Wednesday, December 31, 2014

Yet another way humans are messing with the oceans: doubling nitrogen.

Humankind is messing with the ocean in entirely new ways.

On top of rising sea levels, ocean acidification and increasing temperatures, new research shows that we are changing the chemistry of the seas by doubling the Pacific's nitrogen.

(Image: Scientists aboard the research vessel Ka'imikai-O-Kanaloa study ocean chemistry as part of the Hawaii Ocean Time-series (HOT) Program in the North Pacific Ocean. Credit: Paul Lethaby, UH SOEST.)

The changes are due to human-generated nitrogen compounds that are changing the composition of the ocean from one that is short on nitrogen to one that has lots of nitroen and is short of phosphous. What that does is change the fertilization of the marine world.

What does it all mean? 

“The possible impacts of this anthropogenic perturbation on the open-ocean nitrogen cycle are numerous,” say the authors of a new paper, Increasing anthropogenic nitrogen in the North Pacific Ocean.

University of Hawai`i researcher David Karl joins co-authors Il-Nam Kim, Kitack Lee, Nicolas Gruber, John L. Bullister, Simon Yang and Tae-Wook Kim from Korea, Switzerland and NOAA in writing the paper, which appeared in the Nov. 28, 2014 issue of the journal Science.

The found that reactive nitrogen from fossil fuel burning and fertilizer that flows off agricultural and urban areas has doubled in the oceans during the past century. 

"This is a sobering result, one that I would not have predicted," said Karl.  "The North Pacific is so vast it is hard to imagine that humans could impact the natural nitrogen cycle."

This is not the first paper to see increasing levels of nitrogen, but is dramatic in part because it finds the increase is present throughout the ocean. Previous studies have found similar results nearer continents, and especially near Asia.

“The possible impacts of this anthropogenic perturbation on the open-ocean nitrogen cycle are numerous,” the paper says.

While it might seem that fertilizing the ocean could improve productivity, in fact it might change productivity in unanticipated ways—favoring species that like a higher nitrogen and lower phosphorus environment—with potentially unfavorable results.

“If similar trends are confirmed in the Atlantic and Indian Oceans, it would constitute another example of a global-scale alteration of the Earth system. Further, the findings of this study of the North Pacific highlight the need for greater controls on the emission of nitrogen compounds during combustion and agricultural processes.,” said a University of Hawai`ipress release on the research. 

The Swiss university ETH Zurich issued a press release that explains the results this way:

“When fossil fuels are burned at high temperatures, such as in coal and gas-fired power stations, nitrogen oxide and other reactive nitrogen compounds are formed and released into the atmosphere. Agricultural activities also have the same effect, when a part of the nitrogen found in fertiliser is lost into the atmosphere in the form of nitrogen oxide or ammonia. These emissions have risen dramatically in the past decades, particularly in East Asia where they have grown by 40 per cent in the past 10 years.”

How does the nitrogen get into the ocean? “The increase of the nitrate concentration in the North Pacific is mostly attributable to combustion processes in East Asia and to a lesser extent from agricultural activities in that region. The prevailing westerly winds carry these substances across the Pacific, where the rain flushes them from the air into the sea,” the Swiss university said.

Citation: I-N Kim, K Lee, N Gruber, D M Karl, J L Bullister, S Yang, T-W Kim (2014). Increasing anthropogenic nitrogen in the North Pacific Ocean. Science, 27 November 2014.

© Jan TenBruggencate 2014

Friday, December 26, 2014

Obesity and heart disease: mixed messages

Here’s another good reason to be very leery about second-hand reports about scientific study results.

Finally, it seems, new reports found some good news about being obese and having heart disease—or did they?

The studies suggest that people who suffer heart failure and who are obese are more likely to be alive a year later than thin folks are. Researchers call it the “obesity paradox.” Here’s one of those studies, in the December 2013 Journal of the American College of Cardiology.

Kinda seems like good news to those of us carrying a few extra pounds.

But almost every news medium and even Elsevier, a publisher of scientific papers, got this story wrong—suggesting that fat was protective against heart disease: “Is being overweight sometimes a good thing? Data suggest higher BMI protects against adverse cardiovascular outcomes, reports Mayo Clinic Proceedings.”

And that, of course, is wrong, wrong, dangerously wrong.

Here’s what the papers really say: If you already have heart disease, then you’re less likely to die soon if you’re too fat than if you’re too skinny.

The first study listed above says it clearly enough: “Although obesity is an independent risk factor for heart failure (HF), once HF is established, obesity is associated with lower mortality.”

The suggestion that obesity protects against heart disease “is potentially a dangerous message to promulgate from retrospective data in an environment saturated with an obesity epidemic and obesity-related conditions such as type 2 diabetes mellitus and coronary heart disease,” say these researchers in a Mayo Clinic journal

And the authors of still another paper say: “In our large, community-based sample, increased body-mass index was associated with an increased risk of heart failure. Given the high prevalence of obesity in the United States, strategies to promote optimal body weight may reduce the population burden of heart failure.” 

Being fat makes you twice as likely to get heart disease as people of healthy weight. But once you’re real sick, the fat folks with heart disease are 22-27 percent less likely to die in the short term. The obesity paradox discussion in popular media generally only looks at the second half of that equation.

It’s a little like cell phone company XXX saying, “If you’ll pay double for this $500 phone, I’ll give you $250 back and it’ll only cost you $750.” And then all the media saying you ought to choose cell company XXX because of the great rebate, not mentioning that you’re paying a 50 percent premium.

The American Heart Association notes that: “Obesity increases the risk for heart disease and stroke.” 
 And not only that, “but it harms more than just the heart and blood vessel system. It's also a major cause of gallstones, osteoarthritis and respiratory problems.”

