oceans – The Green Tau

Counting on … day 206

17th December 2025

Only 2.5% of the Earth’s water is fresh water – the rest is salt water found in the seas and oceans.

Fresh water exists in two forms, blue water and green water.

Blue water is the water that is in rivers, lakes , underground aquifers and as frozen water in glaciers and ice sheets. Amazingly about 60% of blue water is locked away as ice.

Green water is the water stored in the soil and drawn up by plants.

Every year some 500,000km3 of water evaporates from the surface of the oceans, with 450,000km3 returning as precipitation directly back into the ocean(usually within a period of about 9 days) and 50,000km3 falling on land.

“The highest rate of evaporation from the oceans occurs in winter for both the Northern and Southern Hemispheres. The location of greatest evaporation is found on the east coasts of continents. This is due primarily to winter storms that move off the east coasts of continents, which tend to have strong winds. These winds help carry water vapor away from its source, thereby allowing more evaporation to take place.

“Another factor is the warm ocean currents that move pole-ward along the east coasts of continents. The cold winter-time air masses that move over the water allow for large differences in air and sea temperatures, so evaporation is also large. When these differences in air and sea temperatures are then combined with strong winds, it makes evaporation in these regions very efficient.” (1)

Water molecules from the ocean would struggle to reach the inner parts of the continents. Here precipitation is dependent on moisture that has been released by plants through evaporation, forming clouds etc. Plants provide about 70,000km3 of such precipitation. Vegetation cover is key to ensuring that precipitation spreads right across continents.

The other key source of water for inland areas is from melting snow and ice: high mountain regions capture precipitation and then release it throughout the year as meltwater-fed rivers. Water molecules that are exist within these frozen states may take a thousand years to complete the journey from precipitation to their return to the ocean! This is also highlights as we loose glaciers because of global warming, they will be hard to replace.

https://www.noaa.gov/jetstream/max-what-cycle

Counting on … day 203

12th December 2025

Can the acidification of the oceans be reversed? This from Biology Insights

“Reversing ocean acidification involves both natural and engineered approaches. The Earth has self-regulating mechanisms, such as the dissolution of calcium carbonate sediments on the ocean floor and the weathering of rocks on land. These processes release alkaline materials that neutralise acidity, but they operate over thousands of years and are too slow to counteract the current rapid changes.

“Scientists are exploring geoengineering techniques to accelerate this process. One proposal is ocean alkalinity enhancement, which adds alkaline substances like ground olivine or lime to seawater to increase its pH. This method seeks to speed up the natural weathering process to neutralise excess acidity.

“Other methods are more technologically intensive, such as electrochemical approaches that remove acidity directly from seawater. These systems would use electricity to manage ions and reduce acidity, but they face challenges of scale, cost, and energy requirements. The potential for unintended ecological side effects from these engineered solutions is not yet fully understood.” (1)

It is hard to imagine how either the geo engineering or the electrochemical solutions can work at scale. Ditto for proposals that carbon dioxide could be removed from the oceans and stored underground using carbon capture technology.

More promising are projects that focus on planting seaweeds such as kelp and sea grass which as they grow absorb carbon dioxide from the water. (2) At the same time such projects improve marine biodiversity, and indeed are often established as part of Marine Protected Areas. These project are often simply restoring ecosystems that have been degraded by human exploitation. Nevertheless even plants such as seagrass can struggle as temperatures rise and as ecosystems become more unstable. (3)

Therefore the most important way of protecting our oceans is to to reduce significantly and at speed the amount of carbon dioxide that we emit.

(3) https://www.mccip.org.uk/sites/default/files/2021-07/mccip-seagrass.pdf

Counting on … day 201

10th December 2025

When planetary boundaries are once crossed, it is still possible to reverse the situation and restore the balance of the Earth’s systems. However the effect of crossing a planetary boundary may irreversibly impact delicate parts of the Earth’s ecosystems such as coral reefs.

