During October and November 2008, some 150 scientists from 40 institutions in eight nations — including scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory — will take part in an international field experiment designed to make observations of critical components of the climate system of the southeastern Pacific.  Because elements of this system are poorly understood and poorly represented in global climate models, collecting real-time, complementary data from a variety of areas will go a long way toward improving scientists’ ability to use these models for making accurate predictions about Earth’s climate.

A total of five aircraft — including DOE’s G-1 Gulfstream research aircraft, operated by Pacific Northwest National Laboratory (PNNL) with instruments developed at both PNNL and Brookhaven — and two research ships will sample the lower atmosphere and upper ocean during the experiment.  Two sampling sites operated by research groups from Chile, Sweden, and the United States with conduct complementary sampling studies in the coastal region of Chile south of Santiago.

“We are motivated to participate in this study because the vast area of clouds in this region will provide an ideal laboratory for testing theories that have been developed at Brookhaven Lab regarding how precipitation forms in clouds and how aerosols affect cloud optical and microphysical properties,” said Brookhaven chemist Peter Daum, chief DOE scientist for the study.

The southeastern Pacific region is dominated by strong coastal upwelling, bringing cold, dense seawater from the deep ocean closer to the surface and resulting in extensive cold sea surface temperatures.  It is also home to the largest subtropical deck of low-lying stratocumulus clouds on Earth.

“These and other chemical and physical factors shape the regional climate and affect the global weather in ways that are poorly understood,” said C. Roberto Mechoso, a professor of atmospheric and oceanic sciences at the University of California, Los Angeles, who chairs the research program.  “Our research should produce a better understanding of the Southeast Pacific Ocean system, and improve our global computer climate models —which would lead to more confidence in climate forecasts, including predictions about global warming.”

Mechoso heads the scientific modeling arm of the research program, while Robert Wood, assistant professor of atmospheric sciences at the University of Washington, will lead the experimental field component.

Specifically, the scientists will focus on gaining a better understanding of:

* the processes that control the properties of stratocumulus clouds – including the influence of tiny aerosol particles emitted from smelters and volcanoes located on the South American continent

* the processes that control the transport of cold freshwater in the ocean

* the chemical and physical interactions between the lower atmosphere and upper ocean

The study is known as the Variability of the American Monsoon Systems’ (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex).  It is a component of a larger international climate study program, VOCALS.  The major goal of the VOCALS program is develop and promote scientific activities leading to improved understanding, model simulation, and predictions of the southeastern Pacific ocean-atmosphere-land climate system on day-to-day and year-to-year timescales.  The other major components of VOCALS are a modeling program ranging from local to global scales and a suite of extended observations from regular research cruises, instrumented moorings, and satellites.

The combination of intensive field measurements, long-term observations, and modeling will provide important insights that could directly benefit climate modeling, the researchers say.

In recent years, public discussion of climate change has included concerns that increased levels of carbon dioxide will contribute to global warming, which in turn may change the circulation in the earth’s oceans, with potentially disastrous consequences.

In a paper published today in the journal Science, researchers presented new data from their analysis of ice core samples and ocean deposits dating as far back as 90,000 years ago and suggest that warming, carbon dioxide levels and ocean currents are tightly inter-related.  These findings provide scientists with more data and insights into how these phenomena were connected in the past and may lead to a better understanding of future climate trends.

With support from the National Science Foundation, Jinho Ahn and Edward Brook, both geoscientists at Oregon State University, analyzed 390 ice core samples taken from Antarctic ice at Byrd Station.  The samples offered a snap shot of the Earth’s atmosphere and climate dating back between 20,000 and 90,000 years.  Sections of the samples were carefully crushed, releasing gases from bubbles that were frozen within the ice through the millennia.  These ancient gas samples were then analyzed to measure the levels of carbon dioxide contained in each one.

Ahn and Brook then compared the carbon dioxide levels from the ice samples with climate data from Greenland and Antarctica that reflected the approximate temperatures when the gases were trapped and with ocean sediments in Chile and the Iberian Peninsula.  Data from the sediments provided the scientists with an understanding of how fast or slow the ocean currents were in the North Atlantic and how well the Southern Ocean was stratified during these same time periods.

