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地球は2030年からミニ氷河期に入るのか？
2015年7月22日（水）堀田 佳男
2030年頃から地球はミニ氷河期に突入する――。
英ウェールズで7月9日に開かれた王立天文学会で英国の研究者が驚くべき発表をした。今後15年ほどで太陽の活動が60％も減衰するというのだ。英テレグラフ紙を含めたメディアは「ミニ氷河期に突入」というタイトルで記事を打った。
氷河期と言えば、一般的には地球が長期間にわたって氷に閉ざされるイメージがある。海や運河が氷床に被われて、人間や動物の生活に大きな支障をきたす印象がある。
研究発表をしたのは英ノーザンブリアン大学のヴァレンティナ・ジャルコヴァ教授。太陽の内部にある磁場の変化によってミニ氷河期が訪れる可能性を示唆した。
同教授によれば、太陽内に2つの異なる磁気波があることを発見。2波は周波数が異なるが、両波ともに11年周期で変化するという。ジャルコヴァ教授は両波を基に太陽活動の動きを探る新しいモデルを確立した。精度は97％だという。
これまで太陽の活動を探るには、黒点の数を調査する方法が一般的だった。黒点周辺で爆発現象が多く起こるため、黒点が多いと太陽の活動は活発になる。
天文学者の間では、1755年に始まる太陽活動を第1太陽周期とする黒点調査が一般的だ。現在は第25太陽周期に入っているとされる。ただ周期の長さは10年から12年でばらつきがあり、変動を的確に説明するには多少の無理があったとされる。
英テムズ川が再び完全に凍結する？
ジャルコヴァ教授は新モデルを使い、2030年に始まる第26太陽周期で、太陽の活動が著しく低下することを予測。記者会見で次のように説明した。「第26太陽周期で、2つの磁気波はまるで鏡に映されたように相殺しあい、（地球は）『マウンダー極小期』のような状況になると推測できる」。
「マウンダー極小期」は1645年から1715年まで続いたミニ氷河期で、黒点の数が著しく減少したことで知られる。地球では寒冷化が進んだ。黒点を研究した天文学者エドワード・マウンダーにちなんで「マウンダー極小期」と呼ばれている。
この時期は、英テムズ川が完全に凍結したことでも知られる。米ニューヨーク市ではニューヨーク湾が凍って自由の女神やスタッテン島まで歩いていけた。またアイスランドは周囲が海氷に閉ざされたため、貿易や漁業に大きな被害がでた。飢饉に見舞われて人口がほぼ半分になったとの記録さえある。
こうした話を耳にすると、ミニ氷河期が日本に訪れた時のインパクトも計り知れない気がしてくる。
ミニ氷河期の到来を断言はできない
ジャルコヴァ教授はメディアの報道に驚きを隠さない。世界中のメディアが「ミニ氷河期が来る」といったトーンで報道したことに戸惑い、後日、「気候変動には言及していません」と述べた。
ただ「（気候に）変化があるという予測にはたぶん同意しなくてはいけないでしょう」とも述べており、教授の発言には矛盾を感じないでもない。学者として研究内容を数値で示すことはできても、15年後に地球規模で寒冷化現象が起こるかどうかは断言しづらいということだろう。
イヌイットに伝わる氷河期の周期
筆者は氷河期について、過去に興味深い話を聞いている。米アラスカ州北端に位置するポイントバローという町でイヌイット（先住民族）を取材した時のことだ。
生存捕鯨を行うためにカヌーで北極海にこぎ出していた男性は、なんら迷った様子を示すこともなく氷河期について話をした。
「イヌイットの間では、氷河期の周期は5万年と言われている。最後の氷河期が終わってからすでに1万年以上が経っているから、現在は間氷期だ。地球温暖化の話がでているが、間氷期だから地球の気温が上昇するのは当たり前だろう。あと数万年経てばまた氷河期がやってくる」
イヌイットは民間伝承という形で、過去の出来事や史実を子孫に口頭で伝える文化をもつ。アザラシの毛皮を着たこの男性は、5万年という氷河期の周期について「間違ってはいないはずだ」と自信をもって語った。
氷河期には数万年の短期的なサイクルのものと、5億年ほどの長期的なサイクルのものに分類できるようだ。長期サイクルを見れば、地球が誕生して以来、氷河期は4回あった。最古の氷河期は24億年も前だと言われる。
短期サイクルを見れば、過去300万年の間、氷河期が終わって次の氷河期が来るまでに4万〜10万年の年月がかかっている。科学の世界ではすでに、地表の調査などから過去の氷河期が特定されており、イヌイットの伝承として聞いた「5万年」という周期は大きくは外れていないことがわかっている。