These reefs are important because:-

They protect shorelines from strong ocean currents and prevent coastal erosion
They provide sheltered waters for many species of sea life.
They filter polluted water ensuring clean water for marine life and clean beaches
They sustain local fishing based communities and especially those located on low-lying islands
They absorb carbon dioxide

Coral reefs are being damaged by the acidification of the oceans – the depletion of calcium in the structure weakens them. They are also damaged by rising ocean temperatures which stress the corals causing them to expel the symbiotic algae that enable them to feed and which give them their distinctive colours – this is called coral bleaching. (1)

The multiple causes of damage to the world’s coral reefs has destroyed such a proportion that their future is now jeopardised. These reefs are loss of coral reefs on this scale means that we have passed one of the Earth’s systems tipping points. (2)

In the Caribbean, coral reefs have decreased by 48% since 1980. (3)

Info graphic https://oceanservice.noaa.gov/facts/coralreef-climate.html

(1) https://www.wwf.org.uk/coral-reefs-and-climate-change

(2) https://global-tipping-points.org/case-studies/#coral

(3) https://www.theguardian.com/environment/2025/dec/09/caribbean-reefs-have-lost-48-of-hard-coral-since-1980-study-finds?CMP=Share_iOSApp_Other

Counting on … 187

14th November 2025

Not only have humans been adding excessive amounts of carbon dioxide to the atmosphere (largely though burning fossil fuels), we have also been destroying the Earth’s own ways of absorbing carbon dioxide. Two of the main ‘carbon sinks’ (as they are known) are forests, especially rain forests, and oceans.

Loss of rainforest in the Amazon continues to increase due to deforestation (principally clearing tree to grow other crops) and wild fires (which are increasing as temperatures rise and as droughts become more severe). (1)

It is sad to report that in the leaders’ summit in advance of COP30, the UK government determined not to help fund the Tropical Forests Forever Fund (TFFF). The TFFF aim is to raise $25 billion from developed countries attending COP30, which will underpin a $125 billion fund (p rest coming from private investors) to protect rainforests on both the Amazon and Congo. (3)

Oceans loose their ability to absorb carbon dioxide as they heat (warm water absorbs less CO2) (2)

and as flora and fauna are removed (from whales to sea grass) and from bottom trawling and mining which release previously absorbed CO2. (4)

To an extended protection of the oceans already exists via the 30 by 30 Kunming-Montreal Global Biodiversity Framework (GBF) where signatories agreed to protect and enhance the biodiversity of 30% of land and sea by 2030. (5) This will hopefully be further extended to include international waters that lie outside those waters controlled by individual nations with the High Seas Treaty. (6)

(1) https://news.mongabay.com/short-article/2025/06/climate-strikes-the-amazon-undermining-protection-efforts/

(2) https://news.climate.columbia.edu/2025/09/04/the-ocean-carbon-sink-is-ailing/

(3) https://www.theguardian.com/environment/2025/nov/05/uk-opts-out-of-flagship-fund-to-protect-amazon-and-other-threatened-tropical-forests

(4) https://www.southampton.ac.uk/publicpolicy/CFloor.page

(5) https://for-the-ocean.org/event/cop30/

(6) https://highseasalliance.org/treaty-negotiations/

Counting on … day 194

17th October 2024

Blue carbon is not just the carbon absorbed in the seas around our coasts. It is an ongoing process that encompasses oceans and deep seabeds. However scientists are concerned that the process is being adversely affected by rising temperatures.

“It begins each day at nightfall. As the light disappears, billions of zooplankton, crustaceans and other marine organisms rise to the ocean surface to feed on microscopic algae, returning to the depths at sunrise. The waste from this frenzy – Earth’s largest migration of creatures – sinks to the ocean floor, removing millions of tonnes of carbon from the atmosphere each year.

“This activity is one of thousands of natural processes that regulate the Earth’s climate. Together, the planet’s oceans, forests, soils and other natural carbon sinks absorb about half of all human emissions. But as the Earth heats up, scientists are increasingly concerned that those crucial processes are breaking down….

“Greenland’s glaciers and Arctic ice sheets are melting faster than expected, which is disrupting the Gulf Stream ocean current and slows the rate at which oceans absorb carbon. For the algae-eating zooplankton, melting sea ice is exposing them to more sunlight – a shift scientists say could keep them in the depths for longer, disrupting the vertical migration that stores carbon on the ocean floor.”

https://www.theguardian.com/environment/2024/oct/14/nature-carbon-sink-collapse-global-heating-models-emissions-targets-evidence-aoe?CMP=Share_iOSApp_Other