Darwin/Halifax:
The world’s largest reservoir is under your feet. Groundwater accounts for 97% of all usable fresh water. where is it In voids and cracks within rocks. We can see it when it is in springs, caves or when we pump it for use. While groundwater is often hidden, it underpins ecosystems around the world and is an important resource for people.
You might think that groundwater, being underground, would be protected from climate change. But not so now. As the atmosphere warms, more and more heat is penetrating underground. There is already enough evidence that the surface is warming. Temperature measurements taken in boreholes around the world show warming.
Our international team of scientists has combined their knowledge to model how groundwater will warm in the future. Under the realistic greenhouse gas emissions scenario, groundwater would be on average 2.1 °C warmer by 2100 than in 2000, with a projected average global atmospheric temperature increase of 2.7 °C.
These temperatures vary by region and are delayed by decades compared to the surface, as underground masses take time to heat up. Our results are globally accessible to everyone.
Why is it important?
You may be wondering what the consequences of hot groundwater will be. First, the good news, the heat rising below the land surface is trapping 25 times less energy than the ocean, but it is still significant. This heat is stored in layers tens of meters deep, making it easy to access. We can use this excess heat to continuously heat our homes from a few meters below the surface.
Heat can be extracted from renewable energy using heat pumps powered by electricity. Geothermal heat pumps are growing in popularity for space heating across Europe. Unfortunately, the bad news may outweigh the good news. Warming groundwater is harmful to the rich life found underground – and to the many plants and animals that depend on groundwater for their survival. Any change in temperature can disrupt the conditions to which they are adapted.
To date, the largest increase in groundwater temperature has occurred in parts of Russia, where surface temperatures have increased by more than 1.5 °C since 2000. In Australia, significant changes in groundwater temperature are expected in the shallowest layers. Groundwater regularly flows around the world to feed lakes and rivers as well as oceans, supporting a range of groundwater-dependent ecosystems.
If warm groundwater flows into your favorite river or lake, it will carry the extra heat from the sun. This can mean that it will be too hot for fish and other species to survive. Warm water also has less oxygen. Lack of oxygen in rivers and lakes has already become a major cause of mass fish kills, as we have seen recently in Australia’s Murray-Darling Basin.
Cold water species such as Atlantic salmon adapt to a window of water temperature provided by constant cold groundwater discharge. As this thermal refuse heats up, it will disrupt their reproductive cycle.
Groundwater is important
In many parts of the world, people rely on groundwater as the main source of drinking water. But the quality of the water we drink can deteriorate due to groundwater warming. Temperature affects everything from chemical reactions to microbial activity. For example, hot water can trigger more harmful reactions, where metals leach into the water. This is particularly worrisome in areas where access to clean drinking water is already limited.
Industries such as agriculture, manufacturing and energy generation largely depend on groundwater for their operations. If the groundwater they depend on becomes too warm or too polluted, it can disrupt their activities. Our study is global, but we need to know more about how groundwater is warming and what effects it might have locally. By studying how groundwater temperatures are changing over time and in different regions, we can better predict future trends and find strategies to adapt or mitigate the effects.
Global groundwater warming is a hidden but very important consequence of climate change. Although its effects will emerge late, its impact will be far-reaching and widespread. They will affect ecosystems, drinking water supplies and industries around the world.
(This news is not edited by the NDTV team. It is published directly from the syndicate feed.)