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Arctic Ice Loss Driven By Natural Swings, Not Just Mankind, Says Study (reuters.com)
Alister Doyle, reporting for Reuters: Natural swings in the Arctic climate have caused up to half the precipitous losses of sea ice around the North Pole in recent decades, with the rest driven by man-made global warming, scientists said on Monday. The study indicates that an ice-free Arctic Ocean, often feared to be just years away, in one of the starkest signs of man-made global warming, could be delayed if nature swings back to a cooler mode. Natural variations in the Arctic climate "may be responsible for about 30-50 percent of the overall decline in September sea ice since 1979," the U.S.-based team of scientists wrote in the journal Nature Climate Change. Sea ice has shrunk steadily and hit a record low in September 2012 -- late summer in the Arctic -- in satellite records dating back to 1979. The ice is now around the smallest for mid-March, rivaling winter lows set in 2016 and 2015. The study, separating man-made from natural influences in the Arctic atmospheric circulation, said that a decades-long natural warming of the Arctic climate might be tied to shifts as far away as the tropical Pacific Ocean.
Just a bad summary... this article is better: https://www.sciencedaily.com/r...
"Anthropogenic forcing is still dominant -- it's still the key player," said first author Qinghua Ding, a climate scientist at the University of California Santa Barbara who holds an affiliate position at the UW, where he began the work as a research scientist in the UW's Applied Physics Laboratory. "But we found that natural variability has helped to accelerate this melting, especially over the past 20 years." ...
"In the long term, say 50 to 100 years, the natural internal variability will be overwhelmed by increasing greenhouse gases," Ding said. "But to predict what will happen in the next few decades, we need to understand both parts."
Finally a study that shows percentages.The politicals have have claimed that climate change is either 100% man-made or 100% natural, depending upon which side of the argument they were on. Reasonable people knew that it had to be a bit of both, but there never seemed to be any studies that showed what the percentages of each it was.
Ol' Rick Dawson had a farm EIEIO
Read the article...
30-50% of the warming is due to natural, not man made, effects.
Or, as scientists have been saying for decades, the majority of the warming (50 - 70%) is due to man made effects.
This includes scientists at shell oil and Exxon-Mobil. I remember debate class in high school, fall of 1979, our team was 'pro' nuclear power. We used research from oil companies about the dangers of global warming as one one the arguments in favor of expanding nuclear power use. We won the debate, despite the fact that the 3 mile island accident happened in spring of '79. That made it a very tough debate to win the pro nuclear side of the argument.
The article doesn't need to prove anything, other than cite the study, because it isn't science. It is just news about the science. I am sure that the study itself, which was made by scientists and published in a scientific journal, would actually show their workings; otherwise they would not get published. But the fact that we haven't seen the study is not itself evidence that the figures were based on "no science what-so-ever".
If you walk into a room with your eyes closed, you cannot definitively say that there isn't a red ball in the room. All you can say is that you can't see a red ball. Similarly, if you haven't read the paper, you can't say that the percentages are unproven. All you can say is that you haven't seen the proof.
Should the original poster have read the study before discussing the percentages? If this were an academic discussion or an official policy document then absolutely. But this is just a forum on the internet, occupied by deniers who make no effort to prove their own claims. Regurgitating figures from the article is a step up for a lot of people around here who never get past reading the headlines.
If all you've heard is "we need to lower everyone's quality of life", then I suspect you've been listening primarily to sources contributing to the smear campaign, because I've heard a great deal of things along the lines of "let's promote transitioning to other energy sources" and "Let's move government subsidies from fossil fuels to emerging alternatives".
The science of anthropogenic global warming itself is actually quite simple - adding more insulation slows heat loss, and the planet has to get hotter until it resumes radiating heat as fast as it's getting it from the sun.
Crude back of the napkin calculations ignoring all subtleties and knock-on effects (the vast majority of which will make things worse): water vapor and CO2 combined are responsible for the vast majority of the greenhouse effect. There's about 10x as much water vapor in the atmosphere as CO2, so assuming both molecules are similarly potent infrared scatterers, CO2 is responsible for about 10% of the total planetary insulation. Human activity since the industrial revolution is clearly responsible for about 25% of the CO2 in the atmosphere, meaning we've increased total planetary insulation by about 2.5%. To restore the energy balance, the planet must therefore radiate about 2.5% more energy. Thermal radiation increases with the 4th power of temperature, so we can therefore expect planetary temperature to increase by a factor of (1.025)^(1/4) = 1.0062, or 0.62%. Current average temperature of the planet is 289K, so that translates to an increase of 1.8C, or 3.2*F, possibly not enough to be devastating on it's own, but quite sufficient to potentially allow normal variability to push things past a tipping point so that the planet transitions back to a tropical/desert state, probably killing most life in the process (a warm Earth is potentially more hospitable, but the transition periods have generally not been kind). And of course that's also only the expected change if we managed to completely halt the increase of CO2 today, which is all but impossible.
Where the model gets complicated is trying to make it predictive in the face of a chaotic system - there's *lots* of different forces in play, and to actually become meaningfully predictive you have to take into consideration at least the overwhelming majority (by effect weight). You don't need any of that to know that "doing X is going to be very bad", but you *do* need it if it's clear that "doing X" will continue despite your warnings, and you want to be able to predict what exactly "very bad" is likely to mean so that you can start preparing for it.
Basically, most of the climate science for the last few decades or so has had little to do with proving human responsibility - that was already done many decades ago and the observations are continuing to support those crude predictions relatively well. Current research is trying to make the model usefully predictive so that we can pinpoint where exactly the tipping point is (have we passed it already? Is there realistic hope for avoiding it?), as well as giving us as much warning as possible as to what we need to prepare for.
For example, over a decade ago I attended a talk by a group who had run by far the most detailed simulation of expected climate change effects in California over the next few decades - which predicted that within ~30 (50? I forget) years California would no longer have any substantial snow pack, meaning their water would come almost entirely as floods. Their recommendation was to start building dams immediately since due to the engineering and political challenges, dams have an expected 20+ year lag between when the decision to build them is made, and when they're actually completed. Got to start the process today if you want to have them finished in time to be useful. Thus far, their predictions seem to be holding up fairly well.
As for DiCaprio's hygiene choices - so he's a hypocrite, so what? So am I for that matter, though I don't have the resources to be nearly so excessive
--- Most topics have many sides worth arguing, allow me to take one opposite you.
This is not the paper described in the summary, but rather an older paper with some of the same authors. The paper referenced in the summary was published online yesterday in Nature Climate Change. I'm sorry that I can't give a direct link to a .pdf (yay for paywalls keeping all of the non-ivory tower plebs out! huzzah!), but for those with access, the paper can be found at Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice. For those without access to an academic library, the first author provides an email contact. One presumes that a polite request would yield the full text of the paper.
Rhapsody in Numbers