ジャルコヴァ教授の論文とは反対の説もあり
氷河期が到来する要因はいくつもあると言われる。原生代後期の氷河期は大気中の二酸化炭素の減少で始まり、増加で終わったようだ。また大陸の移動によって海流に変化が生まれたことも要因の1つとされる。さらにヒマラヤ山脈の隆起が大気の環流を変化させ寒冷化を進めたとも考えられている。
今回、注目されているミニ氷河期は二酸化炭素の増減や大陸移動より、太陽の変動によって起きるという報告がある。
ミニ氷河期が本当にくるのかどうかは不確かなところだ。米ワシントンポスト紙は14日、ジャルコヴァ教授の論文は査読されていないと指摘した。査読は、同じ分野の専門家から評価やチェックを受けるシステムで、学術論文を学会誌などに掲載する時には必ず経るプロセスである。
さらに「IFLサイエンス」という科学誌は「ミニ氷河期は15年後にはたぶん来ない」というタイトルの記事を、ジャルコヴァ教授の論文が発表された直後に掲載した。寒冷化を心配するよりも、二酸化炭素の増加がもたらす温暖化の方が深刻であるとの論点だ。
果たしてミニ氷河期は来るのか？
2030年になった時、「ミニ氷河期が本当に来た」ということになるのか、それとも「ハズレでした」ということになるかはわからない。実は同じような予測が2009年にも出ていた。だが「ミニ氷河期」は訪れなかった。
2009年の騒ぎは、ベルギーにある太陽黒点データセンターの予測が基礎になっていた。黒点の多さを示す相対数が2008年の2.9から、2009年4月には1.2に減少した。過去100年を眺めると、最低だった1913年の1.4によりも低い値で、ミニ氷河期がすぐにも到来すると噂された。
朝日新聞も2009年6月、「弱る太陽 活動200年ぶりの低水準」というタイトルの記事を掲載。「このままだとミニ氷河期に入る可能性がある」という研究者の予測を載せた。だがミニ氷河期は来なかったどころか、一般市民の脳裏からもすぐに消えた。
今後15年が経ち、テムズ川が再び凍結したりニューヨーク湾が凍りついたりする事態になるかどうかは、現段階では「誰にもわからない」というのが正確なところだろう。
個人的には、ニューヨーク湾が凍結してマンハッタン島から自由の女神まで歩いてみたいとも思うのだが、、、
http://business.nikkeibp.co.jp/atcl/report/15/246942/072100003
There Probably Won't Be A “Mini Ice Age” In 15 Years
July 14, 2015 | by Caroline Reid
photo credit: Wintery scene of shivering man in snowstorm or ice storm. Pepgooner/Shutterstock.
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Since our article yesterday about how reduced solar activity could lead to the next little ice age, IFLScience has spoken to the researcher who started the furor: Valentina Zharkova. She announced the findings from her team's research on solar activity last week at the Royal Astronomical Society. She noted that her team didn't realize how much of an impact their research would have on the media, and that it was journalists (including ourselves) who picked up on the possible impact on the climate. However, Zharkova says that this is not a reason to dismiss this research or the predictions about the environment.
