Reefs are made up of many coral species that live in a mutually beneficial symbiotic relationship with microscopically small algae hosted in their tissue. These symbiont algae produce sugars that contribute to the diet of the coral in return for shelter and nutrients that are vital for algal growth.
A symbiotic association is vulnerable to changes in environmental conditions, like seawater temperature. Heat-stress induced loss of the algal partners from the coral host can result in the often fatal process known as 'coral bleaching'.
A new species of algae has been discovered in reef corals of the Persian (Arabian) Gulf where it helps corals to survive seawater temperatures of up to 36 degrees Celsius - temperatures that would kill corals elsewhere.
Researchers have quantified how the Greenland Ice Sheet reacted to a warm period 8,000-5,000 years ago, when temperatures were 2-4 degrees C warmer than present and so could inform us what might happen if the same occurred now.
Dr. Nicolaj Krog Larsen, Aarhus University in Denmark and Professor Kurt Kjær, Natural History Museum of Denmark, ventured off to Greenland to investigate how fast the Greenland Ice Sheet reacted to past warming. Over six summers, they cored lakes in the ice-free land surrounding the ice sheet. The lakes act as a valuable archive as they store glacial meltwater sediments in periods where the ice is advanced. That way it is possible to study and precisely date periods in time when the ice was smaller than present.
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.