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The Water Cycle Is Intensifying as the Climate Warms, IPCC Report Warns – That Means More Intense Storms and Flooding — Global Issues

Flood damage in Hagen, Germany. Credit: Bärwinkel, Klaus, Creative Commons.
  • Inter Press Service

Water-related hazards can be exceptionally destructive, and the impact of climate change on extreme water-related events like these is increasingly evident.

In a new international climate assessment released on August 9, 2021, the Intergovernmental Panel on Climate Change warns that the water cycle has intensified and will continue to intensify as the planet warms .

The report, on which I worked as a lead author, documents an increase in both wet extremes, including more intense precipitation over most areas, and dry extremes, including the drying up of the Mediterranean, southwestern Australia, southwestern South America, South Africa and western North America. It also shows that the wet and dry extremes will continue to increase with future warming.

Why is the water cycle intensifying?

Water circulates in the environment, moving between the atmosphere, ocean, land, and frozen water reservoirs. It can fall as rain or snow, seep into the ground, flow into a stream, reach the ocean, freeze or evaporate in the atmosphere. Plants also take water from the soil and release it through the transpiration of their leaves. In recent decades, there has been an overall increase in precipitation and evaporation rates.

A number of factors intensify the water cycle, but one of the most important is that warming temperatures increase the upper limit for the amount of moisture in the air. This increases the potential for more rain.

This aspect of climate change is confirmed in all our data sources: it is expected from basic physics, projected by computer models, and it already appears in observational data as a general increase in rainfall intensity with warming temperatures.

Understanding this and other changes in the water cycle is important for more than preparing for disasters. Water is an essential resource for all ecosystems and human societies, and in particular agriculture.

What does this mean for the future?

An intensifying water cycle means that wet and dry extremes and general variability in the water cycle will increase, but not uniformly around the world.

Precipitation intensity is expected to increase over most land areas, but the largest increases in drought are expected in the Mediterranean, southwestern South America and western North America.

Globally, daily extreme precipitation is likely to increase by about 7% for every degree Celsius (1.8 degrees Fahrenheit) that global temperatures rise.

Many other important aspects of the water cycle will also change in addition to extremes as global temperatures rise, the report says, including shrinking mountain glaciers, decreasing duration of seasonal snow cover, Earlier snowmelt and contrasting changes in monsoon rains in different regions, which will impact the water resources of billions of people.

What can be done?

A common theme across all of these aspects of the water cycle is that higher greenhouse gas emissions lead to greater impacts.

The IPCC does not make policy recommendations. Instead, it provides the scientific information necessary to carefully assess policy choices. The results show what the implications of the different choices may be.

One thing the scientific evidence in the report is making clear to world leaders is that limiting global warming to the Paris Agreement target of 1.5C (2.7F) will require immediate, rapid and large-scale reductions. greenhouse gas emissions.

Regardless of any specific target, it is clear that the severity of climate change impacts is closely related to greenhouse gas emissions: reducing emissions will reduce impacts. Every fraction of a degree counts.

Mathew Barlow, professor of climatology, University of Massachusetts Lowell

This article is republished from The Conversation under a Creative Commons license. Read the original article.

© Inter Press Service (2021) – All rights reservedOriginal source: Inter Press Service

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