“We didn't mention anything about the weather change, but I would have to agree that possibly you can expect it,” she informed IFLScience.
The future predicted activity of the Sun has been likened to the Maunder Minimum. This was a period when the Sun entered an especially inactive period, producing fewer sunspots than usual. This minimum happened at the same time that conditions in Northern America and Europe went unusually icy and cold, a period of time known as the “little ice age.”
The previous Maunder Minimum occurred in the 17th century and lasted between 50 and 60 years. During this time, winters were colder: for example the River Thames, which usually flows through London, notoriously froze over. The ice was so thick that people could walk from one side to the other. However, the citizens that lived in freezing, 17th century Europe survived these cold winters, and they didn't have the heating technology that we are fortunate enough to have today. If the next solar activity minimum does affect the weather on Earth, it will not be deadly for the human race.
Zharkova compared the Maunder Minimum with the one that her team predicted to occur around 15 years into the future. The next minimum will likely be a little bit shorter than the one in the 17th century, only lasting a maximum of three solar cycles (around 30 years).
The conditions during this next predicted minimum will still be chilly: “It will be cold, but it will not be this ice age when everything is freezing like in the Hollywood films,” Zharkova chuckled.
The predictions that Zharkova announced came from a mathematical program that analyzed data from the Sun. The team decided that they wanted to monitor the Sun's background magnetic field (which governs solar features like sunspots). You can see the team's data for cycles 21?23 published in The Astrophysical Journal.
After analyzing the solar data with their model, Zharkova's team noticed something that no one had ever expected before: that the Sun produces the magnetic waves in pairs. Previously everyone had thought that there was only a single source of magnetic waves in the Sun, but the evidence suggested two sources. The team used these observations to predict how the Sun's magnetic field would change in the future. “This is where we predicted this new Maunder minima,” Zharkova added.
She commented on how the changes in the Sun are likely to affect the Earth's environment. “During the minimum, the intensity of solar radiation will be reduced dramatically. So we will have less heat coming into the atmosphere, which will reduce the temperature.”
However, Zharkova ends with a word of warning: not about the cold but about humanity's attitude toward the environment during the minimum. We must not ignore the effects of global warming and assume that it isn't happening. “The Sun buys us time to stop these carbon emissions,” Zharkova says. The next minimum might give the Earth a chance to reduce adverse effects from global warming.
http://www.iflscience.com/environment/mini-ice-age-not-reason-ignore-global-warming
Thanks To Reduced Solar Activity, We Could Be Heading For A Mini Ice Age In 2030
July 13, 2015 | by Caroline Reid
photo credit: Ice As A Blanket. Pierre/Flickr (CC BY 2.0)
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Life on Earth has always been dependent on the conditions of the Sun, so scientists spend a lot of time studying its activity. A recent announcement from solar scientists suggests that the Sun may soon enter a period of significant reduced activity, possibly causing a mini ice age by 2030 ? just 15 years from now.
These predictions were announced at the National Astronomy Meeting in Llandudno, Wales, so it hasn't been possible to evaluate the research yet. However, Professor Valentina Zharkova from the University of Northumbria who made this announcement claims that the findings come from a computer model of sunspots that has made "unprecedentedly accurate predictions," as reported in The Telegraph.
The model has shown to have a 97% accuracy when mapping the past movements of sunspots, using data of solar cycles from 1976 to 2008. And if this reliability continues, then the model also has some alarming predictions for the future: a mini ice age sometime around the 2030s.
To achieve these findings, the scientists mapped the movement of solar fluid that moves in roughly 11-year cycles, which correspond to weather cycles on Earth. Around the year 2022 (labeled cycle 25), a pair of waves will be moving to the Northern and Southern Hemispheres of the Sun, getting slowly out of synch and reducing solar activity ? and thus our warm weather.
