Antinuclear

Australian news, and some related international items

The melting of Antarctic ice is coming from warm waters underneath

Global warming is melting Antarctic ice from below Warming oceans melting Antarctic ice shelves could accelerate sea level rise, Guardian,  John Abraham, 9 May 18,  “……With global warming, both of the poles are warming quite quickly, and this warming is causing ice to melt in both regions. When we think of ice melting, we may think of it melting from above, as the ice is heated from the air, from sunlight, or from infrared energy from the atmosphere. But in truth, a lot of the melting comes from below. For instance, in the Antarctic, the ice shelves extend from the land out over the water. The bottom of the ice shelf is exposed to the ocean. If the ocean warms up, it can melt the underside of the shelf and cause it to thin or break off into the ocean.

 A new study, recently published in Science Advances, looked at these issues. One of the goals of this study was to better understand whether and how the waters underneath the shelf are changing. They had to deal with the buoyancy of the waters. We know that the saltier and colder water is, the denser it is.

Around Antarctica, water at the ocean surface cools down and becomes saltier. These combined effects make the surface waters sink down to the sea floor. But as ice melt increases, fresh water flows into the ocean and interrupts this buoyancy effect. This “freshening” of the water can slow down or shut down the vertical mixing of the ocean. When this happens, the cold waters at the surface cannot sink. The deeper waters retain their heat and melt the ice from below.

The study incorporated measurements of both temperature and salinity (saltiness) at three locations near the Dalton Iceberg Tongue on the Sabrina Coast in East Antarctica. The measurements covered approximately an entire year and gave direct evidence of seasonal variations to the buoyancy of the waters. The researchers showed that a really important component to water-flow patterns were ‘polynyas.’ These are regions of open water that are surrounded by ice, typically by land ice on one side and sea ice on the other side.

When waters from the polynya are cold and salty, the waters sink downwards and form a cold curtain around the ice shelf. However, when the waters are not salty (because fresh water is flowing into the polynya), this protective curtain is disrupted and warm waters can intrude from outside, leading to more ice melt.
Based on this study, we may see increased ice loss in the future – sort of a feedback loop. That concerns us because it will mean more sea level rise (which is already accelerating), and more damage to coastal communities. I asked the lead author, Alesandro Silvano about this work:

 Lead author Alesandro Silvano.

We found that freshwater from melting ice shelves is already enough to stop formation of cold and salty waters in some locations around Antarctica. This process causes warming and freshening of Antarctic waters. Ocean warming increases melting of the Antarctic Ice Sheet, causing sea level to rise. Freshening of Antarctic waters weakens the currents that trap heat and carbon dioxide in the ocean, affecting the global climate. In this way local changes in Antarctica can have global implications. Multiple sources of evidence exist now to show that these changes are happening. However, what will happen in Antarctica in the next decades and centuries remains unclear and needs to be understood.

This is just another reason to take scientists seriously and act to slow down climate change before it is too late.   https://www.theguardian.com/environment/climate-consensus-97-per-cent/2018/may/09/global-warming-is-melting-antarctic-ice-from-below

May 10, 2018 Posted by | AUSTRALIA - NATIONAL, climate change - global warming | Leave a comment

Turnbull’s election budget dumps on climate and renewables — RenewEconomy

Turnbull government finds $15 billion in short term tax handouts, and $140 billion in long term tax promises for the better off – but nothing on climate and renewables. Meanwhile, Australia misses out on global renewable jobs boom.

via Turnbull’s election budget dumps on climate and renewables — RenewEconomy

May 10, 2018 Posted by | Uncategorized | Leave a comment

Zibelman on changing energy market: “Get used to it” — RenewEconomy

Zibelman says critics need to get used to the fact that the energy market is changing, and it was underscored by AGL that said coal “is well and truly beaten out” by wind and solar.

via Zibelman on changing energy market: “Get used to it” — RenewEconomy

May 10, 2018 Posted by | Uncategorized | Leave a comment

SolarReserve may add 70MW solar farm to Port Augusta solar tower — RenewEconomy

SolarReserve may add up to 70MW of solar PV to world-leading solar tower and storage project to boost output at peak times and reduce purchases from grid.

via SolarReserve may add 70MW solar farm to Port Augusta solar tower — RenewEconomy

May 10, 2018 Posted by | Uncategorized | Leave a comment