Solar Impact on Climate: Is it Important?

Henrik Svensmark The Danish National Space Institute The Technical University of Denmark Solar Impact on Climate: Is it Important?

The latest report from the IPCC consider only changes in solar irradiance as a possibility, and estimate solar forcing from 1880 to present to be 0.05 W/m2.

In this picture Solar influence on is completely negligible.

2 (Forcing from CO2 is estimated to 1.7 W/m )

Further the latest IPCC 1.5 report suggest that all the temperature increase since 1880 is anthropogenic Super Nova Heliosphere, Cosmic Rays and Solar Activity Cosmic rays in Incoming proton of 100 GeV the atmosphere20 km

Ionizes the atmosphere + - + Produces new cosmogenic isotopes, e.g. 14C, 26Al, 10Be

0 km ICE The link over several millennia The link over several millennia

Little Ice Age

Present CO2 concentrations during the last 10.000 years

It suggest that CO2 cannot have influenced climate during the last 10.000 year. Only during the last part of the 20th century is there is a significant change Δ10BΔe1M 0M(MBHDaoenuoe bnarl(iaenB c&yrgeggΔ ee Jeuer1tot4e t ena Ca a&tlel l..as . 22 lB22.00 00a1010r0981d539 240) 11)

Climate and changes in solar activity AD 800 - 2000

0.5 Moberg et al. 2005

] Huang et al. 2008

C Morice et al. 2011 o Medieval Warm Period Mann & Jones 2003 [ -

s Little Ice Age

e 0.0 i l a n o m

a -0.5 Δ T

-1.0 800 1000 1200 1400 1600 1800 2000

-1.0 -4 ] n . n . n . i i i s n . n . t i i m m t m m

e r -0.5 f o n m o r -2 t O a l ] y u n i S p o r W o l D r % a a u n d e r r [ t 0 M 0.0 C b i r 1 4 a Δ [

2 e 14 Δ C 0.5 B 10 Δ Be (Delaygue & Bard 2011) 1 0 10 4 Δ Be (Beer et al. 1994) Δ 1.0 800 1000 1200 1400 1600 1800 2000 Year Global climate change from borehole temperatures

Measurements from all continents

Borehole Surface

T(z)

S. P. Huang, H. N. Pollack, and P.-Y. Shen, 2008 Quantifying the Solar Link over the 11-year Cycle

Solar Activity Sea Level Change Rate

Using the oceans as a calorimeter Satellite Altimetry

solar + ENSO fit (With linear trend removed!)

Howard, Shaviv & Svensmark JGR (2015) Forcing of climate over the 11-years solar period

2.5 Sea surface temperature Ocean heat content Tide gauges changes Something is 2.0 amplifying Satellite Solar activity. ] 2 are a m /

t candidate t a 1.5 W n g [ i c

o r 1.0 F r a o l S 0.5 Solar Irradiance changes over the 11 year cycle (Measured by satellites) 0.0 Q T h h F Δ Δ SST Δ Tide Δ Sat Δ Clouds Shaviv, 2008 Summary

A significant impact of solar activity on climate is apparent

• Large changes in global climate varying in agreement with solar activity (1-2oC) during the last 10.000 years.

• CO2 cannot explain these variation over most of this period.

• Solar activity is amplified so that the forcing is almost 10 times larger than from solar irradiance alone (over the 11-years period forcing 1.0-1.5 W/m2 is determined from the energy entering the oceans) How can cosmic rays influence climate?

Net effect of clouds is to cool the Earth by about 30 W/m2 Precurser to clouds: Aerosols

Growth ~3 nm ~50 nm

Nucleation Aerosols and microphysics of clouds Satellite observations of ship tracks

Visible: 0.9 mm Link between Low Cloud Cover and Galactic Cosmic Rays? variation

ISCCP IR Low cloud data

10

0

-10

Calibration? -20 Cosmic rays (%)

Svensmark & Friis-Christensen, JASTP 1997, Svensmark, PRL 1998, Marsh & Svensmark, PRL, 2000. (update 2005) Experimental Work 2004 - 2007

q (cm-3 s-1) 0 10 20 30 40 50 60

8 -3 H2SO4 concentration ~ 2*10 (cm )

O3 ~ 25 ppb

SO2 ~ 300 ppt RH ~ 35%

+ + - - ?

1-2 nm stable aerosols Svensmark et al. Proc. R. Soc. A (2007) 463, 385–396 Coronal Mass Ejections Natural experiments for testing the GCR-atmosphere link

We can observe the whole link from solar activity to cosmic rays to aerosols to clouds in the real atmosphere AERONET, SSM/I, MODIS and ISCCP data for 5 strongest Forbush decreases

Aerosols Clouds Liquid water Liquid cloud fraction Low Clouds

Svensmark et al., GRL 2009, Svensmark et al., JGR 2016 IPCC 5AR forcing graph

Solar forcing FIPCC = 0.05 W/m2

Change in solar forcing Evidence that climate sensitivity is small

• Computer model response to volcanoes is too large!

Robock and Mau 1995

Model predictions: Decrease of 0.3-0.5°C. Reality: Decrease of 0.1°C on average Evidence that climate sensitivity is small

Greenhouse models predicts a hot spot where temperatures increase faster than the surface Estimates Climate sensitivity from various reports (Charney and IPCC reports)

How much will the temperature increase if CO2 is doubled?

Climate sensitivity no feedback

Average ~ 3 deg. (Note that the uncertainty has not changed) Empirical estimates of climate sensitivity C) 4 o

3 IPCC range Climate sensitivity no feedback 2

Temperature change ( 1 Basic Climate Model

Ziskin & Shaviv (2012) (elaboration of Lindzen & Giannitsis,1998) 20th century warming Best fit (i.e., after parameter optimization) Comparison: IPCC-AR4

ΔT=0.9±0.3K per CO2 x2 About half of warming caused by solar activity

Residual more than twice smaller than with GCMs (without solar amplification)

Ziskin & Shaviv, 2012 21st century temperature increase 21st century temperature increase Conclusion

❖ Actual evidence points to a strong solar climate link and a low climate sensitivity.

❖ Today we know how the physics behind the link (but in fact, it is totally irrelevant - solar activity should be taken seriously but is ignored!)