This document discusses the relationship between solar variation and climatic changes. It introduces that the sun provides the energy that drives Earth's climate and any changes in the sun's output can affect the climate. It then covers topics like how solar variation is measured, records of past solar activity, the relationship between solar activity and historical climate changes like the Little Ice Age, and conclusions that the climate appears to be highly sensitive even to small changes in solar irradiance.

1. SOLAR VARIATION AND CLIMATIC
CHANGES
By- Dr. Vinay Kumar Pandey
Dr. Ajai Mishra,
Dr. Shashank Shekhar Mishra

2. 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.

3. SUNSPOTS

4. 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

5. 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)

6. 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) .

7. 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.

9. 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

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

11. SUNSPOT CYCLES
Very weak forcing, but significant climate responses to it.
- Sunspots +
Source: http://oilprice.com/Energy/Energy-General/The-Natural-Chaos-Of-Climate.html

12. LITTLE ICE AGE (1500-1850 AD)
Cooling was the result of lower solar radiation and some big
volcanic eruptions.

13. 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.
Sunspot Number
Sea Surface Temperature .01 K Departure
from Mean
Source: www.swpc.noaa.gov/AboutUs/Review2000/Solar_Irrad_Poster.ppt

14. 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

15. 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)