Guest essay by Eric Worrall

A new study has emerged predicting the end of snow, along with melting glaciers and water shortages – though this study is cautious enough to predict more snow, less snow, or no change, for at least the next few decades.

The potential for snow to supply human water demand in the present and future Justin S Mankin, Daniel Viviroli, Deepti Singh, Arjen Y Hoekstra and Noah S Diffenbaugh Abstract Runoff from snowmelt is regarded as a vital water source for people and ecosystems throughout the Northern Hemisphere (NH). Numerous studies point to the threat global warming poses to the timing and magnitude of snow accumulation and melt. But analyses focused on snow supply do not show where changes to snowmelt runoff are likely to present the most pressing adaptation challenges, given sub-annual patterns of human water consumption and water availability from rainfall. We identify the NH basins where present spring and summer snowmelt has the greatest potential to supply the human water demand that would otherwise be unmet by instantaneous rainfall runoff. Using a multi-model ensemble of climate change projections, we find that these basins—which together have a present population of ~2 billion people—are exposed to a 67% risk of decreased snow supply this coming century. Further, in the multi-model mean, 68 basins (with a present population of >300 million people) transition from having sufficient rainfall runoff to meet all present human water demand to having insufficient rainfall runoff. However, internal climate variability creates irreducible uncertainty in the projected future trends in snow resource potential, with about 90% of snow-sensitive basins showing potential for either increases or decreases over the near-term decades. Our results emphasize the importance of snow for fulfilling human water demand in many NH basins, and highlight the need to account for the full range of internal climate variability in developing robust climate risk management decisions.

Read more: http://iopscience.iop.org/article/10.1088/1748-9326/10/11/114016

What a pointless effort. The authors predict water shortages which might occur in the near future, but also claim climate variability may mask this effect for decades to come. The authors present a claim of imminent potential danger, with no possibility of imminent falsification. All the predictions are based on climate models, which have never demonstrated predictive skill with average global climate, let alone regional climate.

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