According to a new study published in Proceedings of the National Academy of Sciences, NOAA and NOAA-funded university scientists are closer to understanding why "red tides," called harmful algal blooms form. These toxic harmful algal blooms threaten marine ecosystems, human health, and cost local and regional economies millions of dollars annually through fishery closures and recreation and tourism losses.

The study looked at the impact that the cooperative interactions between marine microalgae and bacteria have on the growth of harmful algal blooms. Scientists have long recognized that certain species of bacteria are closely associated with the microalgae that form the harmful algal blooms, but didn’t understand why the blooms formed or what role the bacteria play.

The researchers found that certain species of bacteria form a mutually-beneficial relationship with the algae that promotes the growth of each. The bacteria release a chemical which helps the algae absorb iron, a critical nutrient for photosynthesis. The algae, in turn, release organic compounds to support the growth of the bacteria. The potential impacts of the study are extensive, and could result in improved modeling and forecasting of harmful algal blooms or potential strategies for prevention, according to William Sunda, Ph.D., of NOAA's Beaufort Laboratory, a co-author of the report.

"The results of the research have global implications," said Sunda. "If we can find a way to inhibit the bacteria we should be able to help communities around the world deal with problematic and costly algal blooms." The study also offers new insight for climate change models, since dimethylsulfide, a gas produced by the bloom-forming algae, plays a critical role in the process of cloud formation and the ability of clouds to reflect sunlight back into space. The degree to which light is reflected in turn influences solar heating of the Earth, affecting global climate.

Source: NOAA

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Recent tree loss, largely driven by climate stress, in forests around the world could portend increased tree mortality under climate change, according to a U.S. Geological Survey (USGS) report recently released online in the journal Forest Ecology and Management.

The USGS-led review suggests that many of the world's forests are sensitive to climate-related drought and heat stress, raising the concern that forests may become increasingly vulnerable to future mortality, even in environments that are not normally considered water-limited. The results suggest risks to ecosystem services that are valuable to forests and societies around the world.

"Trees can die much more quickly than they grow," said Craig D. Allen, USGS scientist and lead author of the report. "The widespread examples of drought and heat-induced tree mortality that we document illustrate how climate can drive abrupt, broad-scale impacts to essential forest services ranging from timber and protection of watersheds and biodiversity to recreational, aesthetic and spiritual benefits."

Although tree mortality episodes occur in the absence of climate change, the report's results are consistent with projections of future increases in tree mortality due to climate-related stresses. These heat and drought stresses could fundamentally alter the composition, structure and biogeography of forests in many regions, as well as affect how forests sequester carbon.

"This work by USGS underscores multiple risks that climate change poses to our forests and our world," said Secretary of the Interior Ken Salazar. "It also illuminates the importance of our efforts to develop practical, on-the-ground land management strategies that will help us adjust to the stresses that climate change is placing on our forests."

The report details 88 cases of significant tree mortality around the world associated with heat and drought since 1970, documenting climate-induced tree losses from Africa, Asia, Australia, Europe, North America and South America.

"From northern forests of spruce, pine or oak to tropical savannas and rainforests, many forest types appear vulnerable to such climate-driven mortality and to forest pests that are also highly sensitive to temperature," Allen said.

The report also identifies key information gaps and scientific uncertainties that currently hinder our ability to identify climate-related trends in tree mortality and to predict future losses in response to climate change, including lack of species-specific knowledge about tree water and temperature stress limits and the absence of a globally coordinated observation system.

However, in conjunction with other recent observational and experimental studies indicating that higher temperatures can drive increases in tree mortality, this article highlights risks that tree mortality could become more frequent and extensive as global climate change progresses.

Source: USGS

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Despite the fact that summer 2009 had more sea ice than in 2007 or 2008, scientists are seeing drastic changes in the region from just five years ago and at rates faster than anticipated. The findings were presented today in the annual update of the Arctic Report Card, a collaborative effort of 71 national and international scientists.

"The Arctic is a special and fragile place on this planet," said Jane Lubchenco, Ph.D., under secretary for oceans and atmosphere and NOAA administrator. "Climate change is happening faster in the Arctic than any other place on Earth - and with wide-ranging consequences. When I visited the northern corners of Alaska's Arctic region earlier this year, I saw an area abundant with natural resources, diverse wildlife, proud local and native peoples - and a most uncertain future. This year's Arctic Report Card underscores the urgency of reducing greenhouse gas pollution and adapting to climate changes already under way."

Among the changes highlighted in the 2009 update to the report card were:

A change in large scale wind patterns affected by the loss of summer sea ice,

The replacement of multi-year sea ice by first-year sea ice,

Warmer and fresher water in the upper ocean linked to new ice-free areas,

A continued loss of the Greenland ice sheet,

Less snow in North America and increased runoff in Siberia, and

The effect of the loss of sea ice on Arctic plant, animal, and fish species.

The Arctic Report Card is an annual assessment that was introduced by NOAA's Climate Program Office in 2006 and is an example of the suite of climate services to which NOAA contributes.

Scientific assessments are key to informing our understanding of climate – how and why it is changing and what the changing conditions mean to lives and livelihoods. The Arctic Report Card established a baseline of conditions in the region at the beginning of the 21st century and the annual updates track and monitor the often quickly-changing conditions in the Arctic. Using a color-coding system of red to indicate consistent evidence of warming and yellow to indicate there are mixed signals about warming from climate indicators and species, the report card is updated annually in October and tracks Arctic data in six categories: atmosphere, sea ice, biology, ocean, land, and conditions in Greenland.

"The Arctic we see today is very different from the Arctic we saw even five years ago," said Jackie Richter-Menge of the USACE Cold Regions Research and Engineering Laboratory in Hanover, N.H. and the report's chief technical editor and contributing author. "It's a warmer place with less thick and more mobile sea ice, warmer and fresher ocean water, and increased stress on caribou, reindeer, polar bears and walrus in some regions."

The 2009 update to the report card reflects the contributions of an international team of 71 researchers from countries that include the United States of America, Canada, Belgium, China, Denmark, Japan, The Netherlands, Russia, and the United Kingdom.

The Report Card can be found at http://www.arctic.noaa.gov/reportcard

Source: NOAA

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