The Intergovernmental Panel on Climate Change (IPCC) published a new International Climate Assessment on 9th August 2021. It warned that the water cycle has been intensifying and will continue to intensify as the planet warms.
It means that as the climate breakdown takes hold, water problems like droughts, its accompanying wildfires, floods are likely to become much worse, and global heating of at least 1.5°C is likely to happen within the next two decades, according to the IPCC.
The temperature rise will be accompanied by big changes in the planet’s water cycle and will lead to areas that are already wet becoming much wetter. The already arid areas will become prone to greater drought as extreme rainfall intensifies by seven percent for each additional 1°C of global heating, the report found.
Prof Mike Meredith, science leader at the British Antarctic Survey, said: “As the atmosphere continues to heat up because of global heating, it can hold and transport more moisture – so at the largest scale we expect to see an acceleration of the hydrological cycle: stronger evaporation in the tropics, and more intense rainfall in the high latitudes and some equatorial regions. This will lead to more frequent extreme rainfall events in already wet areas, and a greater incidence and severity of flooding.”
“There is already strong evidence that we are seeing such changes. In some dry regions, droughts will become worse and longer-lasting. Such risks are compounded by knock-on consequences, such as greater risk of wildfires, such as we are already seeing,” said Meredith, who is also the lead author for the IPCC.
Intensifying water cycle
Prof Ralf Toumi said that the principle of a warmer world is that more water will be evaporated, which will exacerbate droughts. The co-director of the Grantham Institute on Climate Change at Imperial College London, added: “This enhanced water in the atmosphere will increase the amount of rain when it does rain.”
The effects of the same will be felt across the globe such as from:
- The United States (where droughts are an increasing problem in the west and south).
- India (where the monsoon may become more variable.)
- Sub-Saharan Africa (likely to experience increased drought in many areas).
- Flooding and drought will hit China and Europe.
“Climate change will make wet and dry regimes more extreme. Soil moisture will go down and dry spells will go up in already arid regions such as the Mediterranean and southern Africa,” said Ilan Kelman, professor of disasters and health at University College London. “Seasonal rainfall variability is expected to increase, with fewer days of rainfall alongside increased intensity of downpours.”
Heavy monsoon rains are disrupting life across the Indian subcontinent.
The impacts on monsoons
One of the biggest impacts of the climate crisis is the changes to the planet’s natural rainfall patterns. The monsoon in south Asia becomes a particular source of concern as it is crucial to the lives and agriculture of over a billion people. Another concern is the glacier-fed areas, where two problems – first flooding and then water scarcity are likely to become increasingly common as glaciers shrink and some smaller ones disappear.
The Intergovernmental Panel on Climate Change was cautious on the potential impacts on monsoons. Some studies point to a potential weakening and some to strengthening as the monsoons are likely to become more variable in the future. “On the one hand we know that for a given monsoon wind pattern there will be more rain, but the monsoon wind pattern may weaken, so that net effect is uncertain,” said Toumi.
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Dr. Andy Turner is a lead author for the IPCC. He said: “Particularly for the monsoons in the south and south-east Asia, east Asia and the central Sahel [in Africa], monsoon precipitation is projected to increase by the end of the century.”
“However, near-term monsoon changes will be dominated by the effects of internal variability. Each additional degree of warming will exacerbate the frequency and severity of extreme events in monsoon regions, such as periods of heavy rainfall, flooding, and drought,” Turner, who is an associate professor in monsoon systems at Reading University stated.
Impact of climate change on Glaciers and livelihood
Water is a fundamental human need and hundreds of millions of people also depend directly on glaciers for their water and agriculture.
These are also likely to be among the water systems worst affected as Roger Braithwaite, an honorary senior research fellow at the University of Manchester, said: “Measurements show glaciers in many parts of the world currently have negative mass balances even with present global mean temperatures. Glaciers are therefore not ‘safe’ under the Paris agreement [which limits warming to 1.5C as an ambition, and 2C as an outer limit].”
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Speaking of glaciers worldwide, Meredith added that they have retreated since the 1990s; “this is unprecedented in at least two millennia, and is a clear signal of the impacts of global heating. For many communities downstream, high-mountain glaciers are fundamental to their way of life, providing a reliable source of freshwater for drinking and irrigating crops. As these glaciers continue to retreat, initially the stronger melt will cause a greater risk of floods, avalanches, and landslides – direct hazards for those living downstream.”
“In due course, the decrease in freshwater available will shift the risk to being that of drought. There are millions of people who live downstream of major mountain glacier systems such as the Himalayas; this is of extreme concern to their lives and livelihoods,” the science leader at the British Antarctic Survey said.
The Himalayas are important in regulating land-ocean temperatures, which then define the season’s rainfall mainly over India.
Impact on Water Systems
The landmark IPCC report contains more than 200 pages on the issue of changes to the planet’s natural rainfall patterns due to the impacts of climate change and a fuller discussion of the expected impacts of the climate crisis on the water will come next February.
It will be published in the second part of the report – the sixth from the world authority on climate science since 1988. However, the findings so far contain the starkest warning yet of the problems the world faces.
The impacts of water systems are already bringing devastation to millions of people around the world, worsening poverty, disrupting societies, and turning life into a daily struggle for some of the most vulnerable, said Jonathan Farr.
He is the senior policy analyst for climate change at the charity WaterAid who pointed to Lake Chilwa, which is central to the lives of 1.5 million people, saying “While its levels have always fluctuated, it’s now happening more frequently and to greater extremes, affecting the local communities.”
“Women, most often responsible for securing water for their families, can often queue at the borehole for many hours, sometimes through the night, waiting for the levels to refill to the point where they can draw water,” he spoke of Malawi’s second-biggest lake – Lake Chilwa after Lake Malawi.
Governments meeting for the UN Cop26 climate summit in Glasgow in November must take action not just on greenhouse gas emissions, but on providing funding for poor nations to adapt to the impacts of the climate crisis that are already being seen, Farr added.