Oceanography

Remote monitoring of large swathes of otherwise inaccessible ocean using satellites reveals an alarming picture: ocean acidity.

The Earth's oceans take up about a quarter of global CO2 emissions, which can turn the seawater more acidic, making it more difficult for some marine life to live.

Rising CO2 emissions, and the increasing acidity of seawater projected over the next century, has the potential to devastate some marine ecosystems, a food resource on which we rely, and so careful monitoring of changes in ocean acidity is crucial.


Total ocean alkalinity as viewed from space. Credit: Ifremer/ESA/CNES
There've been some recent environmental claims about methane seepage, flaming tapwater, but what were not staged have been due to nature.  It's a tale almost as old as earth.
Arctic sea ice extent plunged 2001 to 2007 but then rebounded between 2007 and 2013. Warming world or not, periods of no change - and rapid change - at the world's northern reaches are the new normal. And perhaps the old normal as well.

Natural ups and downs of temperature, wind and other factors mean that even as sea ice slowly melts, random weather can mask or enhance the long-term trend. For example, even in a warming world, there's still a one-in-three chance that any seven-year period would see no sea ice loss, such as in 2007-2013, a new analysis shows. And the chaotic nature of weather can also occasionally produce sea ice loss as rapid as that seen in 2001-2007, even though the long-term trend is slower.

GOCE gravity satellite. ESA

We might like to think of the earth as fixed and unmoving but that is not the case. Things are always shifting, even if we may not have noticed in the past.

Looks healthy, but still lacks the big predatory fish... how would it rate on the Promonitor Index? AF Johnson, CC BY-NC-SA

By Andrew Frederick Johnson, University of California, San Diego

As the Earth warms and glaciers all over the world begin to melt, the natural concern has been how all of that extra water will contribute to sea level rise.

Less considered is what happens to all of the organic carbon found in those glaciers when they melt. A new paper estimates what could happen if major ice sheets break down.

Glaciers and ice sheets contain about 70 percent of the Earth's freshwater and ongoing melting is a major contributor to sea level rise. But, glaciers also store organic carbon derived from both primary production on the glaciers and deposition of materials such as soot or other fossil fuel combustion byproducts.  



Scientists propose a new, potentially more accurate way, to measure the rate of sea level rise. Shutterstock

By Carling Hay, Harvard University

When you ask yourself what the biggest unanswered scientific questions are, “how did sea levels change over the past 100 years?” is unlikely to appear at the top of your list.


After mass bleaching in 1998, more than half of coral reefs in the Seychelles have slowly recovered. Nick Graham

By John Pandolfi, The University of Queensland

Coral reefs are the poster child for the damage people are doing to the world’s oceans. Overfishing, pollution and declining water quality have all taken their toll on reefs around the world. Perhaps the most famous example is Australia’s Great Barrier Reef, where half of the coral cover has disappeared over the past 25 years.

The change in global sea level rise since the beginning of the 20th century has been significantly larger than previous estimates according to new estimates in a new paper.

The paper, co-authored by Carling Hay, a Harvard post-doctoral fellow in the Department of Earth and Planetary Sciences (EPS), and Eric Morrow, a recent PhD graduate, says that previous estimates of global sea-level rise from 1900-1990 had been over-estimated by as much as 30 percent.  

But it confirms previous estimates of sea-level change since 1990, and that suggests that the rate of sea-level change is increasing more quickly than previously believed. 

The massive ice sheet that covers about 80 percent of Greenland is the largest single chunk of melting snow and ice in the world
and for that reason it is considered the biggest potential contributor to rising sea levels due to glacial meltwater in a warming world.

What gets the most media, and therefore a lot of research, attention is the ice sheet's aquamarine lakes -- bodies of meltwater that tend to abruptly drain -- and monster chunks of ice that slide into the ocean to become icebergs.