Physicist U.R. Rao says carbon emission impact is lower than IPCC claim

A key belief of climate science theology — that a reduction in carbon emissions will take care of the bulk of global warming — has been questioned in a scientific paper released by the Environment Ministry on Monday.

Physicist and the former ISRO chairman, U.R. Rao, has calculated that cosmic rays — which, unlike carbon emissions, cannot be controlled by human activity — have a much larger impact on climate change than The Intergovernmental Panel on Climate Change (IPCC) claims.

In fact, the contribution of decreasing cosmic ray activity to climate change is almost 40 per cent, argues Dr. Rao in a paper which has been accepted for publication in Current Science, the preeminent Indian science journal. The IPCC model, on the other hand, says that the contribution of carbon emissions is over 90 per cent.

‘Cosmic ray impact ignored'

Releasing Dr. Rao's findings as a discussion paper on Thursday, Environment Minister Jairam Ramesh noted that “the impact of cosmic ray intensity on climate change has thus far been largely ignored by the mainstream scientific consensus.” He added that the “unidimensional focus” on carbon emissions by most Western countries put additional pressure on countries like India in international climate negotiations.

The continuing increase in solar activity has caused a 9 per cent decrease in cosmic ray intensity over the last 150 years, which results in less cloud cover, which in turn results in less albedo radiation being reflected back to the space, causing an increase in the Earth's surface temperature.

While the impact of cosmic rays on climate change has been studied before, Dr. Rao's paper quantifies their contribution to global warming and concludes that “the future prediction of global warming presented by IPCC's fourth report requires a relook to take into the effect due to long term changes in the galactic cosmic ray intensity.”

Policy implications

This could have serious policy implications. If human activity cannot influence such a significant cause of climate change as cosmic rays, it could change the kind of pressure put on countries to reduce carbon dioxide emissions.

Mr. Ramesh emphasised that Dr. Rao's findings would not reduce domestic action on climate change issues, but he admitted that it could influence the atmosphere of international negotiations.

“International climate negotiations are about climate politics. But increasingly, science is becoming the handmaiden of politics,” he said.

In November 2009, Mr. Ramesh had released a report by glaciologist V.K. Raina claiming that Himalayan glaciers are not all retreating at an alarming pace. It had been disputed by many Western scientists, while IPCC chairman R.K. Pachauri dismissed it as “voodoo science.” However, Dr. Raina was later vindicated by the IPCC's own retraction of its claim that the Himalayan glaciers would melt by 2035.

“Since then, Western Ministers have reduced talk about the glaciers to me, they have stopped using it as frequently as a pressure point for India to come on board,” said Mr. Ramesh.

When Mr. Ramesh sent Dr. Rao's paper to Dr. Pachauri, he replied that the next IPCC report was paying special attention to the impact of cloud cover on global warming. The Minister expressed hope that Dr. Rao's findings would be seriously studied by climate researchers.

“There is a groupthink in climate science today. Anyone who raises alternative climate theories is immediately branded as a climate atheist in an atmosphere of climate evangelists,” he said. “Climate science is incredibly more complex than [developed countries] negotiators make it out to be… Climate science should not be driven by the West. We should not always be dependent on outside reports.”

Disputing IPCC claims

According to the latest report by the IPCC, all human activity, including carbon dioxide emissions, contribute 1.6 watts/sq.m to global warming, while other factors such as solar irradiance contribute just 0.12 watts/sq.m.

However, Dr. Rao's paper calculates that the effect of cosmic rays contributes 1.1 watts/sq.m, taking the total contribution of non-human activity factors to 1.22 watts/sq.m.

This means that increased carbon dioxide emissions in the atmosphere are not as significant as the IPCC claims. Of the total observed global warming of 0.75 degrees Celsius, only 0.42 degrees would be caused by increased carbon dioxide. The rest would be caused by the long term decrease in primary cosmic ray intensity and its effect on low level cloud cover.

This means that predicting future global warming and sea level rise is not as simple as the IPCC makes it to be, since it depends not only on human activity, but also significantly on the unpredictability of cosmic ray intensity.

“We conclude that the contribution to climate change due to the change in galactic cosmic ray intensity is quite significant and needs to be factored into the prediction of global warming and its effect on sea level raise and weather prediction,” says the paper.


  • ‘Unidimensional focus on carbon emissions put additional pressure on countries like India'
  • Increased solar activity caused 9 p.c. decrease in cosmic ray intensity, resulting in less cloud cover