Tuesday, April 30, 2013

Another study predicts a drier future for Hawai`i

Rainfall in the Islands has gradually dropped over the past three decades, and we seem to be facing an even more parched future.

University of Hawai`I and University of Colorado researchers, writing in the Journal of Geophysical Research, note that rainfall has slowly been declining since the late 1970s, and that the decline could continue through 2100.

The short version: Winters are drier than they used to be, and they will continue to be drier.

Hawai`i gets most of its rain in the winter, and the research they have done suggests the winter storms have been reducing in frequency.  The authors of the article are Oliver Elison Timm, Mami Takahashi, Thomas W. Giambelluca and Henry F. Diaz.

“For water resource and ecosystem management, and for other societal needs, we need to know whether this drying trend will continue this century,” said lead investigator Oliver Elison Timm at the International Pacific Research Center at UH Mānoa.

The team studied the large-scale weather patterns associated with heavy rain events.

“The patterns we saw did not surprise us,” said Oliver Elison Timm of the University of Hawai`i’s International Pacific Research Center. “For example, we found that the typical winter Kona storms with moist air-flow from the South often produce torrential rains in the islands.”

The large circulation patterns that create those downpours have been shifting, and reducing the number of rain events during the rainy season.

“We can’t predict individual rain events with our method,” said Thomas W. Giambelluca, Professor in the Department of Geography at UH Mānoa, but he said they can predict that drier winters and fewer winter downpours will be a pattern for most of the next century.

Another recent article doesn’t directly address the Hawaiian situation, but suggests in that in the tropics (We’re in the sub-tropics, so the data is not directly applicable.), areas that are already very wet will get wetter still. And areas that have significant ocean warming will also get wetter.

The article suggests more rain will occur with increasing warming in areas close to the equator. The authors of the piece are Ping Huang, Shang-Ping Xie,  Kaiming Hu, Gang Huang and Ronghui Huang, Shang-Ping Zie is with the University of Hawai`I’s International Pacific Research Center.

© Jan TenBruggencate 2013

Saturday, April 6, 2013

Climate research: Hawaii, Louisiana researchers reconcile ancientland-sea carbon differences

In the incredibly complex business of trying to understand past climate change by studying rocks and sediment cores, researchers keep fine-tuning.

That’s important because it helps understand how climate change will impact us in the future. 

(Image: University of Hawai`i-Manoa greenhouse where carbon uptake research was performed y varying atmospheric carbon-dioxide levels.  Credit: UH-Manoa.)

In an important piece of work, much of it done at University of Hawai`i greenhouses, researchers have helped understand why carbon isotope ratios seem to be laid down differently in land environments than in marine environments.

When science compares the amount of standard carbon, or carbon-12, to an isotope of carbon like carbon-13, a change the ratio is called an “excursion.”

When the amount of carbon dioxide in the atmosphere changes, the ratio of C12 to C13 changes as well.
There are bigger excursions in terrestrial rocks than marine rocks of the same age.

University of Hawai`i-Manoa geology professor A. Hope Jahren and University of Louisiana-Lafayette geologist Brian Schubert studied the issue and published their results  in an April 3 article in the scientific journal Nature Communications.  

Jahren grew plants in a Manoa greenhouse, where she varied the atmosphere to study them at different carbon-dioxide levels. She found that when carbon-dioxide is higher, the plants incorporate more C12 and a lower proportion of C13. In the ancient past, when plants died and became part of sedimentary rocks, that ratio was preserved—helping researchers calculate ancient carbon dioxide levels.

Carbon behaves differently in the oceans. When atmospheric carbon dioxide goes up, some of it is dissolved in the oceans, and impacts the carbon cycle there. But marine carbon use is complex and quite different from that on land.

“Our new model reconciles the differences based on the fundamentally different nature of carbon cycling on land compared to the ocean, injecting a more sophisticated view of ecology into current paleoclimatology,” Jahren said.

It means that science can now use the marine and terrestrial geologic records together as they study ancient climate and reconstruct ancient carbon dioxide levels. 

One of the scary pieces they draw out of the data: Schubert said that during a very warm climate period 55 million years ago, carbon dioxide levels were far lower than what we expect in the next couple of hundred years.

