o.m. raspopov (1), v.a. dergachev (2),
DESCRIPTION
LONG-TERM SOLAR ACTIVITY VARIATIONS AS A STIMULATOR OF SHARP CLIMATE CHANGES. O.M. Raspopov (1), V.A. Dergachev (2),. - PowerPoint PPT PresentationTRANSCRIPT
(1) St.Petersburg Branch (Filial) of Pushkov Institute of Terrestrial Magnetism, Ionosphere, and
Radiowaves Propagation of RAS, St.-Petersburg, Russia, [email protected]
(2) Ioffe Physico-Technical Institute of RAS, St.Petersburg, Russia.
O.M. Raspopov (1), V.A. Dergachev (2),
LONG-TERM SOLAR ACTIVITY VARIATIONS AS A STIMULATOR OF
SHARP CLIMATE CHANGES
International Conference “50 years of International Geophysical Year andElectronic Geophysical Year”, 16-19 September, 2007, Suzdal, Russia
It is known that deep solar activity minima are accompanied by sharp climate changes. For example, the Maunder minimum of solar activity (1645-1715) stimulated the beginning of the Little Ice Age.
Goal of the presentation:to give experimental evidence that not only deep solar activity minima, but also a high solar activity level can lead to sharp global climate changes through stimulation of dynamic processes at the Earth’s surface.
Long-term cyclicity of solar Long-term cyclicity of solar activityactivity
● ● 11-11-year cycle of sunspot numbersyear cycle of sunspot numbers ((Schwabe)Schwabe)
● ● 22-23-year cycle of solar magnetic 22-23-year cycle of solar magnetic polarity changespolarity changes ( (Hale)Hale)
● ● 80-90-year cycle of amplitude 80-90-year cycle of amplitude modulation of 11-year cycles modulation of 11-year cycles ((Gleissberg)Gleissberg)
●● 180180--230-230-year cycleyear cycle ( (~~210-210-year - year - deVries)deVries)
● ● 2300-2400-year cycle2300-2400-year cycle ( (Hallstattzeit)Hallstattzeit)
Record of variations of sunspot numbers W.
Evidence of 11- , 22-23-, and 80-90 year solar activity
variations
80-90 year cycle
22-23 year cycle
11-year cycle
Relation between variations of Relation between variations of sunspot numbers W and sunspot numbers W and variations of galactic cosmic variations of galactic cosmic ray fluxesray fluxes
1010BeBe
Recording of cosmic rays and Recording of cosmic rays and cosmogenic isotopes generationcosmogenic isotopes generation
Atmosphere10Be
Galactic cosmic rays
14C
Earth surface
14СО2
Neutron monitor
Variations of 14C concentration in tree-ringsand the Earth’s magnetic dipole moment
during the Holocene
Geomagneticdipole
Maunderminimum
Homericminimum
~5200-5400 years minimum
~7200 years minimum
The Holocene
Maunderminimum
Homericminimum
~5200-5400 years minimum
~7200 years minimum
Low solar activity
High solar activity
Δ14C
Variations of 14C concentration in tree-ringsand the Earth’s magnetic dipole moment during the Holocene
Variations of 14C concentration relating tosolar activity
2300-2400 yearvariations of 14C concentration
High solar activity
The Holocene
Low solar activity
Variations of aerosols inGreenland ice2300-2400 year cyclicityin atmospheric circulation
Global glaciers extension
Swiss alpine glaciersretreat
2300-2400 year solarcyclicity (Δ14C variationsfiltered in 2000-3000 yearperiod range)
Long-term solar activity variations and climate change during the Holocene
Changes in high-latitude timber line location in Scandinavia and Canada
Changes in high-latitude timber line location in Finnish Lapland
Reconstructed summer temperature changes in Finnish Lapland
Changes in high-latitude timber line location in northern Sweden
Number of dated subfossiltrees collected in northernFinnish Lapland
Changes in high-latitude timber line location in northern Canada
Reconstructed summer temperature changes in northern CanadaTimber line change in Scandinavia and Canada shows cold time
intervals similar to glacier expansion time intervals
What could be reason for sharp cooling events during the high solar activity time intervals?
