What physics can say about climate changes American Physical Society Racah Institute of Physics Workshop  What physics can say about climate changes December 25, Danciger B Seminar room, Afternoon (25.12.13 @ 16.00)

Program 16.00 – 16.10 Prof. Miron Ya. Amusia Introduction 16.10 – 17.10 Prof. Nir Shaviv The Role of the Solar Forcing in the 20th century climate change, 17.10 – 17.40 Prof. Daniel Rosenfeld The dominant role of aerosol cloud-mediated forcing in the uncertainty of anthropogenic climate forcing and climate sensitivity. 17.40 -18.00 - General discussion

SOME COMMENTS  Previously it was scheduled for 12.12.13: a snow storm and cold strongest in last 60-100 years prevented this event. At the same time in Moscow and Saint Petesrburg there was no snow and it was warm. Can it all be human made “global warming”? I doubt. Simplest explanation are ordinary fluctuations. Perhaps we see some results of movement of the magnetic axis of the Earth relative to the axis of rotation (Prof. D. A. Varshalowich).

Choice of Date - MISSED OPPORTUNITY Not used symmetry It could be 11.12.13 @14.15 … Such an opportunity will appear in next millennium Day 11.12 Year 3013 Time 14.15 Perhaps: NO WORKSOPS ? NO CLIMATE?? NO TIME???

The Role of the Solar Forcing in the 20th century climate change Prof. Nir Shaviv Was born in Ithaca NY, 1972. 2012- Full Professor at the Hebrew University 2000 The Beatrice Tremaine Award (given by CITA) 2004 The Siegfried Samuel Wolf Lectureship in nuclear physics (HU) Frequent guest at CNN, BBC and even Vremya (in Russia)

Abstract: Empirical results show that solar variations play an important role in climate change. We try to understand why such variations are crucial in 20th century climate change, and how it is related to the climate sensitivity. The latter is necessary to predict future climate change. We review some of the evidence, particularly, the data which can be used to quantify the size of solar climate link. We discuss the mechanism responsible for the large link - cosmic ray ionization and its effect on climate. We end with a more consistent picture for 20th century global warming, mentioning some words on 21st century climate change.

The dominant role of aerosol cloud-mediated forcing in  the uncertainty of anthropogenic climate forcing and climate sensitivity Prof. Daniel Rosenfeld M.Sc. The Hebrew University, Radar Meteorology, 1980 Ph.D. The Hebrew University, Cloud physics, 1980 February 2006: The WMO/UAE Prize for Excellence in Weather Modification 2006: The Michael Landau Prize for Sciences, in the area of Ecology and Environment 2007: The Schaefer Award, of the Weather Modification Association BBC, CNN, Multiple press releases

Abstract: Anthropogenic emissions of aerosols and their precursors counteract positive (warming) radiative forcing due to the emitted greenhouse gases, by reflecting more solar energy back to space directly and through their impacts on cloud properties. While positive radiative forcing due to Green House Gases (GHG) is relatively well known, the cloud-mediated aerosol radiative forcing is a result of very complex processes which are difficult to document and quantify. Therefore uncertainty in cloud-mediated aerosol radiative forcing dominates the overall uncertainty of anthropogenic climate forcing. Climate sensitivity is the extent of global warming for a given amount radiative forcing. Aerosols negative (cooling) radiative forcing hides part of the warming due to GHG to an unknown extent and thus renders the climate sensitivity quite uncertain. Here main mechanisms responsible for uncertainty in aerosol radiative forcing and implications to the global picture will be reviewed.

Views on “human” global warming M. I. Budyko (1920-2001), climatologist, Developed a mathematical model of climate change, based on energy balance. Author of «Human effect on climate» (1972), that predicts From 1975 headed USSR-US Climate group. (Intergovernmental). Flows in the models. Consequence – trillions lost

Views on “nuclear winter” K. Sagan (1934-1996), US astrophysicist and writer, suggested the “nuclear winter” N. N. Moiseev (1917-2000), in 1983 developed a mathematical model of the “nuclear winter. Moiseev and late V. V. Alexandrov gave a talk about their model at the theory department of Ioffe Physical-Technical Institute. Flows in the model – forgot about oceans.

View on “ozone holes” Main “ozone hole” with D > 1000 km discovered over Antarctic in 1985. Attributed to emission of freon that is used as cooling agent in refrigerators. An whole industry was destroyed. Natural causes proved to be more powerful. Role of El Gore in “promotion” of human role in hole creation.

Naïve view on all human effects Humans contribute less than 0.1 mg/cm2. Energy flows connected to humans are incomparable less than natural – e.g. volcano eruptions. Thus, strong effects can be either local or due to instability of the noosphere. If unstable, it would permanently alter due to natural causes. Scientists – be careful, do not overestimate your knowledge and understanding.

The podium is yours, our reliable and careful experts At first Nir and then Daniel