Oceanography

Focus on greenhouse gases in the atmosphere has led to a lot of confusion among the public: bad storms are caused by global warming but a lack of warming is not.

There may be a reason things don't add up, according to a paper in Science. The circulation of the ocean plays an equally important role in regulating the earth's climate, it finds. In their study, the researchers say the major cooling of Earth and continental ice build-up in the Northern Hemisphere 2.7 million years ago coincided with a shift in the circulation of the ocean – which pulls in heat and carbon dioxide in the Atlantic and moves them through the deep ocean from north to south until it's released in the Pacific.


Though the continental United States hasn't had a major hurricane in almost 10 years, the rest of the world hasn't been so lucky. Japan just had a typhoon, India a cyclone, and, with Gonzalo, Bermuda is about to have its first major Atlantic hurricane in three years.

Hurricane Gonzalo has made the jump to major hurricane status and on
October
15th was a Category 4 storm on the Saffir-Simpson Hurricane Scale. NOAA's GOES-East satellite provided imagery of the storm. According to the National Hurricane Center, Gonzalo is the first category 4 hurricane in the Atlantic basin since Ophelia in 2011.


A new computer model has estimated ocean circulation during the last ice age, about 21,000 year ago, and believe that icebergs and meltwater from the North American ice sheet would have regularly reached South Carolina and even southern Florida.


Antarctic sea ice reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map sea ice extent in the late 1970s.

The Antarctic sea ice extent exceeded 7.72 million square miles (20 million square kilometers) for the first time since 1979, according to the National Snow and Ice Data Center. The ice extent stayed above this benchmark extent for several days. The average maximum extent between 1981 and 2010 was 7.23 million square miles (18.72 million square kilometers). 

Worth it for cheap cotton? Credit:so11e/flckr, CC BY-NC-ND

By Anson Mackay, University College London

The Aral Sea has reached a new low, literally and figuratively; new satellite images from NASA show that, for the first time in its recorded history, the largest basin has completely dried up.

Ice sheets were never simple. There is no magic knob that could be turned to optimize melting rates and movement, outside environmental press releases.

A new paper in Nature this week
shows that not only is meltwater not as simple as sometimes contended, we don't even know what we don't know. Observations of moulins (vertical conduits connecting water on top of the glacier down to the bed of the ice sheet) and boreholes in Greenland show that subglacial channels ameliorate the speedup caused by water delivery to the base of the ice sheet in the short term.


Farm runoff and urban pollution in the Hawaiian islands is causing sea turtle tumors, according to a study in PeerJ.

The paper by researchers at  Duke University, the University of Hawaii and the National Oceanic and Atmospheric Administration finds that nitrogen in the runoff ends up in algae that the turtles eat, promoting the formation of tumors on the animals' eyes, flippers and internal organs.


There is less saline in Nordic Seas but that can't be blamed on more Arctic waters due to global warming. Instead, it is that the Gulf Stream has provided less salt.

 The Nordic Seas have freshened substantially since 1950. This has happened at the same time as there has been observed increased river runoff and net ice melting in the Arctic. The concurrence of a less saline ocean and Arctic freshwater input has given the climate research community reason for concern, but a new study finds that the source of fresher Nordic Seas since 1950 is rooted in the saline Atlantic, as opposed to Arctic freshwater that is the common inference.

It may already be too late to stop Antarctic ice sliding into the ocean. Credit: EPA

By Eelco Rohling, University of Southampton

Ice sheets respond slowly to changes in climate, because they are so massive that they themselves dominate the climate conditions over and around them. But once they start flowing faster towards the shore and melting into the ocean the process takes centuries to reverse. Ice sheets are nature’s freight trains: tough to start moving, even harder to stop.

Ice ebbs and flows, that is no secret - but lost in claims that ice is as widespread as ever is the reality that it is now thinner, and the difference is so noticeable the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite can detect it.

The strength of gravity at Earth’s surface varies subtly from place to place owing to factors such as the planet’s rotation and the position of mountains and ocean trenches. Changes in the mass of large ice sheets can also cause small local variations in gravity.