Go to the National Snow and Ice Data Center for a nice interactive graphic on the extent of arctic sea ice. Click on 2013 and compare it to recent years. Discuss.
All posts tagged AGW
Posted by Fred on June 25, 2013
A nice (English language) interview with Dr. Hans von Storch at Der Spiegel is well worth a read. It is nice to see climate scientists valuing the observational record, even if it is inconsistent with the predictions of climate models. Speaking of which, he seems to agree that we are well outside a 95% confidence level that the various climate models are wrong. That doesn’t mean we don’t have warming, or that there isn’t an anthropogenic component, or even that the earlier predictions of significant warming are mistaken. But it does lower the confidence rational people should have in the accuracy of the current climate models.
I also completely agree with this:
Unfortunately, some scientists behave like preachers, delivering sermons to people. What this approach ignores is the fact that there are many threats in our world that must be weighed against one another.
Anthropogenic Global Warming is “the global threat of our time,” as President Obama recently said, only until we detect an Earth intersecting asteroid, or a supervolcano goes off, or we get a 1918-style global pandemic, or a Carrington Event occurs, or a thousand other scary scenarios that could happen. We shouldn’t close our eyes to the very real dangers that could come our way.
Posted by Fred on June 25, 2013
The evidence for major climate change in the 17th century is both copious and unambiguous. Consider the year 1675. In July, the Paris socialite Madame de Sévigné complained to her daughter, who lived close to the Mediterranean: “It is horribly cold: We have the fires lit, just like you, which is very remarkable.” She added: “We think the behavior of the sun and of the seasons has changed.”
Judith Curry points us to a study of the 17th century climate in in The Inevitable Climate Catastrophe. She has extensive quotes from Geoffrey Parker’s new book “Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century.” It is well worth a read, for this lesson if nothing else:
Nevertheless, it took human stupidity to turn crisis into catastrophe.
The historical record is also a great cautionary tale that cooling is much, much worse than warming. And, since a static climate is as unrealistic as a static universe…
Posted by Fred on June 5, 2013
So, should we worry or not about the warming climate? It is far too binary a question. The lesson of failed past predictions of ecological apocalypse is not that nothing was happening but that the middle-ground possibilities were too frequently excluded from consideration. In the climate debate, we hear a lot from those who think disaster is inexorable if not inevitable, and a lot from those who think it is all a hoax. We hardly ever allow the moderate “lukewarmers” a voice: those who suspect that the net positive feedbacks from water vapor in the atmosphere are low, so that we face only 1 to 2 degrees Celsius of warming this century; that the Greenland ice sheet may melt but no faster than its current rate of less than 1 percent per century; that net increases in rainfall (and carbon dioxide concentration) may improve agricultural productivity; that ecosystems have survived sudden temperature lurches before; and that adaptation to gradual change may be both cheaper and less ecologically damaging than a rapid and brutal decision to give up fossil fuels cold turkey.
I couldn’t have said it better myself. In the midst of a rather good Wired (yes, Wired!) article, this is a spot on description of the lukewarmist stance.
Posted by Fred on August 18, 2012
Damp winters on the edge of Dartmoor were taking their toll, so in recent years he has overwintered in St Louis, his wife’s hometown in Missouri. The experience altered his attitude to the politics and economics of energy.
Read the whole thing. The infirmities of age, combined with wintering over in the US, have changed many of his ideas.
I liked this quote, too. “He says he largely dismantled his home laboratory 10 years ago when he ended his life as a practising scientist: “I have become a thinker since then. There is so much more to do. I think retirement means death.”
Posted by Fred on June 17, 2012
“The Sun makes fantastic natural experiments” Henrik Svensmark says, “that allow us to test our ideas about its effects on the Earth’s climate.” Most dramatic are the events called Forbush decreases. Ejections of gas from the Sun, carrying magnetic fields, can suddenly cut the influx of cosmic rays coming to the Earth from exploded stars.
CERN’s CLOUD experiment has just published a paper on the effect of cosmic rays on aerosols that can affect cloud formation. I’ll have something to say on that shortly, but Nigel Calder gives a good writeup on other experimental evidence for cosmic rays affecting cloud formation. It is a bit long, but an important read for anyone who wants to understand Dr. Svensmark’s hypothesis. The executive summary: Svensmark demonstrates experimental evidence for GCR influence on cloud formation, and explains the reason critics failed to find such evidence.
Posted by Fred on August 27, 2011
Added: I’ve added a bit to the post, in italics, after some reflection and looking for satellite measurements of SO2. Quick take: we’ve only had satellite data sensitive enough to monitor fossil fuel SO2 contributions for 5 years or so. I haven’t found trend data yet, but I’ll keep looking.
A recent paper from a team of statisticians at Boston University contains a claim that the lack of global warming during the first decade fo the 21st century is due to the cooling effect of sulfur emissions from Chinese coal plants. It is an interesting hypothesis, physically plausible, but I’m still digesting the paper. Here are a few musings after a read through.
