Above suspicion?

THE conclusions of 11th plenary meeting of the Intergovernmental Panel on Climate Change (ipcc) held at Rome, Italy, in December 1995, continue to be debated. The most contentious declaration made by the ipcc states that the "Human influence (in bringing about global climatic changes) is clearly discernible". It is alleged that the ipcc's summary report which presents the proceedings of the meet in a mitshell, has selectively highlighted certain issues while choosing to ignore others. Concerns over the misleading nature of information provided by the summary report are great because it is the most widely-read document brought out by the ipcc's Second Assessment Report documents (Ecoal, April 1996).

A variety of reasons have generated this criticism of ipcc's summary report. Most of the ipcc's climate change forecasts are based on computer models (general circulation models), and have ignored the temperature measurements of the lower troposphere (the lowest region of the atmosphere extending from between eight and 18 kin), which have been made by satellites and radiosondes (weather balloons).

The latter had been presented by the ipcc's working group. They indicate a slight overall decline in temperature since 1979, the year when constant satellite monitoring was initiated. On the other hand, measurements of global surface temperature; indicate a slight warming over the same period.

Fred Singer, president of the Science and Environmental Policy Project, believes that the ipcc's report is deceptive. According to him, the report correctly states that the climate has warmed by 0.3'c to 0.6'c, in the past century. However, it does not mention that there has been little if no warming in the last 50 years - a time when about 80 per cent of the greenhouse gases were added to the atmosphere. In this context he mentions that the findings Of NASA'S (National Aeronautics and Space Administration, us) satellites - regarded as true global measurements - show no warming at all; in fact, they report a cooling trend. The NASA data has been overlooked by the ipcc. Singer also ciriticises the ipcc for failing to mention the discrepancy in results. "With climate models lacking validation, why should we trust any of the forecasts about say future warming or rise in sea levels? And why should we be using them as a basis to formulate costly policies ?" he questions.

Some scientists do admit that satellite data does not always give an accurate picture of surface temperature, but when'its trends are compared with radiosonde data, the two match rather well. Radiosonde measurements over the polar region, in the past 40 years, indicate no evidence of warming. Singer draws attention to the fact that though there is a common consensus among scientists about the rise in surface temperatures, the ipcc is itself sceptical about the legitimacy of surface temperature records. These doubts are listed in their 1992 report with the reasons for inefficiency (incomplete spatial coverage, changes in schedules, practices and station location and occurrence of urbanisation around many stations, among others).

Accu-Weather, a leading commercial weather forecasting firm states that hemispheric satellite data, rather than surface temperature data, must be taken as a representative of global atmospheric temperature. The former is more uniformly distributed and covers a larger surface. They feel that if there were any significant changes taking place on the surface, they would be manifested in the lower troposphere too and satellites would be recording the same. And till now, no such trends have been observed in satellite data. Hence, according to Accu-Weather, not much could be happening at the surface level. The ipcc also fails to mention some of the positive aspects of global warming. For instance, the number of droughts faced by the American heartland may be rising but conditions are getting more moist.

The summary for policymakers also says, "Our ability to quantify human effect on climate is currently limited by uncertainties in key factors including long-term natural variability and time evolving patterns of radiative forcing by greenhouse gases and aerosols". This point is totally overlooked in the next paragraph which concludes by saying that "Taken together, these results point towards a detectable human influence on global climate."

What surprises most scientists is that despite the existing uncertainties, the ipcc has taken a formal stand to 'confirm' the human hand in global warming. Robert Balling, director of climatology at the Arizona State University at Tempe, us, said that policymakers do not have the time to go through the entire document and will instead read the summary report or rely on the media. Therefore, he stresses the point that the information supplied to the media should be correct and complete. News accounts misinterpret reality when they use selective information. They either make exaggerated claims or miss out the small but important details. Ultimately, what goes beyond doubt is that we are still in the dark about the uncertainties in climate.