HomeWeatherStream flows declining in river basins, affecting agriculture: IPCC author

Stream flows declining in river basins, affecting agriculture: IPCC author

Stream flows have declined in many river basins while extreme rainfall events, as well as dry spells, are likely to increase in India during the next few years. This can make water management for agriculture challenging. The latest report of the Intergovernmental Panel on Climate Change (IPCC) released on Monday indicates the effectiveness of most adaptation measures, including water-related measures, falls sharply at higher levels of global warming above 1.5-degree C, showing that adaptation alone will not solve the crisis. Aditi Mukherji, a researcher at International Water Management Institute and contributing lead author for the chapter on the water in the IPCC report, spoke to HT about immediate mitigation measures needed to prevent severe impacts on water resources. Edited excerpts:

How has the 1.1-degree C warming impacted the rivers and water resources in India and South Asia?

There are observed declines in stream flow change in many river basins in South Asia. However, quantification of the contribution of anthropogenic climate change to current levels of water scarcity is not yet available. The melting of glaciers is clearly an artefact of rising global temperature levels. Himalayan glaciers like glaciers elsewhere in the world have seen unprecedented melting in the last few decades, with widespread impacts for people directly dependent on glacier meltwater resources – indigenous groups and small holder farmers in the Himalayas.

How is the 1.5-degree warming likely to impact hydrological systems globally? Which are the systems most vulnerable to change?

All components of the hydrological cycle are projected to intensify at 1.5 degrees and above as…our report also reiterates. Extreme precipitation events are likely to increase as are dry spells within two rain events, making agricultural water management even more challenging.

How is glacier melt in the Himalayas likely to affect rivers and water availability downstream?

Yes, to a certain extent, especially in the immediate downstream where populations like mountain farmers and Indigenous groups depend on glacier meltwater for agriculture and also cultural uses of water. However, monsoons are also projected to intensify and the Ganga and Brahmaputra, unlike Indus, get a large share of their run-off from the monsoon rains than from glacier melt, and hence total water availability is not expected to reduce drastically. However, flow seasonality and hazards caused by extreme precipitation are likely to increase, and we have already observed increasing trends in droughts (their likelihood and intensity) in India. Water-related hazards (floods, droughts, extreme rainfall events, melting of glaciers) remain the dominant way in which a large share of our region’s population is experiencing climate change… in other words, climate change impacts get manifested first and foremost through water impacts.

What do these hydrological impacts mean for people in India and South Asia?

Intensification of the global hydrological cycle means more extreme precipitation events, but also longer drier spells. However, we also need to remember that while climate change will exacerbate water management challenges in the region, the core of management challenge is still related to misaligned policies and poor governance. We need to focus on aligning water policies with other policies, particularly food policies to ensure proper management of water.

Extreme precipitation events, especially in more dry land setting (like peninsular India), is giving rise to what is called “episodic” recharge, where a large amount of recharge is happening during these extreme rainfall events. However, overall, in the case of the groundwater in the region, the main cause of over exploitation remains socio-economic and policy oriented and comes from misaligned policies. Our policies encourage growing water intensive crops in areas with low rainfall and low recharge, while areas with high rainfall and recharge often have restrictive groundwater policies. Climate change is only making these existing problems worse.

How are people adapting to climate change?

Our report finds that a majority (~60%) of all adaptation is happening in response to water-related hazards, particularly in sectors like agriculture, which is hugely exposed to impacts of climate change. In the context of India, we already know that irrigation, soil moisture conservation, water storage, rainwater harvesting is some of the oft-used adaptation solutions by farmers and they are beneficial in buffering them from both long-term climate impacts and short-term rainfall variability. Water, therefore, is an important part of the solution.

Will adaptation help us overcome the climate crisis?

Adaptation is a very important part of managing climate change impacts. However, our chapter and the report found that the effectiveness of most adaptation measures, including water-related measures, falls sharply at higher levels of global warming above 1.5 degrees, showing that adaptation alone will not solve the crisis. We need mitigation as, without mitigation, space and scope for adaptation will fall drastically.

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