A 2013 study confirms this: “Epidemiological studies have recently shown that obesity, and abdominal obesity in particular, is an independent risk factor for the development of heart failure.” 

The key statistics: nearly 70 percent of people with heart disease are obese, and, from this study by the Massachusetts Medical Society, “As compared with subjects with a normal body-mass index, obese subjects had a doubling of the risk of heart failure.”

And the bigger you get, the higher the risk: “A graded increase in the risk of heart failure was observed across categories of body-mass index.”

Why is this important for Hawai`i? The state’s obesity rate climbed from under 10 percent in 1990 to more than 20 percent now. 

While we have nearly the lowest obesity rate in the nation (21.8 percent, with only Colorado lower at 21.3), consider this: In 1991, no state in the U.S. had an obesity rate above 20 percent. Now they all do.

And while our rate in the Islands is comparatively low, it’s still dangerously high—in 2013 26.8 percent for men and 20.3 for women. In 2010, there were more than 78,000 people in the Islands with heart disease.

Sending mixed messages about the dangers of obesity is a danger in itself.

© Jan TenBruggencate 2014

Sunday, December 7, 2014

UH research: Warming's dark twin, acidification, eroding reefs.

Global warming’s dark twin, ocean acidification, is disrupting life in the oceans as dangerously as warming itself.

A recent study by University of Hawai`i researcher Nyssa Silbiger and her colleagues indicates that coral reefs are eroding as increasingly acid oceans eat away at their calcium carbonate structures.

(Image: MicroCT scan of experimental blocks reveals bioerosion scars. Credit: N Silbiger, M Riccio/Cornell.)

Corals are always in dynamic tension, as the building work of coral polyps is balanced against the destructive work of parrotfish and boring marine worms. But studies at the University of Hawai`i Institute of Marine Biology shows that acidification is tipping the scales toward destruction.

The paper, Reefs shift from net accretion to net erosion along a natural environmental gradient, by Silbiger, and co-researchers Òscar Guadayol, Florence I. M. Thomas and Megan J. Donahuein, is in the journal Marine Ecology Progress Series.

Researchers placed coral blocks onto the Kane`ohe Bay reef for a year, measuring them before and after by both weight and high-resolution computed tomography (CT) scans. Different parts of the reef have different levels of acidity, current flow, temperatures and other variables.

They found that the big predictor of coral erosion was acidity of the water. And since oceans are expected to continue to acidify from carbon-dioxide loading, that’s bad news for reefs.

And particularly bad news for reef areas subject to higher levels of acidity. The study found that rather than being uniform, acidity levels vary both in place and time.

“It was surprising to discover that small-scale changes in the environment can influence ecosystem-level reef processes. We saw changes in pH on the order of meters and those small pH changes drove the patterns in reef accretion-erosion,” Silbiger said in a news release.

What does it all mean?

“Our findings suggest that increases in reef erosion, combined with expected decreases in calcification, will accelerate the shift of coral reefs to an erosion-dominated system in a high-CO2 world. 

"This shift will make reefs increasingly susceptible to storm damage and sea-level rise, threatening the maintenance of the ecosystem services that coral reefs provide,” the researchers write.

Citation: NJ Silbiger, O Guadoyal, FIM Thomas, MJ Donahue (2014) Reefs shift from net accretion to net erosion along a natural environmental gradient. Marine Ecology Progress Series, vol. 515, doi: 10.3354/meps10999

© Jan TenBruggencate 2014

Friday, December 5, 2014

Hurricanes self-feed, sucking up El Nino heat from the deep ocean

It has long been asserted that El Nino events, warming the tropical Pacific as they do, promote hurricanes—but it may not occur as we’ve previously assumed.

(Image: Hurricane tracks shown in black in the eastern and central Pacific. Credit: Jin/SOEST.)

University of Hawai`i researchers have identified a two or three-season delay that explains a lot about hurricane behavior. The El Nino hot water sinks, moves in the ocean, and then surges back to the surface to fuel tropical cyclones.

And that’s important information in terms of predicting hurricane frequency and ferocity.

Fei-Fei Jin and Julien Boucharel, both of the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), published their study in the journal Nature. 

The researchers looked into the phenomenon in which El Nino is strongest in winter, but hurricane frequency picks up in the following summer and fall. At that time, most of the heated water from the El Nino is stored deep in the ocean of the eastern North Pacific.

But it may be that the activity of a young hurricane can suck that warm water to the surface, in essence finding the heat needed to fuel itself and supercharge the hurricane’s strength.

“We did not connect the discharged heat of El Niño to the fueling of hurricanes until recently, when we noticed another line of active research in the tropical cyclone community that clearly demonstrated that a strong hurricane is able to get its energy not only from the warm surface water, but also by causing warm, deep water – up to 100 meters deep – to upwell to the surface,” Jin said. He was quoted in a University of Hawai`i press release

Boucharel said that extra heat provides a lot of destructive energy.

“The Northeastern Pacific is a region normally without abundant subsurface heat. El Niño’s heat discharged into this region provides conditions to generate abnormal amount of intense hurricanes that may threaten Mexico, the southwest of the U.S. and the Hawaiian islands,” he said.

The authors wrote in the Nature paper: “we show that El Niño—the warm phase of an ENSO cycle—effectively discharges heat into the eastern North Pacific basin two to three seasons after its wintertime peak, leading to intensified TCs.”

They continue: “As a result of the time involved in ocean transport, El Niño’s equatorial subsurface ‘heat reservoir’, built up in boreal winter, appears in the eastern North Pacific several months later during peak (tropical cylone) season (boreal summer and autumn). 

"By means of this delayed ocean transport mechanism, ENSO provides an additional heat supply favourable for the formation of strong hurricanes.”

© Jan TenBruggencate 2014