'Solar changes need to be given more insight'

Bangalore, Jan 6: Solar changes may lead to an average of just about 0.5 degrees change in the earth's temperature, but the contribution of the greenhouse gases such as anthropogenic carbon dioxide to global warming is real and needs urgent attention, noted physicist Prof E N Parker has said.

Speaking at the inaugural Vainu Bappu Memorial Lecture on 'The Sun, Space, Cosmic Rays and Climate' at the Indian Institute of Astrophysics here, he said ''The current status of our understanding of the sun and the cosmic rays, and their impact on the earth's climate is far from complete. The hydrodynamics of the sun still needs to be understood better.'' Talking about solar wind, which affected astronauts and satellites in space, he pointed out that it was not thrown as bullets, but started slowly from the sun and got accelerated as it moved away from it.

Prof Parker, the former S Chandrasekhar Distinguished Service Professor at Enrico Fermi Institute, Chicago, had made seminal contribution to the understanding of solar wind for the past 50 years. He revolutionised solar physics in the 1960s with his deduction that there must be a constant, supersonic flow of plasmas from the sun.

He pointed out that variations in output from the sun to the extent of one part in thousand was sufficient to cause climatic changes, leading to little ice ages or global warming on the earth.

The magnetic fields from solar interior show up as sunspots on the surface and display an 11 year cycle of activity. Such cycles of activity were correlated to a modulation of the emission from the sun and these in turn have signatures of climatic changes on earth.

Prof Parker threw light on some of the recent findings that the cosmic rays appear to assist in cloud formation in earth's atmosphere. The cosmic rays produce ions which seed the formation of clouds. Studies were now on to find the cosmic ray-ions-cloud formation relationship.

Allaying fears of possible asteroid or meteor collision with the earth at the inaugural function on Thursday, he said chancs of such a happening was extremely small.

UNI