My Bookmarks on Science & Technology, Climate Change, Astrobiology, Genetics, Evolution

January 31, 2010 – Original Source: The Times of India

After more than 20 years of concerted international effort, our understanding of the impact of human activity on the climate has improved dramatically. The results are sobering: unchecked, greenhouse gas emissions are leading to higher temperatures and sea levels, greater stresses on water supplies, and changes in ecosystems. They are also a leading factor in the retreat of most of the world’s glaciers.

But to judge from the hue and cry emanating from the IPCC’s recent withdrawal of its published estimate that Himalayan glaciers could disappear by 2035, one would think that an entire body of knowledge, produced by thousands of scientists, was now in disarray. What exactly happened?

The IPCC mistakenly published a figure that was not drawn from peer-reviewed literature, disregarding its stringent review processes. The scientific body has made a formal apology and has promised a stricter review process for the upcoming Fifth Assessment Report, which will summarize the current state of climate change science. Climate science plays a complex and important role in shaping vital policy decisions. Any misstep in the IPCC process is therefore of concern, and must be remedied. But it does not challenge the basis of climate change science, or evidence of global warming that is already visible across the globe.

Still vital, and still at risk

The world’s glaciers are natural reservoirs, storing valuable freshwater on remote mountains for much of the population on our planet. For communities downstream of mountain glaciers and snowfields, most of the energy, agriculture and municipal infrastructures have been developed in the context of an annual cycle of winter snowfall and gradual melt-water runoff during the dry season. The disappearance of those glaciers would have enormous socioeconomic impact around the world. And that process is already underway. To take one example, as the Andean glaciers retreat, the loss of hydroelectric power is estimated to cost Peru $1.5 billion annually. Also, flow of river water to its densely populated coasts is dropping alarmingly.

The largest concentration of non-polar glaciers sits atop the Tibetan Plateau, releasing water into the Indus, Satluj, Brahmaputra, Mekong, Yangtze and other river systems, providing freshwater to more than a billion people. On the Tibetan Plateau, areas above 4,000 metres have already warmed by 0.9 degrees Celsius over the last three decades, twice the global average. This change brings with it shorter winters and less snow cover at higher elevations. The glaciers will not be gone by 2035, but the water they store will diminish throughout the region. This means additional stress on the region’s already limited freshwater supply. In recent years, groundwater level in northern India has been dropping one metre every three years. Meanwhile, demand for water in India is projected to double in the next 20 years. These additional stresses combined with regional warming pose a major challenge to the availability of adequate water supplies for the region in future.

The need for action

More scientific research, subject to careful peer review, remains as important as ever. We do not know nearly enough about glacier behaviour, or about how the different drivers of water supply interact. Even if we were armed with better data, climate change is riddled with variability and surprises. But the fundamental trends are clear. Glaciers are in retreat around the globe. In part, this is due to black soot from burning coal and diesel, and the inefficient use of biomass, which darkens the glaciers and makes them soak up more sunlight. In part, it is due to the global rise in temperatures driven largely by the greenhouse gases pumped into the air by human activity, particularly burning fossil fuels.

This assessment is not based on a handful of studies, but on multiple independent lines of evidence that are supported by the collective work of thousands of scientists from institutions worldwide. It relies not on the esoteric, but on the basic laws of physics. And it is a conclusion reached not only by the IPCC but by leading scientific bodies in over a dozen major countries, including India, China and the US.

These risks warrant concerted efforts in cutting back on greenhouse gas emissions as well as preparing for a changing world via adaptation interventions. If there is any good news here, it is that there is still time to act but that window is closing quickly. Cleaner energy sources that eliminate both soot and greenhouse gases can slow the warming while building new industries. Restored forests can slow warming further while helping manage the water systems in a better way. And smarter agricultural planning can prepare us for a world with less glacial freshwater. This will take some political courage, but the end result will be a safer and more prosperous world.


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