What could that mean? One presumes it could mean that climate will be hotter than anticipated in coming decades, that storm systems will change more dramatically, that sea levels will rise faster, that climate zones (think dust bowls) will move, and all the rest.

© 2013 Jan TenBruggencate

Citation: Schubert, B.A. and A.H. Jahren. Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels. Nat. Commun. doi: 10.1038/ncomms2659 (2013)

Monday, April 1, 2013

Hawai`i newborn hypothyroid cases linked to Fukushima radiation

There has been a lot of Hawai`i concern about radioactivity of marine debris from Japan’s March 2011 Fukushima nuclear plant meltdown, but the first actual physical impacts of the disaster have likely come from the sky.

The short version: Radiation in Hawai`i and the western states increased dramatically following  Fukushima, and shortly afterward, children born in these states displayed a statistically significant increase--16 percent-- in the rate of hypothyroidism, a disease that is associated with radiation.

Very soon after the radiation release, the radioactive particles were on their way across the Pacific on the winds, and very soon after that, newborns in Hawai`i and the western Mainland states began displaying possibly radiation-related thyroid disease.

A just-published, peer reviewed study shows that cases of hypothyroidism increased immediately following the Fukushima radiation release—in association with a dramatic increase in radioactivity levels.  

“There were increased concentrations of all beta-emitting radionuclides in the air during the six weeks following the beginning of Fukushima fallout. Compared to the same period a year earlier, the fallout increases were more than seven times greater in the five Pacific/West Coast States, compared to just over two times in the remainder of the US,” the paper says.

Of particular interest in this study was the isotope Iodine 131. Iodine is naturally drawn to the thyroid gland, and so is radioactive iodine. I-131 was virtually unknown in humans until the 1950s nuclear tests, at which time it was first isolated from adult thyroid glands. But the situation is far more serious for babies in utero.

“For decades radioactiveiodine has been recognized to cause adverse effects (including hypothyroidism) to the thyroid gland. The fetal thyroid, the first glandular structure to appear in the human embryo, begins to concentrate iodine and produce thyroid hormones by the 70th day of gestation,” wrote the authors of the paper, “Elevated airborne beta levels in Pacific/West Coast US States and trends in hypothyroidism among newborns after the Fukushima nuclear meltdown.”

The authors are Joseph J. Mangano and Janette D. Sherman of the Radiation and Public Health Project in New York. As they describe it, infants get the radioactive iodine from dairy products, and the cows get it “due to radioactive fallout deposition on forage.”

The Fukushima crisis created a pulse of radiation over the western U.S: “The largest amounts of radioactive fallout in the US environment from Fukushima occurred in late March and all of April 2011, before declining to levels typically recorded in 2010.”

The authors considered a number of other possible factors, including random variance in congential hypothyroidism numbers, but ultimately rejected them. “The statistical significance of the findings  make random yearly fluctuation unlikely as an explanation for the observed differences,” they wrote.

The authors are cautious with their data, and make the point that it’s early in the study of these connections: “The data presented in this paper, including both exposure levels and CH incidence, should be considered as preliminary. They require confirmation and expansion, including long-term follow-up of infants and other children. However, the current findings should be noted, and encourage the conduct of future analyses of health effects from exposures to Fukushima fallout.”

That said, their preliminary data seems compelling:

“Just days after the meltdowns, I-131 concentrations in US precipitation was measured up to 211 times above normal. Highest levels of I-131 and airborne gross beta were documented in the five US States on the Pacific Ocean. The number of congenital hypothyroid cases in these five states from March 17-December 31, 2011 was 16% greater than for the same period in 2010, compared to a 3% decline in 36 other US States. The greatest divergence in these two groups (+28%) occurred in the period March 17-June 30.”

While the American numbers are alarming, they are not nearly as serious as the impacts on Japanese children living near Fukushima, there, large proportions of children have displayed growths on their thyroid glands.  Here is one report on that phenomenon.

© Jan TenBruggencate 2013

This is the paper: J. Mangano, J. and D. Sherman, J. (2013) Elevated airborne beta levels in Pacific/West Coast US States and trends in hypothyroidism among newborns after the Fukushima nuclear meltdown. Open Journal of Pediatrics, 3, 1-9. doi: 10.4236/ojped.2013.31001.