"In cycle 26, the two waves exactly mirror each other ? peaking at the same time but in opposite hemispheres of the Sun. Their interaction will be disruptive, or they will nearly cancel each other. We predict that this will lead to the properties of a 'Maunder minimum'," said Zharkova.
The Maunder minimum was a 70-year period between 1645 and 1715. The Sun produced barely any sunspots and the Earth experienced a mini ice age. Parts of northern Europe and the United States experienced uncharacteristically cold winters. The river Thames, flowing through London, even froze over for seven weeks and was passable by foot. The surface was so stable that residents could even hold 'frost fairs' on the ice.
source: imgur.com
Sunspots are relatively 'cool' regions on the Sun that appear darker when photographed. They are cooler than the rest of the Sun, but they are still around 4500 K (4200oC, 7600oF). They are caused by a concentration of intense, magnetic field from the Sun. This inhibits and redirects the flow of hot matter to that region and makes it darker ? what we call a sunspot.
Sunspots last between 1 to 100 days, during which they rotate around the Sun, following the flow of solar fluid. Sunspots go through cycles of intensity and sparsity based on the motion of the fluid cycles. There are two main waves that are slightly offset over time, producing periods of maximum and minimum solar activity.
"Effectively, when the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity," Zharkova said.
"When they are out of phase, we have solar minimums. When there is full phase separation, we have the conditions last seen during the Maunder minimum, 370 years ago."
Central Image: We generally associate a 'spot' with a small feature. However, this sunspot is 20 times the size of Earth. This one would have been visible to the naked eye - but you should never look at the Sun with unprotected eyes! NASA.
Main Image: Pierre/Flickr
[H/T: The Telegraph]
Note: We have written a follow-up article: There Probably Won't Be A “Mini Ice Age” In 15 Years
Read this next: Japan Accepts Giant Robot Fight Challenge From America
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http://www.iflscience.com/environment/we-could-be-heading-mini-ice-age-2030
Media Reports The World Will Enter A ‘Mini Ice Age’ In The 2030s. The Reverse Is True.
BY JOE ROMM JUL 13, 2015 4:00PM
CREDIT: SHUTTERSTOCK
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U.K. tabloids, conservative media, and others are (mis)reporting that the Earth will enter a “mini ice age” in the 2030s. In fact, not only is the story wrong, the reverse is actually true.
The Earth is headed toward an imminent speed-up in global warming, as many recent studies have made clear, like this June study by NOAA. Indeed, a March study, entitled “Near-term acceleration in the rate of temperature change,” makes clear that a stunning acceleration in the rate of global warming is around the corner ? with Arctic warming rising 1°F per decade by the 2020s!
Also, right now, we appear to be in the midst of a long-awaited jump in global temperatures. Not only was 2014 the hottest year on record, but 2015 is in the process of blowing that record away. On top of that, models say a massive El Nino is growing, as USA Today reported last week. Since El Ninos tend to set the record for the hottest years (since the regional warming adds to the underlying global warming trend), if 2015/2016 does see a super El Nino then next year may well crush the record this year sets.
Whatever near-term jump we see in the global temperatures is thus likely to be followed by an accelerating global warming trend ? one that would utterly overwhelm any natural variations such as a temporary reduction in solar intensity. A recent study concluded that “any reduction in global mean near-surface temperature due to a future decline in solar activity is likely to be a small fraction of projected anthropogenic warming.”
That’s true even for one as big as the Maunder Minimum, which was linked to the so-called Little Ice Age.
The “Little Ice Age” is a term used to cover what appears to have been two or three periods of modest cooling in the northern hemisphere between 1550 and 1850.
I know you are shocked, shocked to learn that unreliable climate stories appear in U.K. tabloids, the conservative media, and those who cite them without actually talking to leading climate scientists. Often there is a half truth underlying such stories, but in this case it is more like a nano-truth.
