SOLAR VARIATION AND CLIMATIC CHANGES

By- Dr. Vinay Kumar PandeyDr. Ajai Mishra,

Dr. Shashank Shekhar Mishra

INTRODUCTION Sun covers total 99.86% mass of our solar

system and 3,33,000 times of the Earth

mass.

Earth is IIIrd planet in the solar system and

having a unique position due to life. Life

on Earth depends on energy received from

the sun.

The Sun is the source of energy that causes

the motion of the atmosphere and thereby

controls weather and climate. Any change

in the energy from the sun received at the

Earth’s surface will therefore affect

climate.

The Earth climate has always being

changing and well documented in

historical as well as geological records.

The sun has a magnetic field that flips

approximately every 11 years. Sunspots

and solar flares are caused by the

magnetic activity of the sun.

The sunspots and solar flares can affect

the earth by changing the amount of

incoming sunlight and interacting with

the earth’s magnetic field.

SUNSPOTS

OBJECTIVE

Discuss the solar variation and its effect

on Earth & climate.

Discuss the Past climate change and

solar variation

Effect of Solar Activity on Earth Climate

MEASURMENT OF SOLAR VARIATION Solar variation is the change in the amount of radiation  emitted by the Sun and in its spectral distribution

over years to millennia. These variations have periodic components, the main one being the

approximately 11-year  solar cycle. In recent decades, solar activity has been measured by satellites,

while before it was estimated using proxy variables .

Variations in total solar irradiance were too small to detect with technology available before the satellite

era, although the small fraction in ultra violet light  has recently been found to vary significantly more

than previously thought over the course of a solar cycle. Total solar output is now measured to vary (over

the last three 11-year sunspot cycles) by approximately 0.1%,or about 1.3 Watts per square meter (W/m2)

peak-to-trough from solar maximum to solar minimum during the 11-year sunspot cycle. (Weart &

Spencer, 2003)

The intensity of solar radiation reaching Earth has been relatively constant through the last 2000 years,

with variations estimated at around 0.1–0.2%. Solar variation, together with volcanic activity are

hypothesized to have contributed to climate change, for example during the Maunder Minimum

Changes in solar brightness are too weak to explain recent climate change. (Scafetta N., West B. J., 2006)

RECORD OF SOLAR ACTIVITY

Chinese observation 1000 year earlier (through loess clouds).

European telescopic observation began 1610.

14C/12C ratio is high when sunspot number is low.

Dating of tree rings demonstrates a pattern of deviations. (Merril and Mc Elhinny, 1983)

An active sun result in a strong solar wind; deflects cosmic rays and decrease 14C

production: positive 14C anomaly= cold climate (Wang et al. 1996).

Satellite observations indicate that during 11 year cycle sunspot minimum, solar

irradiance is lower (0.1%), interplanetary magnetic field weaker. (Radick,1990; Wang et

al., 1996; Willson, & Hudson 1988; Willson, et al. 1985) .

SOLAR VARIATION AND CLIMATE CHANGE

From 1645 to 1715 there were almost no sunspots. This period is called the Maunder minimum,

the peak of the Little Ice Age, a cool period affecting Europe from the 1300s to the 1800s.

(Eddy, J.A., 1981)

Data from 8000 year old bristle cone pine tree indicate 18 periods of sunspot minima in the last

7800 years. Maxima of sunspot cycle length occurred in 1770, 1845 & 1940 (Eddy, J.A., 1981).

The Dalton minimum, a 25 year span at the beginning of the 1800s when sunspots were half as

numerous as normal, corresponds to the end of the Little Ice Age.

Some people claim there is a connection between the 22 year solar cycle and the roughly 20

year drought cycle in the Great Plains.

One interesting bit of information is the ozone layer tends to reach a maximum at the same time

as the solar maximum, allowing the ozone layer to absorb the excess radiation.

This is thought to affect the tropical Hadley cell circulation and the tracks of mid-latitude

cyclones.

Milankovitch Cycles (Solar irradiance) and Temperature received at 65° N in July (Source: http://www.climatedata.info/Forcing /Forcing/milankovitchcycles_ files/BIGw02-milankovitch-and-temperature.gif.gif

Source: http://a-sceptical-mind.com/an-alternative-solar-theory

SUNSPOT CYCLESVery weak forcing, but significant climate responses to it.

- S

unsp

ots

+

Source: http://oilprice.com/Energy/Energy-General/The-Natural-Chaos-Of-Climate.html

LITTLE ICE AGE (1500-1850 AD)

Cooling was the result of lower solar radiation and some big volcanic eruptions.

NEW DIRECTIONS IN SOLAR VARIABILITY AND CLIMATE CHANGE

• The Total Solar Irradiance has changed by

only 0.3-0.6% since the early 1800s.

• The climate has warmed by 0.5 to 1.0 degrees

C in the same period.

• The correlation between the solar and climate

records can be seen in this figure comparing

polynomial fits to the sunspot record and the

global mean sea-surface temperature. The

Similarity is remarkable.

• It is difficult to imagine that two unrelated

phenomena can have such similar features. Sea S

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1 K

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m M

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Su

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Source: www.swpc.noaa.gov/AboutUs/Review2000/Solar_Irrad_Poster.ppt

CONCLUSIONS

Solar irradiance variability ranges from 0.1% to factors or 10 or more depending on

wavelength. There is strong evidence that the past solar output has changed and this

change has been responsible for changes in the climate. If the sun is cyclic in

nature, it may be possible to forecast future solar irradiance changes.

Forcing is very weak (in visible spectrum), only ±0.1-0.2%, so climate response

should be weak.

Climate response is actually quite high - still not sure why.

One possibility is UV part of spectrum - much greater changes (±10%)

… suggests that global climate is very sensitive

REFERNCES

Eddy, J.A. 1981: Climate and the role of the Sun. In Rotberg and Rabb , 145--67 (5) (1981).

Wang, L., Wheeler, J. C., Li, Z., & Clocchiatti, A. , ApJ, 467, 435. First citation in article | Cross

Ref |ADS (1996)

Radick, R. R., Lockwood, G. W. & Baliunas, S. L. Science 247, 39−44 (1990).

Willson, R. C. & Hudson, H. S. Nature 332, 810−812 (1988).

 Weart, Spencer. Changing Sun, Changing Climate?. The Discovery of Global Warming . Harvard

University Press. ISBN 0-674-01157-0. (2003)

Lean, Judith . Evolution of the Sun’s spectral Irradiance Since the Maunder Minimum.  Geophysical

Research Letters 27 (16): 2425–8.: (2000)

THANKS