Volcanoes can cause measurable global cooling due to SO2 emissions. However, a large volcanic eruption injects sulfur compounds high into the stratosphere where they are distributed widely across the global and linger for several months. As I understand it, coal-fired power plant stack emissions do not reach the stratosphere in any large amounts and are mostly confined to the troposphere. There are transport mechanisms for bosoting fossil fuel sulfer emissions into the stratosphere (e.g., thunderstorms) so the steady increase will add to the stratospheric SO2 load. Tropospheric sulfur is quickly washed out in the form of acid rain. Coal stack sulfur emissions are mostly a regional problem. Evidence for this is the fact that the US EPA shows a consistent drop in US sulfur dioxide measurements since around 1980. The Chinese coal emissions aren’t pushing up SO2 levels in America’s skies. The EPA measurements are made near the ground, so they can miss stratospheric concentrations. Still, the stratospheric component will contribute to near ground level measurements as it drifts down. It would be interesting to attempt to infer the global loading by looking at near ground measurements and perhaps acid rain data. Unless I’m missing something, if we don’t see elevated sulfur levels here, the cooling effect must be largely a regional, not global, effect just from physical considerations. Further, as the IPCC in earlier reports classed our understanding of the effect of sulfur compounds on climate as ‘poor.’ Simply because volcanic sulfur emissions in the stratosphere are effective at cooling the climate, it doesn’t follow that we understand tropospheric emissions enough to be sure the paper’s model is in fact correct.
Speaking of models, as is so common in the climate papers, we have models used to predict both the SO2 cooling contribution, and more importantly, models that predict the warming from CO2 forcings, solar cycle forcings, and ENSO forcings. The authors conclude that their model shows the declining solar insolation of the Sun’s solar cycle, plus La Niña cooling, along with SO2 aerosols just balance out the CO2 warming effect from about 1998 to 2002 and have a small net cooling effect thereafter till 2008. Add it up and all the manmade warming and cooling effects just about cancel out, leading to no warming, and neatly explaining the lack of increasing global temps during the late Nineties and the Oughties (1998-2008). But there are other effects from burning coal besides higher sulfur emissions. As Chinese sulfur emissions rise, so do soot (black carbon) emissions, which tend to warm the air, and which the paper sort of glosses over by lumping the black carbon effects with stratospheric water vapor (which are deemed to be warming neutral, despite other research claims to the contrary). I don’t understand how the authors lump together stratospheric water vapor and tropospheric black carbon, nor how they simply dismiss their effects.
This is all a nice just-so story, and it may even be true. But I am skeptical of any climate result that comes strictly from models and not actual physical measurements that have real error bars. My main concern is that what the authors do is compare one set of models with another set of models. That is fine as far as it goes, but the map is not the territory. Models are simplifications. Models omit details, sometimes intentionally and sometimes unintentionally. And those details can be very important. In fact, if the authors are correct, the detail of SO2 emissions that was omitted from earlier climate model behaviors was just such an important detail! There is a 2005 paper that points out this very behavior, so perhaps we do have a ‘prediction’ which was not considered significant at that time. What other important details are missing from the models? Inquiring minds want to know!
I’m withholding judgement on this till others look to see how all this should play out. In particular, since I like to see physical predictions used to validate model conclusions, I’m looking for a regional climate signal due to the regional nature of the SO2 increase. In fact, if coal-fired power plant stack emissions are so effective at cooling, we should expect to see a warming effect in the US as our sulfur levels have dropped. But if anything, the US regional climate has been cooling faster than the global results. This seems counterintuitive, if the mechanism in the paper is indeed the correct explanation for global temps.
We should know more once real specialists have a chance to study the paper.
 I’ve used the WUWT link as the Proceedings of the National Academy of Sciences full text version is behind a paywall.
Posted by Fred on July 11, 2011
When I asked Oxburgh if [Keith] Briffa [CRU academic] could reproduce his own results, he said in lots of cases he couldn’t,” Stringer told us. “That just isn’t science. It’s literature. If somebody can’t reproduce their own results, and nobody else can, then what is that work doing in the scientific journals?
Real Science isn’t a candidate for the Journal of Irreproducible Results.
Posted by Fred on July 9, 2011
When I first started looking at GISP2 it seemed to me that there were several places in the record that looked very much like the sharp spike in temperature we’re experiencing now. The obvious thing thing to do seems to be to overlay them for an easy comparison:
Here I’ve plotted the 400 years following each minimum in the record that leads to a sustained sharp rise. There were 10 of them; the first five are plotted in cyan and the more recent 5 in blue. You can see that in the latter part of the Holocene the traces settle down from the wilder swings of the earlier period. Even so, every curve, even the early ones, seems to have an inflection — at least a change in slope — somewhere between 200 and 250 years after the minimum.
J. Storrs Hall is a very smart guy. He has taken a good look at the historical record, not simply computer model runs. Read his post over at WUWT where he compares the modern temperature record with the Greenland ice core reconstruction for the Holocene. The ice core reconstruction gives actual climate behavior. It isn’t a computer climate model run. You can see that Gaia’s behavior isn’t unprecedented; and I we can be sure the Neanderthals weren’t driving SUVs or burning coal for electric power.
Remember, extraordinary claims require extraordinary proof. I believe our climate has been warming since the end of the Little Ice Age. I’m less convinced that CO2 is the only, or even the major, driver of that warming. And as you can see above, the warming trend is not unprecedented.
Posted by Fred on July 2, 2011