Last week, in Llandudno, north Wales, the Royal Astronomical Society (RAS) held Cyfarfod Seryddiaeth Cenedlaethol 2015 ? the “National Astronomy Meeting 2015″ (in case you don’t speak Welsh). An RAS news release had this startling headline, “Irregular Heartbeat Of The Sun Driven By Double Dynamo.”
Okay, that wasn’t the startling part. This was: “Predictions from the model suggest that solar activity will fall by 60 per cent during the 2030s to conditions last seen during the ‘mini ice age’ that began in 1645.”
Sunspot_Numbers WikipediaCREDIT: WIKIPEDIA
Ah, but the word choice was confusing. We’re not going to have temperature “conditions” last seen during the Little Ice Age. If this one study does turn out to be right, we’d see solar conditions equivalent to the Maunder Minimum in the 2030s.
This won’t cause the world to enter a mini ice age ? for three reasons:
The Little Ice Age turns out to have been quite little.
What cooling there was probably was driven more by volcanoes than the Maunder Minimum.
The warming effect from global greenhouse gases will overwhelm any reduction in solar forcing, even more so by the 2030s.
So how little was the Little Ice Age?
The most comprehensive reconstruction of the temperature of the past 2000 years done so far, the “PAGES 2k project,” concluded that “there were no globally synchronous multi-decadal hot or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age.”
PAGES 2k Green dots show the 30-year average of the new PAGES 2k reconstruction. The red curve shows the global mean temperature, according HadCRUT4 data from 1850 onwards. In blue is the original hockey stick of Mann, Bradley and Hughes (1999 ) with its uncertainty range (light blue). Graph by Klaus Bitterman.
The Little Ice Age was little in duration and in geographic extent. It was an “Age” the way Pluto is a planet.
Writing on Climate Progress, climatologist Stefan Rahmstorf noted the researchers “identify some shorter intervals where extremely cold conditions coincide with major volcanic eruptions and/or solar minima (as already known from previous studies).”
That brings us to the second point: The latest research finds that what short-term cooling there was during the Little Ice Age was mostly due to volcanoes, not the solar minimum. As “Scientific American” explained in its 2012 piece on the LIA, “New simulations show that several large, closely spaced eruptions (and not decreased solar radiation) could have cooled the Northern Hemisphere enough to spark sea-ice growth and a subsequent feedback loop.” The period associated with the LIA “coincide with two of the most volcanically active half centuries in the past millennium, according to the researchers.”
The cooling effect from the drop in solar activity during even a Maunder Minimum is quite modest. Environmental scientist Dana Nuccitelli discussed the literature underscoring that point in a U.K. Guardian post from the summer of 2013, the last time the “Maunder Minimum” issue popped up.
That brings us to the third point: Whatever cooling the Little Ice Age saw as result of the Maunder Minimum, it pales in comparison to the warming we are already experiencing ? let alone the accelerated warming projected by multiple studies. That’s clear even in Pages 2k reconstruction above.
Just last month “Nature Communications” published a study called, “Regional climate impacts of a possible future grand solar minimum.” This found that, “any reduction in global mean near-surface temperature due to a future decline in solar activity is likely to be a small fraction of projected anthropogenic warming.” As with the Little Ice Age, any significant effects are likely to be regional in nature ? and, of course, temporary, since a grand solar minimum typically lasts only decades.
So, no, the Daily Mail is quite wrong when it trumpets, “Scientists warn the sun will ‘go to sleep’ in 2030 and could cause temperatures to plummet.”
In actuality, what is going to happen in the business-as-usual emissions scenario (RCP8.5) is closer to the figure below, which plots “rate of change” of warming:
Decadal change RCP8.5Global rates of decadal temperature change over 40-year periods. Results are shown for: central climate assumptions (thick solid line), range due to uncertainty in aerosol forcing (grey shading), and range due to uncertainty in climate sensitivity (blue shading). The outer bounding cases are shown as dotted lines. The thin solid black line shows the historical rate of change using the HADCRU4 observational data. The vertical dashed line indicates 2014. Via PNNL.
