Oceanography

A new aquifer in the Greenland Ice Sheet holds liquid water all year long in the otherwise perpetually frozen winter landscape. And it's big - 27,000 square miles. 

The reservoir is a "perennial firn aquifer" because water persists within the firn; layers of snow and ice that don't melt for at least one season. Researchers believe it figures significantly in understanding the contribution of snowmelt and ice melt to sea levels.  The Greenland Ice Sheet is vast, covering roughly the same area as the states of California, Nevada, Arizona, New Mexico, Colorado and Utah combined. The average thickness of the ice is 5,000 feet.  


There has been a snowfall decrease in Canada's subarctic regions and that has led to worrisome desiccation of the regions' lakes - this has happened in the past also, of course, but it was less noticeable. 

Researchers came to this conclusion after studying 70 lakes near Old Crow, Yukon, and Churchill, Manitoba. Most of the lakes studied are less than one metre deep. According to the analysis, more than half of those located on relatively flat terrain and surrounded by scrubby vegetation show signs of desiccation. The problem stems chiefly from a decline in meltwater; for instance, from 2010 to 2012 average winter precipitation in Churchill decreased by 76 mm compared to the averages recorded from 1971 to 2000.


Basic ocean conditions such as current directions and water temperature play a huge role in determining the behavior of young migrating salmon as they move from rivers and hit ocean waters for the first time -  and how the fish fare during their first few weeks in the ocean has a profound impact on species' ability to survive into adulthood.


Climate understanding of the past is based primarily on ice cores.  By studying information about Earth's climate and greenhouse gases  in past, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere and make better predictions about how climate will change in the future. 

Researcher have now identified regions in Antarctica they say could store information from as far back as 1.5 million years, almost twice as old as the oldest ice core drilled to date. 


Every organism needs nitrogen to survive and grow and many organisms do not have the ability to obtain nitrogen from molecular nitrogen (N2), the major component in the atmosphere because they lack the nitrogen fixation pathway and have to rely on supply of nitrogen that has been fixed by others.

The availability of fixed nitrogen, in the form of ammonium, nitrite and nitrate, consequently often limits primary production in the environment. That's one of the reasons why many fertilizers are rich in fixed nitrogen.


NASA is going to measure changes in the height of the Greenland Ice Sheet and surrounding Arctic sea ice produced by a single season of summer melt, which will give researchers a more comprehensive view of seasonal changes and provide context for measurements that will be gathered during NASA's ICESat-2 mission, which is scheduled for launch in 2016. 


After oxygen in the atmosphere and ocean rose about 600 million years ago, earth got the first proliferation of animal life. Between then and now, numerous short lived biotic events took place when oxygen concentrations in the ocean dipped episodically.


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.