The connection between cosmic rays, and climate

Henrik Svensmark, Jacob Svensmark*, DTU Space *Dark Cosmology Centre, University of The connection between cosmic rays, clouds and climate

1. The cosmoclimatological hypothesis – Origin of cosmic rays – Linking cosmic rays to climate – Presentation of the hypothesis 2. The final piece of the puzzle – The microphysical mechanism, theoretically and experimentally – How relevant is cosmic rays for climate in the real atmosphere? 3. Conclusion Cosmic Rays

Super Nova Remnant Acceleration of cosmic rays

Solar magnetic field

Solar system Cosmic rays in Incoming proton the atmosphere 20 km of 100 GeV

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

0 km ICE Strong coherence between solar variability and the monsoon in Oman between 9 and 6 kyr ago

The formation of stalagmites in northern Oman has recorded past northward shifts of the intertropical convergence zone3, whose northward migration stops near the southern shoreline of Arabia in the present climate

U. Neff et al., Nature 411, 290 - 293 (2001) How can STARS influence Climate?

Net effect of clouds is to cool the Earth by about 30 W/m2 Link between Low Cover and Galactic Cosmic Rays? variation ISCCP IR Low cloud data

10

0

-10

Calibration? -20

Svensmark & Friis-Christensen, JASTP 1997, Svensmark, PRL 1998, Marsh & Svensmark, PRL, 2000. (update 2005) Empirical evidence for a relation between cosmic rays and climate

If the link is between cosmic rays and clouds, what would the mechanism be? Precurser to clouds: Aerosols

Cosmic Ray Ionization

Growth CLOUD

1-2 nm stable aerosols Cloud Condensation Nuclei > 50 nm Aerosols and microphysics of clouds Satellite observations of ship tracks Visible: 0.9 mm Experimental challenges 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%

+ + - - ? Svensmark et al. Proc. R. Soc. A (2007) 463, 385–396 1-2 nm stable aerosols So experimentally there is good evidence for the generation of ultrafine aerosols by ions ~ 1-3 nm

• An important remaining question: Will the small aerosols grow to Cloud Condensation Nuclei (~ 50 nm) ? Nucleation If not no impact on clouds.

CCN RESULTS FROM GEO-CHEM-TOMAS Global Circulation Model (No ion-effects on growth) Solar cycle response 10.00

Expected range to explain observations 1.00

CCN Aerosols 0.10 Relative change [%] NUCLEATION

0.01 1 10 100 Diameter [nm]

Data from: Snow-Kropla et al. 2011 Modeling says NO to an effect of ions on CCN Is the theory dead again?

TESTING THE GROWTH OF AEROSOLS EXPERIMENTALY Addition of ”neutral” aerosols

CCN

More particles compeating for the same gas, therefore slower growth and larger losses, as also seen in model results.

Svensmark, Enghoff, Pepke Pedersen Physics Letters A 377 (2013) 2343–2347 Addition of aerosols using ionization

CCN

Contradicts the model results

Svensmark, Enghoff, Pepke Pedersen Physics Letters A 377 (2013) 2343–2347 Coronal Mass Ejections Natural experiments for testing the GCR-atmosphere link Cosmic rays [counts] Cosmic rays AERONET, SSM/I, MODIS and ISCCP data for 5 strongest Forbush decreases

Aerosols Clouds Liquid water Liquid cloud fraction Low Clouds

Svensmark, Bondo, Svensmark, Geo. Phys. Lett., 2009 Svensmark, Enghoff, Shaviv, Svensmark, J. Geophys Res., 2016 Experiments and observations suggest that aerosols grow to Cloud Condensation Nuclei

Will cosmic rays help the growth What mechanism ? is responsible ?

CLOUD

1-2 nm stable CCN > 50 nm aerosols GROWTH ?

Mainly from H2SO4–H2O gas The Breakthrough 2015-2017 Cosmic Rays

Ions Aerosols

- + Aerosol Ions + -

+ +

- Maerosol+mion -

mion Maerosol Maerosol+mion

A so far ignored effect A few numbers Growth from neutral molecules

6 3 H2SO4-H2O ~ n0 ~ 10 molecules/cm

Growth from ions

Ions ~ 103 ions/cm3 Naively: -3 + Aerosol GRion/GR0 ~ nion/ n0 ~ 10 ~ 0.1%

1. Coulomb forces 2. Mirror forces 3. Van der Waals forces 4. Viscous forces

nion 10% atm. GRion/GR0 = G(n0, nion, m0, mion ,d) ~ 70 ~ n0 1% exp. After 3100 Hours of measurements we get:

