Oceanography

With 99% of the Earth's water unused, it might not seem like there could be a water scarcity issue, but water tends to be boom and bust. Many of the poorest regions don't have access to potable water and new estimates by the Potsdam Institute for Climate Impact Research (PIK) if temperatures warm due to climate change.


Huge ice channels almost as tall as the  Eiffel tower have been discovered beneath a floating ice shelf in Antarctica. They are 250 meters high, stretch hundreds of kilometers along the ice shelf, and likely influence the stability of the ice shelf.

The scientists used satellite images and airborne radar measurements to reveal the channels under the ice shelf. The channels can be seen on the surface of the ice shelf, as well as underneath, because the ice floats at a different height depending on its thickness.  


New evidence suggests than no continental ice sheet formed during the Late Cretaceous Period more than 90 million years ago, when the climate was much warmer than it is today, though it has been commonly believed to have happened that way. 


Mild winters in Northern Europe are thanks to the Gulf Stream, which makes up part of those ocean currents spanning the globe that have always impacted the climate.

Yet our climate is also influenced by huge eddies, black holes of turbulence over 90 miles in diameter, that rotate and drift across the ocean. Their number is reportedly on the rise in the Southern Ocean, increasing the northward transport of warm and salty water. A good thing, because this could moderate the negative impact of melting sea ice in a warming climate. 


The ice sheet on West Antarctica just got a little older - 20 million years or so.

The findings indicate that ice sheets first grew on the West Antarctic subcontinent at the start of a global transition from warm greenhouse conditions to a cool icehouse climate 34 million years ago. Previous computer simulations were unable to produce the amount of ice that geological records suggest existed at that time because neighboring East Antarctica alone could not support it.


By analyzing a 150-year-old moss bank on the Antarctic Peninsula, researchers describe an unprecedented rate of ecological change since the 1960s, driven by warming temperatures. 

The researchers looked to the Antarctic Peninsula because it is one of the most rapidly warming regions on Earth; annual temperatures there have increased by up to 0.56°C per decade since the 1950s. There they found a moss bank that has been slowly growing at the top surface and accumulating peat material since it first established in about 1860. By analyzing core samples of that moss bank, they were able to characterize the growth and activity of the moss and microbes over time. 


The annual melting of sea ice in the Arctic is approaching its yearly "minimum," the time when the floating ice cap covers less of the Arctic Ocean than at any other period during the year, and there is some good news -   this year's summer low is not going to be too bad. 

The concerning news is that this year's melt rates are in line with the sustained decline of the Arctic ice cover observed by NASA and other satellites over the last several decades.


A recent review of research on the response of plants, marine life and animals to declining sea ice in the Arctic found that sea ice decline and warming trends are changing the vegetation in nearby arctic coastal areas.


The Earth has periodic ice ages - every 100,000 years, give or take, and the ice ages last far longer than the warm periods.

In the last century, scientists determined that Earth's ice ages were determined by the wobbling of the planet's orbit, which changes its orientation to the sun and affects the amount of sunlight reaching higher latitudes, particularly the polar regions. The Northern Hemisphere's last ice age ended about 20,000 years ago and then the ice age in the Southern Hemisphere ended about 2,000 years later, suggesting that the south was responding to warming in the north.

 But new research says that Antarctic warming began at least two, and perhaps four, millennia earlier than previously thought.


A year-round ice-free Arctic Ocean surface could explain why the Earth of the Pliocene Epoch had the levels of carbon dioxide in the atmosphere that we have today, but we remain 3 to 9 degrees cooler than the Earth was then.