In the RCP8.5 scenario, the rate of warming post-2050 becomes so fast that it is likely to be beyond adaptation for most species ? and for humans in many parts of the world, as I discussed here. The warming rate in the central case hits a stunning 1°F per decade. Arctic warming would presumably be at least 2°F per decade. And this goes on for decades.
No Maunder Minimum can save homo sapiens from that catastrophic outcome. Only humanity can ? by ignoring those who deny or mislead on climate science and instead taking aggressive action to slash carbon pollution ASAP.
http://thinkprogress.org/climate/2015/07/13/3679662/global-warming-speed-up-not-ice-age/
NOAA Study Confirms Global Warming Speed-Up Is Imminent
BY JOE ROMM JUN 5, 2015 12:03PM
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A major new study from NOAA finds more evidence that we may be witnessing the start of the long-awaited jump in global temperatures. As Ireported in April, many recent studies have found that we are about to enter an era of even more rapid global warming.
Indeed, one March study, “Near-term acceleration in the rate of temperature change,” warns the speed-up is imminent — with Arctic warming rising a stunning 1°F per decade by the 2020s.
The new study in Science from a team of NOAA scientists, “finds that the rate of global warming during the last 15 years has been as fast as or faster than that seen during the latter half of the 20th Century,” as NOAA explains.
The director of NOAA’s National Centers for Environmental Information, Thomas Karl, told the UK Guardian that “considering all the short-term factors identified by the scientific community that acted to slow the rate of global warming over the past two decades (volcanoes, ocean heat uptake, solar decreases, predominance of La Niñas, etc.) it is likely the temperature increase would have accelerated in comparison to the late 20th Century increases.”
What happens when these various temporary factors stop? Karl explained: “Once these factors play out, and they may have already, global temperatures could rise more rapidly than what we have seen so far.”
In other words, the long-awaited jump is global temperatures is likely imminent. How big is the jump? As I reported in April, top climatologist Kevin Trenberth has said it would be as much as 0.5°F. Given that 2015 is crushing itfor the hottest year on record, we appear to be already witnessing a big piece of that jump.
NOAA’s new study not only incorporates the latest global temperature data from 2013 and 2014. Their “calculations also use improved versions of both sea surface temperature and land surface air temperature datasets” (detailedhere). The result, as NOAA explains, is that the new “study refutes the notion that there has been a slowdown or ‘hiatus’ in the rate of global warming in recent years.” In particular, the authors conclude bluntly:
Indeed, based on our new analysis, the IPCC’s statement of two years ago – that the global surface temperature “has shown a much smaller increasing linear trend over the past 15 years than over the past 30 to 60 years” – is no longer valid.
Turns out the “long-term global warming trend” — which is redundant because the global warming trend was always a long-term phenomenon — has remained constant. But then CP readers already knew that. Back in January I reported that Dr. Gavin Schmidt, director of NASA’s Goddard Institute of Space Studies, tweeted, “Is there evidence that there is a significant change of trend from 1998? (Spoiler: No.)” He posted this chart:
NASA temperature data dispel the myth of a recent slow-down in long-term warming trend. But there was a big jump in temps during the mid-1990s. Many scientists believe we may be witnessing the start of another jump.
On Thursday, Schmidt posted on RealClimate an excellent analysis of the faux pause.
The March study mentioned earlier makes clear the only “pause” there has been was in the long-expected speed-up of global warming. The rate of surface warming should have started to accelerate in the past decade, rather than stay fairly constant.
The authors warned that, by 2020, human-caused warming will move the Earth’s climate system into a regime of rapid multi-decadal rates of warming. They project that within the next few years, “there is an increased likelihood of accelerated global warming associated with release of heat from the sub-surface ocean and a reversal of the phase of decadal variability in the Pacific Ocean.”
That appears to be happening now.
http://thinkprogress.org/climate/2015/06/05/3666286/global-warming-speed-up/
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