The researchers discovered that elevations in carbon dioxide levels were related to subsequent increases in the Earth’s temperature as well as reduced circulation of ocean currents in the North Atlantic.  The data also suggests that carbon dioxide levels increased along with the weakening of mixing of waters in the Southern Ocean.  This, the researchers say, may point to potential future scenario where global warming causes changes in ocean currents which in turn causes more carbon dioxide to enter the atmosphere, adding more greenhouse gas to an already warming climate.

Ahn and Brook state that a variety of factors may be at work in the future that alter the relationship between climate change and ocean currents.  One potential factor is that the levels of carbon dioxide in today’s atmosphere are much higher than they were during the period Ahn and Brook studied.  The researchers hope that future studies of the ancient gas from a newly drilled ice core may allow a higher resolution analysis and yield more details about the timing between CO2 levels and the temperature at the earth’s poles.

Many birds are arriving earlier each spring as temperatures warm along the East Coast of the United States.  However, the farther those birds journey, the less likely they are to keep pace with the rapidly changing climate.

Scientists at Boston University and the Manomet Center for Conservation Sciences analyzed changes in the timing of spring migrations of 32 species of birds along the coast of eastern Massachusetts since 1970.  Researchers at Manomet gathered this data by capturing birds in mist nets, attaching bands to their legs, and then releasing them.  Their findings, published in Global Change Biology, show that eight out of 32 bird species are passing by Cape Cod significantly earlier on their annual trek north than they were 38 years ago.  The reason?  Warming temperatures.  Temperatures in eastern Massachusetts have risen by 1.5 degrees Celsius (2.7 degrees Fahrenheit) since 1970.

Species, such as the swamp sparrow, that winter in the southern United States are generally keeping pace with warming temperatures and earlier leafing of trees.  They migrate earlier when temperatures are warm and later when spring is cool.

Birds that winter further south, like the great crested flycatcher, which spends its winters in South America, are slow to change, though.  Their migration times are not changing, despite the warming temperatures in New England.

There appears to be good reason for the difference between the shortand long-distance migrants.  Because temperatures are linked along much of the East Coast of the United States—an early spring in North Carolina is generally an early spring in Massachusetts—the short-distance migrants can gain insight into when it will be warm further north.  They can follow the flush of leaves and insects all the way to their breeding grounds each year.  Long-distance migrants, though, do not have any good cue for whether it will be an early or late spring on the northern stretches of their migrations.  Weather in South America has little to do with weather in New England.

Being slow to change in response to warming temperatures could have serious repercussions for long-distance migrant birds.  This same research group has shown that plants are blooming earlier in Massachusetts than they did in the past.  It appears that the short-distance migrants are keeping pace with this changing environment.  However, long-distance migrants are being left behind; as temperatures continue to warm, they will probably experience environments increasingly different from the ones for which they are adapted.  Other researchers have already noted that some long-distance migrant birds returning from African wintering areas to breed in Europe are now mistimed with their insect food supply.  The inability of some birds to adapt to rapid climate change may be an important factor in some of the declines among songbird populations that have been documented in recent years.

Two papers published in the journal Science today* by Microsoft Research ecologist Drew Purves together with research colleagues at Princeton University and universities in Madrid, Spain, highlight how an improved understanding of forest dynamics is needed to better predict environmental change. The research suggests that a new generation of realistic forest modelling, which is urgently needed and now within reach, will significantly improve an understanding of how forests work, how tree species respond to deforestation, and how forests impact climate regulation and environmental change.

The research points out that forest dynamics (how populations of trees interact with each other and the environment) remains the single most important outstanding component in fully understanding climate change. There trillions of trees on the planet, made up of more than 100,000 species, which contain as much carbon as is currently in the atmosphere and serve as home to two-thirds of the planet’s terrestrial biodiversity. However, while other climate change factors such as ocean dynamics are now well researched, the effects of changes to the world’s forests are still largely unknown.

The paper “Predictive Models of Forest Dynamics” by Purves and Princeton’s Stephen Pacala explores dynamic global vegetation models (DGVMs), which simulate the reaction of forests to past, present and future climate.

