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.

Comments

Snow storm?

[number6x]

Very low rates of commenting today. Could it be the blizzard on the east coast keeping everyone busy?

Good to see it's not all robots posting here.

Back on topic, it's an interesting read. 30-50% may be natural climate trend and the rest man made (50-70%) man made.

It may be good science, but showing 50-70% man made probably won't go down well with the current administration. <sarcasm> Prepare to have the budget cut for this "U.S.-based team of scientists", unless they get their alt-facts corrected.</sarcasm>

Re: percentages

[Anonymous Coward]

People don't understand distributions. It has to either be all or nothing. If humans contribute 40% to global warming and nature contributes 60%, the majority of people will fall into "well nature is doing it too" BS, deflecting the significance of their own contribution.

I'm all for honest reporting but I don't trust trust the average US citizen for reading, interpreting, and reacting to study results--nor do I trust media outlets with agendas that could care less about the environment. I can see the Fox headlines now "Nature contributes 60% of global warming, Obama cover up to kill coal" never discussing the significance of the other 40% side of the story.

Re:Scary stuff

[tlhIngan]

Harldy anyone disputes the fact there is global warming. The dispute is over how much of it we're causing and whether or not its actually abnormal given that in the history of the planet it has been far warmer many many times over the millennia. Then there's what we should do about it and given how almost every other month something new is being found out about our climate and what affects it I hardly think we're in a position to be deliberately messing about with it. Sure reduce/eliminate what we put in the air etc but when you start doing things like schemes to reflect the sun, artificially forcing rain etc then we may find we're doing more harm than good.

ObXKCD: https://xkcd.com/1732/

If the chart is accurate, "far warmer many many times" is inaccurate - we're at the peak already and even the most harsh scenarios for reversing it will have the climate get warmer still.

Re:percentages

[quantaman]

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.

Globally almost 100% man-made is accurate because natural climate variations simply aren't that fast enough to be a big contributor.

However, local climates are more variable, particularly the Arctic, so percentages come into play. From the article it sounds like previous research simply didn't have enough data to make useful percentage estimates.

Science versus politics

[Okian Warrior]

I think you mean arguing against facts, because that's all that xkcd comic was. Which sounds exactly like something an anonymous coward would do.

As much as people like to insult and deride the other side, there are valid concerns there. The concerns are so large and looming that the "correct" side has lost a lot of credibility. I think a lot of the public is noticing the elephant in the room, and this is giving the deniers leverage in the minds of the people.

Rather than continue to insult and deride, perhaps it's time to address the credibility gaps.

Point 1: Scott Adams pointed out that when asked the question "how much of global warming is caused by humans, and how much is natural" in debates and televised interviews, no scientist had an answer. Specifically, Bill Nye, who is the global warming champion, didn't have an answer to that question.

Point 2: Another Scott Adams observation is about the models. Why is there more than 1 model? Shouldn't scientists agree on the best model and just use it? Shouldn't scientists agree on the best *data* and just use it?

Point 3: Also from Scott Adams is the observation that NO other complex model has ever had predictive value, and why should we believe that this one does?

Point4: From my view, climate change is closely tied with the actions that "we must do to save ourselves!", and those actions are always a) part of the liberal agenda, b) involve reducing our standard of living, and c) negatively impact most people while further lining the pockets of the rich and powerful.

Nowhere do we see proposals that make more electricity available to more people, nowhere does anyone point out that 85% of all resources are used by industry (therefore reducing home electricity consumption is less effective), no one proposes solutions for a decentralized grid, or reducing consumption by giving everyone fast internet access (doing things online generally uses much fewer resources than in person), or changing tax rules to promote telecommuting, or any of a hundred other easy changes that would make our lives better while being more efficient. It's always about enduring more hardship.

Point5: From my view, the "correct side" has lost a lot of credibility simply by their actions over the last 3 months.

If "that side" will riot over the outcome of a fair election, headline unsubstantiated lies, leak secret information for political assassination, call for literal assassination, how is it that they have any credibility over other issues?

Leonardo DiCaprio flies an eyebrow artist 7,000 miles to do his eyebrows, and we're supposed to believe him about global warming?

It's not that I don't believe in the science behind global warming, I do.

I just don't believe in the politics of global warming, that's all.

Re:Science versus politics

[Immerman]

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