Possible reason: ice-rafting events in the North Atlanticduring Ice Age and the Holocene developed during warmclimate condition (high solar activity)
Ice-rafting event abruptly change the North Atlantic overturning circulationand displace the position of northern edge of the Gulfstream to the South and develop of sharp climatic cooling.
Ice-rafting events during the Holocene [Bond et al. 2002]
12 3
4 566
7
Changes of solar activity and ice-rafting events during the Holocene
High solar activity
Solar activity (Δ14C)
Low solar activity
Ice-raftingevents(IRE)
Grand solaractivityminima
Beginning of IRE correlate well with time intervals of high solar activity and sharp climate changes
Sharp climate changes during the Pleistocene:Dangard-Oeschger and Henrich events
Solar activity (10Be), temperature changes, and ice-rafting eventsdevelopment over the past 40 ky in the North Atlantic region
Solar activity
Temperature changes
Ice-raftingevents
Sharp climatechanges correlate wellwith solaractivity variations anddevelopment of ice-raftingevents
ConclusionThe influence of long-term solar activity variations on climatic parameters at time scales from 40,000 to 10,000 years ago (the Pleistocene) and frommodern period to 10,000 years ago (the Holocene) has been analyzed. Comparative analysis of temperature oscillations and solar activity variations (variations in the concentration of cosmogenic 10Be isotopes in Greenland ice and 14C isotopes in tree rings) has revealed the solar influences on climate oftwo kinds. On the one hand, deep solar activity minima create conditions for sharp climate changes with the 2,400-2,300-year periodicity that manifest themselves in the most pronounced way during the Holocene. On the other hand, a high solar activity level and, hence, a high level of solar irradiance gives rise to dynamic processes at the Earth’s surface, such as ice-rafting events in the North Atlantic. Computer simulation has shown that these ice-rafting events can be caused by an increase in the surface ocean temperature, i.e., the condition created by high solar activity and solar irradiance levels. Ice-rafting events sharply change the character of the North Atlantic overturning circulation (NAOC), thus displacing the Northern edge of the Gulf Stream southwards, which leads to sharp climate changes of the global nature. Analysis of the experimental data has shown that a high solar activity level was responsible for development of ice-rafting events during both the Pleistocene and Holocene. Therefore, it can be concluded that both deep solar activity minima and a high solar activity level can create conditions for sharp climate changes.
ConclusionПроведен анализ воздействия долговременных вариаций солнечной активности на климатические параметры на временных шкалах от 40000 до 10000 лет назад (плейстоцен) и от современной эпохи до 10000 лет назад (голоцен). Сравнительный анализ температурных изменений и вариаций солнечной активности (вариации содержания космогенных изотопов 10Be в гренландском льду и 14C в кольцах деревьев) выявил двоякого рода солнечное воздействие на климатические изменения. С одной стороны, глубокие минимумы солнечной активности создают условия для резких климатических изменений, проявлявшихся особенно четко в голоцене с 2400-2300-летней периодичностью. С другой стороны, высокий уровень солнечной активности и, следовательно, солнечной иррадиации создают условия для развития процессов на земной поверхности, аименно, массового сброса ледниковых масс в Северную Атлантику (ice-rafting events). Результаты моделирования свидетельствуют, что подобные сбросы ледяных масс могут быть стимулированы повышением поверхностной океанической температуры, т.е. условиями, создаваемыми высокой солнечной активностью и высоким уровнем солнечной иррадиации. Ice-rafting events резко изменяют характер North Atlantic overturning circulation (NAOC), отодвигая северную оконечность Гольфстрима к югу, что приводит к резким климатическим изменениям глобального характера. Проанализированные экспериментальные данные свидетельствуют, что высокий уровень солнечной активности стимулировал развитие ice-rafting events как в плейстоцене, так и в голоцене. Таким образом, как глубокие минимумы солнечной активности, так и высокий уровень солнечной активности могут создавать условия для развития резких климатических изменений.