THE WATER CYCLE

Global ecosystems and human civilization face a great challenge as a result of alterations to the global water cycle brought on by climate change.

Nevertheless, due to a lack of direct measurements, especially over the ocean where 77% and 85% of the world's precipitation and evaporation, respectively, occurs, it is challenging to estimate historical water cycle change.

The ocean's salinity is lowest in its hottest and coldest regions and greatest at intermediate temperatures due to freshwater flows between the air and the sea.

Researchers from the Barcelona Institute of Marine Sciences have made this unsettling discovery. They quantified the observed net poleward movement of freshwater in the Earth’s system from 1970 to 2014 and follow salinity variations in the warm, salty ocean component.

A rate of 34–62 milli-Sverdrup’s (mSv = 103 m3 s1) of poleward freshwater movement from warm to cold ocean areas has been observed throughout this period. With minimal influence from mixing and circulation, surface freshwater flow amplification in warm ocean locations causes an essentially comparable change in ocean freshwater content.

The consequence is that the historical surface flux amplification is smaller compared with observations. Their findings indicate a historical restriction on the movement of freshwater poleward, which will help to correct errors in climate models. This will lead to a rise in the frequency and severity of droughts, storms, and floods, which the UN's predict there may be some 560 catastrophes worldwide per year by 2030. This prediction is supported by the findings of this research.

This new study uses worldwide satellite data to examine the water cycle and the new dedicated satellite SWOT will assist even more.

In contrast, most other studies rely on buoys (‘salinity buoys’) that measure the amount of salt in the seas. It was because of this that they were able to establish a marked acceleration of the global water cycle.

In more concrete terms, when global temperatures rise, climatologists anticipate more ocean surface evaporation, which will increase the salinity of the ocean's top layer and contribute moisture to the atmosphere.

As a result, there will be more rain in some regions of the earth, diluting certain bodies of water and making them even less salty. The wet becomes wetter, and the dry becomes drier as a consequence.

The water cycle will be drastically altered as a result of further global warming, which will have a significant impact on our communities.

Storms and other floods, as well as droughts and water shortages, will become more severe.

According to the IPCC report from February 28, certain ecosystems will be affected more severely than others. For instance, the Mediterranean region or Central America would both become drier, while monsoon areas will have more rain.

Snowmelt may have started to accelerate due to this shift in the water cycle. In fact, the polar areas have seen an increase in precipitation.

Yet, as Estrella Olmedo, a mathematician from the Institute of Marine Sciences in Barcelona, says, "the evident fact that it is pouring instead of snowing accelerates the melting."

Extreme occurrences would become 14% more intense, according to the IPCC, even if world governments succeed in restricting global warming to a limit of 2°C (compared to 1900).

The effects of this transition may be severe, given there is currently a water deficit in over a quarter of the world.

In fact, decades of scientific study have shown the obvious link between greenhouse gas emissions and increasing global temperatures, which in turn causes the water cycle to intensify.

Slow decision-making in slow motion contributes to an uncontrollable cascade of events. The best course of action is to purchase a home that is more than 70 meters above sea level. (Seriously. This is the level advised if glaciers melt.)

Effective, protective, and cynical! You may say…

UN WATER SUMMIT – 22-24 March – NEW YORK

The UN Water Summit, led by the Government of the Netherlands took place in New York from 22–24 March. It will be the first time in more than 40 years that the UN has met to examine water issues; earlier attempts were thwarted by states that were averse to any type of global administration of the resource.

Henk Ovink, a special envoy for international water affairs for the Netherlands said: “If we are to have a hope of solving our climate crisis, our biodiversity crisis and other global challenges on food, energy and health, we need to radically change our approach in how we value and manage water. This is the best opportunity we have to put water at the center of global action to ensure people, crops and the environment continue to have the water they need.” [Turning the Tide – Web (low res) (watercommission.org)]

This is the UN agenda for the seven calls to action on water:

1. Manage the global water cycle as a global common good, to be protected collectively and in our shared interests.

2. Ensure safe and adequate water for every vulnerable group, and work with industry to scale up investment in water.

3. Stop underpricing water. Proper pricing and targeted support for the poor will enable water to be used more efficiently, more equitably, and more sustainably.

4. Reduce the more than $700bn of subsidies in agriculture and water each year, which often fuel excessive water consumption, and reduce leakage in water systems.

5. Establish ‘just water partnerships’ which can mobilise finance for low- and middleincome countries.

6. Take urgent action this decade on issues such as restoring wetlands and depleted groundwater resources; recycling the water used in industry; moving to precision agriculture that uses water more efficiently; and having companies report on their ‘water footprint’.

7. Reform the governance of water at an international level and including water in trade agreements. Governance must also take into account women, farmers, indigenous people and others in the frontline of water conservation.

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