphere-ocean variability.
Model simulations indicate that human-induced climate change increases California precipitation in mid-winter, with a low-pressure circulation anomaly over the North Pacific, opposite to conditions of the last 3 winters. The same model simulations indicate a decrease in spring precipitation over California. However, precipitation deficits observed during the past three years are an order of magnitude greater than the model simulated changes related to human-induced forcing. Nonetheless, record setting high temperature that accompanied this recent drought was likely made more extreme due to human induced global warming.
Re: Western United States droughts. California in particular...
Imagine what they will be telling us when the medieval droughts (200+ years) return. The ones in our recorded (160+ year) history are child's play.
You telling us natural past occurrences cannot repeat except via man? How do you know? I'll wait.Oh so those large droughts are returning? How do you know? I'll wait.
You telling us natural past occurrences cannot repeat except via man? How do you know? I'll wait.
Hey.. I'll throw you a bone. Medieval Warm Period, 950-1250. Little Ice Age follows that to provide relief, but soon as we warm up again... perhaps the Western United States dries up.
Well if war does come to California, we'll know that global warming may have caused their drought and that it may have been a factor causing the war....just like Syria. There is NOTHING conclusive here...just speculation and sensationalism. Is this the kind of science you want us to believe in?
You made the claim they were returning not me.
I already provided you a scientific article that explains the increased risk of drought in CA via MMGW.
Your link describes the conditions but provides no reason why it occurred in the first place.
So what makes you think natural variation is going to produce medieval warm period level droughts in CA. I'll keep waiting.