Greenhouse gas emissions will dry up water resources, warns UN panel

A leaked final draft of the UN scientific panel on climate change report has warned of the risks that the world faces from climate change impacts if the greenhouse gas emissions are not curtailed and countries do not adapt quickly enough.

The report of the Working Group II of the UN Intergovernmental panel on climate change (IPCC) was leaked online. The Hindu confirmed its veracity independently.

The final draft has been sent to all governments to review and comment on before the report is finalised. While the possibility of change in the report during finalisation remains, sources told The Hindu that substantial alteration was unlikely.

The summary for the policymakers – an easy synopsis of the 30 chapter report states, “recent changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Evidence of climate change impacts is strongest and most comprehensive for natural systems, although some impacts in human systems have also been attributed to climate change.”

The summary notes, “In response to on-going climate change, terrestrial and marine species have shifted their ranges, seasonal activities, migration patterns, and abundance, have demonstrated altered species.”

The lack of adaptation efforts in developing countries has lead to significant vulnerability and exposure from extreme climatic events, such as heat waves, droughts, floods and wildfires, the report notes.

The report looks at the impacts already imposed and projects the future impacts based on unchecked emissions of greenhouse gases under different scenarios.

Projecting future impacts, the report warns that there is robust evidence of freshwater availability being hit significantly with increasing emissions. “Climate change will reduce renewable surface water and groundwater resources significantly in most dry subtropical regions, exacerbating competition for water among sectors,” the summary says.

“Each degree of warming is projected to decrease renewable water resources by at least 20% for an additional 7% of the global population,” the summary says specifically.

For agriculture dependent countries such as India, the report warns of ominous changes in crop yields. “With or without adaptation, climate change will reduce median yields by 0-0.2% per decade for the rest of the century, as compared to baseline without climate change.” This would happen against a surging 14% increase in demand of food crops every decade till 2050.

Some of the India and Asia specific impacts and risks are highlighted separately in the graphic along with the story. These are extracted from the Chapter on Asia in the main report. The summary says the key risk to Asia arises from ‘increased flooding leading to widespread damage to infrastructure and settlements, heat-related mortality and increased risk of drought-related water and food shortages causing malnutrition.

The report summary indicates that there are limits to how much change people can adapt to and limits to existing understanding of fighting even current levels of changes in nature. “In some parts of the world, current failures to address emerging impacts are already eroding the basis for sustainable development,” the report says.

The scientific panel also draws from another future report – on mitigation – to warn that emissions are rising so fast and unchecked that “scenarios, which are more likely than not, to limit temperature increase to 2° C are becoming increasingly challenging, and most of these include a temporary overshoot of this concentration goal.”

The first chapter of the report says, “Most of the emission growth between 2000 and 2010 came from fossil-fuel use in the energy and industry sectors, and took place in emerging economies. This emission growth was not met by significant greenhouse gas emission cuts in the industrialized country group, which continued to dominate historical long-term contributions to global carbon dioxide emissions.” With limited space in atmosphere for greenhouse gas emissions, developing countries have long demanded that rich countries need to cut their considerable emissions to create space for others to develop economically before their emissions too peak out. The report notes, “In 2010, median per capita greenhouse gas emissions in high income countries were roughly ten times higher than in low-income countries.”

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Printable version | May 28, 2022 5:14:08 pm | https://www.thehindu.com/sci-tech/energy-and-environment//article60358211.ece