6 ∆q = 45 ion-pairs cm-3s-1 -3 -1 5 ∆q = 186 ion-pairs cm s

- 1.6 4 v6 v5

3 [%] v9 - 1.3 v8 ion T [min] - 1.2 ∆ 2 v10 v4 - 1.0

v11 (dr/dt) v3 v1 - 0.9 ∆

Growth rate [%] rate Growth - 1 v7 0.8 v2 - 0.5 D 0 - 0.0

2×107 3×107 4×107 5×107 6×107 3 H2SO4 [molecules/cm ] Theory and experiments are consistent ! Svensmark, Enghoff, Shaviv & Svensmark, Nature Communications 2017 DOI: 10.1038/s41467-017-02082-2 60 a) 2.0 20

10 1.0

Diameter [nm] Diameter 5

3 0.0 0 100 200 300 Time [Hours] 20

b) e 1 2.0 Profil Profile 2 15

10 le 2 1.0 Profile 1 Profi Diameter [nm] Diameter

5

0.0 0 1 2 3 4 Time [Hours] Summery of influence of cosmic rays on clouds ionization

Nucleation Growth Droplet formation Cloud

Important: The cosmic ray effect on growth is independent on how small particles are made. Atmospheric Relevance HADLEY CIRCULATION . 6 -3 nH2So4~1-3 10 cm Supernova Remnant Time of growth 5-7 days

Sun GCR Solar Wind GCR Solar Wind

ITCZ Convergent zone

40 South Equator 40 North OCEAN Summary

1. Cosmic rays assist the nucleation of small aerosols (1-1.5 nm) 2. Growth of aerosols to CCN assisted by cosmic ray ionization (Microphysical mechanism identified) 3. Explain results on Forbush decreases which result in variations in aerosols and clouds 4. Consistent with climate changes over the Holocene (last 10.000 years) 1-2 oC 5. Consistent with over geological time scales 5- 10 oC, e.g. last 500 million years. Note that these variations are independent of solar varibility. Climate and our galactic environment Carbon 13 and super nova activity

8 1.5 6

4 1.0

2 C [per mill] SN(t)/SN(0) 13 0.5 0 δ

-2 0.0 -500 -400 -300 -200 -100 0 Time [Myr] Svensmark, Mon. Not. R. Astron. Soc., 423, 1234-1253 (2012) Conclusion

• The ions produced of cosmic rays, help the formation clusters to form and become stable against evaporation. This process is called nucleation and results in small clusters (aerosols).

• The second role of ions is that they accelerate the growth of small aerosols into cloud condensation nuclei – seeds on which liquid water droplets form to make clouds. The more ions the more aerosols become cloud condensation nuclei.

IMPLICATIONS • When the Sun is lazy, magnetically speaking, there are more cosmic rays and more low clouds, and the world is cooler. When the Sun is active fewer cosmic rays reach the Earth and, with fewer low clouds, the world warms up.

• Cooling’s and warmings of around 2 oC have occurred repeatedly over the past 10,000 years, as the Sun’s activity and the cosmic ray influx have varied.

• Over many millions of years, much larger variations of up to 10oC occur as the Sun and Earth, travelling through the Galaxy, visit regions with more or fewer exploding stars. Cosmic rays from Meteorites Titanium 44 (Half-time 63 years)

Stone meteorite

Taricco et al. 2006

Eleanna Asvestari Ilya G. Usoskin Gennady A. Kovaltsov Mathew J. OwensNatalie A. Krivova Sara Rubinetti Carla Taricco Monthly Notices of the Royal Astronomical Society, Volume 467, Issue 2, 2017, 1608–1613, Quantifying the Solar impact:

Sun

Sea Level Change Rate

Shaviv 2008 Ocean Heat Content

Sea Surface Temperature

Sea Level Change

Altimetry Data Require Quantifying Total Solar Irradiance Solar Total mechanism an an over 11 over11 amplification Solar Solar years Shaviv Forcing CLOUDS , 2008 Climate and our galactic environment pt. 2 Cosmic rays and climate over the last 10.000 years

Bond et al, Science 294, 2001

According to icecores

CO2 levels has been constant ~280 ppm

Last 1000 years Little Ice Age • Little Ice Age is merely the most recent of a dozen such events during

the last 10.000 years 36 Adapted from Kirkby tot 25

Ν a) / 20 0 G in theory Ν

15 0,0

β 10 / change in % of effective growth velocity

+-,0 5 β

4 0 Important1 for the survivability10 of aerosols100 1000 0 b) 50.0 20. 30.0 0 10. 10000 30.0

s] 100 3 ] 5.0 3 20.0 [ions/cm

0 0 ion 10 10. 2. n q [ion-pairs/cm

5.0 1.0 1000 1

1 10 100 d [nm]

6 3 [H2SO4] ~ 10 molecules/cm Even the details in the theory fits the experiment

10 6 10 a) b) c) 8 8 4 6 6

2 4 4

T [min] 2 T [min] 0 T [min] 2 Δ Δ Δ

0 0 -2 -2 -2

-4 -4 -4

6 8 10 12 14 16 18 20 6 8 10 12 14 16 18 20 6 8 10 12 14 16 18 20 d [nm] d [nm] d [nm] mean= 1.23743