“DVGMs have shown that forests could be a crucial part of the way the Earth’s climate responds to man-made CO2 emissions, but insufficient understanding of forests, and insufficient data and computing power, have made their predictions highly uncertain,” Purves said. “This kind of uncertainty helps climate sceptics, who erroneously conclude that because the Earth is a complex but poorly understood system, we should not change our behaviour. However, we suggest that the convergence of recently developed mathematical models, improved data sources and new methods in computational data analysis could produce more realistic models. That would give us truly invaluable information to help manage the world’s forests and understand their impact on our climate.”

“Until now, one of the most important pieces of the climate change jigsaw has been missing,” Pacala said. “We argue that we can significantly further our understanding of forest dynamics if scientists work together to use new computational techniques and data sources — provided governments and others make more data available in useful forms. We feel that these discoveries could unlock the climate change mysteries of forests on a global scale in as little as five years.”

The second paper published in Science today, “Animal vs Wind Dispersal and the Robustness of Tree Species to Deforestation,” by Daniel Montoya from the Universidad de Alcalá in Madrid and Purves in Cambridge, with Miguel A. Rodríguez of the Universidad de Alcalá and Miguel A. Zavala of Centro de Investigación Forestal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CIFOR) in Madrid, examines what happens to individual tree species in the face of deforestation. Using data from nearly 90,000 survey plots in the Spanish peninsula, the paper found tree species that rely on wind to disperse seeds, rather than animals, are more vulnerable to deforestation.

Montoya said, “By applying various methods in computational data analysis to a large source of forest data, we have confirmed that, in Spain at least, plants with animal-dispersed seeds are less vulnerable to habitat loss, because animals provide trees with an intelligent dispersal mechanism, travelling and distributing seeds between areas of remaining forest. In contrast, a wind dispersal method is more susceptible to habitat loss, as seeds are more likely to fall in inhospitable environments. Using methods like this, conservationists can identify the species at most risk following deforestation, and use this knowledge to develop new strategies to mitigate the effects of widespread habitat loss and help to protect species diversity.”

The research also concludes that when no animal dispersers exist in the ecosystem, animal-dispersed tree species are the most vulnerable to deforestation. This means that protecting plant-animal interactions must also be a cornerstone of conservation policy, because the interactions not only create and maintain biodiversity, but also increase resistance to disturbances to the ecosystem.

Both papers underline the importance of forest dynamics in understanding and predicting climate change and biodiversity, highlighting the urgent need for additional study and resources. Purves said, “It is imperative that we create the tools and science to accurately understand the reaction of ecosystems to climate change and other forces — not just for plants and animals, but for our children and succeeding generations.”

This research is part of the recently established Computational Science Research at Microsoft Research Cambridge. This team of ecologists, biologists, neuroscientists, mathematicians and computer scientists is pioneering novel theoretical frameworks, computational tools and scientific methods to tackle the greatest scientific and societal challenges of this century, from climate change and declining biodiversity to understanding how living things work.

Forest management that favors single tree species and climate change are just two of the critical factors making forests throughout western North America more susceptible to infestation by bark beetles, according to an article published in the June 2008 BioScience. Bark beetle epidemics have become more extensive and frequent in recent years as winter temperatures have risen, and an eruption of mountain pine beetles is currently devastating lodgepole pines throughout the mountainous West.

The article, by Kenneth F. Raffa of the University of Wisconsin at Madison and colleagues at Colorado State University, the University of Idaho, and the US and Canadian Forest Services, stresses the complexity of the biological processes that determine when a bark beetle eruption will occur. When beetles bore through a tree’s bark, they release pheromones that summon other beetles to join the offensive. Trees counter attacks by exuding resin that can kill the invaders, but if too many beetles attack a weak tree, its defenses fail. The beetles then reproduce within its living tissues, with the help of colonizing fungi, and the tree is doomed. The condition and spacing of nearby trees and the local climate affect whether the beetle progeny released after a successful attack sustain an epidemic–which can kill a high proportion of the trees in an area and so alter the landscape for decades. Because many of the processes in an epidemic operate at different scales and turn on critical thresholds, prediction is a challenge. It is nonetheless clear that human activities can exacerbate bark beetle eruptions, which cause major economic losses and reduce forests’ ability to absorb carbon from the atmosphere.