Himalayan blunder: Perils of relying on 'grey literature'

Because of the high political and economic stakes involved in climate change, the research limitations that lead to an erroneous conclusion like the vanishing of Himalayan glaciers, won’t be taken lightly. But these are only natural in research process.
As an editorial in the January 21 issue of ‘Nature’ suggests, “Climate science like any active field of research, has some major gaps in understanding. Yet the political stakes have grown so high and the public discourse has become so heated, the climate researchers find it hard to talk openly about these gaps.”
Nobody denies the basics. The greenhouse gas (GHG) emissions are rising constantly and they are the most likely cause behind shooting up of global temperature. The last decade saw many of the warmest years recorded in the last 150 years. Unless the GHG emissions are cut, the world will cross the 2 degrees Celsius ceiling, beyond which lies a region of uncertainty.
But there are doubts if there really is an one-to-one correlation between global warming and anthropogenic activities. Are there natural factors involved? On what basis the IPCC suggests that the last decade was the warmest — is there any fool-proof method of knowing past temperatures?
Knowing previous temperature trends with reasonable accuracy is one of the major challenges dogging the climate change research. Other grey zones are regional climatic forecasts, predicting rainfall pattern and influences of aerosols on which scientists don’t know much till now.
And without better knowledge, it is difficult to draft any adoption and mitigation plans on which hundreds of billions of dollars are claimed by the developing world and $30 billion was committed by the industrialised nations in the short term as per the the controversial Copenhagen Accord.
Why the doubts? Take the paleoclimatic challenges and tree ring controversies for example. To establish authenticity of ‘global warming,’ scientists first need to show rising temperature over the last 800 to 1,000 years. As thermometer measurements are available only for the last 150 years, they rely on indirect sources like tree rings. As trees grows, they develop annual rings whose thickness reflects temperature and rainfall.
In 1998, when climate researcher Michael Mann, University of Virginia, calculated the northern hemisphere temperature over the last 1,200 years, he came out with the famous ‘hockey stick’ curve suggesting a steep temperature rise in the last 50 years. This was attributed to global warming. But this conclusion came under attack from Canadian researcher, Stephen McIntyre, who questioned the methods used for tree ring analysis. Even IPCC now agrees that there are legitimate questions on the tree-ring studies.
Complicated process
Regional climate forecast is another problem area. Scientists use general circulation models (GCM) as the most fundamental tool to forecast how climate will change hundred or two hundred years down the line. The GCMs have parameters representing physical processes on the earth, ocean, atmosphere and ice sheets.
However, the resolution of all GCMs is too coarse to give any meaningful advice to individual countries. If model resolutions are increased to come out with forecast for a specific region or nation, they fail to simulate the future accurately and lead to erroneous results.
Predicting the changes in rainfall is another dicey area. Different simulations used by the IPCC in its fourth assessment report gave out divergent possibilities. The inaccuracy is the most for winter rainfall. Also predicting the behaviour of Indian monsoon that shapes agriculture to a large swath in south Asia will be extremely variable with temperature rise.
There is huge uncertainty on the behaviour of aerosols and their impact on the climate. Atmospheric aerosols include dust particles, black carbon, sulphates and sea salt. All have different survivability and sundry ways to influence the atmosphere. Available data is too inadequate to derive a conclusion.
It’s not that IPCC does not know about the challenges. It admitted having 54 ‘key uncertainties’ that complicate the science of climate change. The glacier controversy, actually raises a broader issue of how much IPCC will allow ‘grey literature’ to come up with conclusions on scientific debate.
Indian geologists claim that available data on Himalayan glaciers too are inadequate. Since conclusions based on arctic glaciers may not be extrapolated to the Himalayas — located at much higher altitude compared to the arctic — more Himalayan data was required.
Instead, IPCC went ahead with non-peer reviewed publications to come up with the poorly substantiated claim of Himalayan glaciers melting away by 2035.
In a communication to the Jan 22 issue of ‘Science’, Canadian scientist J Graham Gogley, Trent University, who took the lid off the glacier misinformation observed IPCC could have avoided the embarrassment had it stuck to “the norms of scientific publication, including peer review and concentration upon peer-reviewed work, been respected.”
The Nobel Prize winning body should better have a relook at the norms on use of grey literature and be more transparent in admitting the scientific challenges in its fifth assessment report.