African governments, supported by the African Union (AU), are now in the process of drafting harmonized legislation in regard of the climate change presently sweeping the continent and giving Africa a common voice in the international arena of negotiations and compensations expected to come out of the Copenhagen Climate Change Summit in December.

Regional meetings are now ongoing to formulate a common African position for Copenhagen, and the African delegations are expected to look at US$70+ billion from the developed “polluters” whose previous actions are now adding to the African suffering previously wreaked on the continent through economic exploitation by the colonial and neo-imperial powers, stemming back to the slave trade.

East Africa, in particular, has been suffering of a region wide drought, spreading from the Horn of Africa across much of Ethiopia, Kenya and other countries and the ever faster and ever more intense cycles of drought and flooding have led to suggestions that this may be due to global warming and climate change.

Nairobi will be host city of a conference for African parliamentarians ahead of the Copenhagen meeting in mid-October and Nairobi-based United Nations Environment Programme (UNEP), Common Market for Eastern and Southern Africa (COMESA), a number of relevant non-governmental organizations (NGOs), bi- and multilateral partners and, notably, also the Kenya Wildlife Service are all putting their resources together to organize the gathering.

At least one Member of Parliament from the over 50 African countries part of the AU will attend and development partners, civil society and NGOs too are due for the meeting, where a comprehensive approach towards the climate change problems will be outlined.

Again, appropriately, it is Ethiopia presenting the African position in Copenhagen, as this Eastern African nation has in the past drawn the global spotlight over devastating and debilitating droughts, visiting upon Ethiopia like one of the ancient biblical plagues.

Africa presently has the lowest carbon footprint of all continents, but because of its geographical position is the most likely to suffer the severe weather fallout associated with climate change with a predicted 10 percent rise in average temperatures over the next 90 or so years.

The main targets for compensation will be the United States, the EU, China, India, and Russia. The latter three are expected to be the most obstinate and difficult ones to reach an agreement with.

Years have passed since Kyoto and these countries still resist a sizeable reduction of their carbon emissions and other pollution, to play a part in combating global warming. Considering this, even any compensation Africa is seeking to allow the continent to mitigate the climate change fallout and to develop environmentally friendly industries needed to provide employment for the large numbers of young Africans soon seeking to enter the workplace will be a challenge of its own herculean proportions.

Meanwhile, it was learned that Uganda is the first country to take advantage of the World Bank’s “Bio Carbon Fund,” which was set up, post Kyoto, to help countries to restore forests through reforestation projects. The National Forest Authority (NFA) is the lead partner in Uganda under a scheme aimed to ultimately bring forest cover back to 10s of thousands of hectares previously stripped of trees. Several hundred jobs are also expected to be created under the scheme, which laudably involved communities directly to ensure sustainability of the project.

NFA announced that they will use tropical hardwood trees, native trees and commercial tree species in areas where they are rolling out the project to ensure the longevity of the project while still, after some years, being able to use the “commercial” species for timber production. They have also pointed out that Uganda’s carbon trading position will be greatly enhanced, generating more funds to support the work NFA does nationwide. Watch this space.

David L. Chandler, MIT News Office

The Air Canada plane from Victoria to Toronto was cruising last year in clear skies; neither the pilots’ eyes nor the air traffic controllers’ radar screens saw any bad weather. Then, abruptly, the plane plummeted 2,000 feet in 15 seconds, and then another 2,000, before the pilot was able to regain control and level off.

The terrified passengers and crew — 10 of whom suffered injuries that would require hospital treatment — had experienced a phenomenon called an internal wave, something that is relatively unknown to the general public, and which is beginning to yield its secrets to scientists under new observational and modeling techniques.

Internal waves, which are prevalent in the oceans as well as in the atmosphere, are hidden from obvious view most of the time. But these colossal phenomena — a single wave can span 1,000 kilometers or more — can have profound effects on Earth’s climate as well as on drilling rigs, undersea cables and even vehicles such as submarines and, as those Air Canada passengers and crew can attest, to aircraft in flight.

Thomas Peacock, an associate professor of mechanical engineering at MIT, has been studying these waves for more than five years, and has uncovered important new details of how they form and propagate. His two latest papers on the subject are being published over the coming months in the Journal of Fluid Mechanics. One of these provides new insight into the forms of internal waves generated in the oceans, and the other helps explain the mystery of a narrow, focused beam of internal waves that recurs regularly twice a day – tied to the tides – in a channel in the Hawaiian Islands, but vanishes near the ocean surface.

Understanding these waves is important for models of climate change, because breaking internal waves in the ocean are believed to be a significant part of the mixing process by which warmer surface ocean water can be carried to the depths and colder water to the surface. This potentially makes them one of several important ocean mechanisms that impact the Earth’s climate.

Ron Prinn, director of MIT’s Center for the Science and Policy of Global Climate Change, says the mixing rate in the oceans — the rate at which warm surface waters get mixed with colder deep water and remove heat from the atmosphere — is one of the biggest remaining uncertainties in climate modeling, so understanding the mechanisms better could make a big difference in the accuracy of climate projections.

“It’s one of the outstanding problems” in climate modeling, says Raffaele Ferrari, professor of physical oceanography in the Department of Earth, Atmospheric and Planetary Sciences. He notes that although researchers have made great progress in understanding how internal waves are produced, when it comes to figuring out how they break — that is, how their energy is dissipated — “we can probably account for 20 percent, but we can’t account for the other 80 percent. It’s a missing link.”

Since such waves can disrupt both moving airplanes and underwater vehicles, and stationary equipment such as undersea drilling rigs and communications cables, this research could also have important practical consequences – at some point perhaps yielding improved ways of predicting the times and locations where they may occur. Because of that, Peacock’s work has drawn funding from the National Science Foundation, the MIT France Program and the Office of Naval Research.

The existence of internal waves has been known for more than a century, but exactly how they form and dissipate, and their effects on both natural and technological systems, are still being explored and are yielding new insights. Peacock and his students in the Experimental and Nonlinear Dynamics Lab (ENDLab) have made significant strides by coupling mathematical modeling of the behavior of these waves with laboratory experiments in wave tanks he has designed, and participation in field research at sea, in an effort to better understand not only how the waves form, but also how they then lose their energy. Bruce Sutherland, professor of physics at the University of Alberta, Canada, says that this combined approach is unique among climate scientists. “Such a holistic view has already benefited our understanding of climate,” he says, “through his studies of wave generation by tidal flow over ridges, and by the examination of the life-cycle of these waves emanating from sills and seamounts.”

The internal waves themselves are made up of moving regions of air or water that are more dense or less dense than their surroundings because of differences in temperature and, in the water, differences in salinity. In principle, they are similar to the familiar waves on the ocean’s surface, but because they occur within the water their visible manifestations are subtle, or sometimes nonexistent.

In the ocean, these waves form when tidal currents pass over an obstacle such as a submerged ocean ridge. “Cold, heavy water from the bottom gets pushed up over the ridge, and sets up a disturbance,” Peacock explains. They can also be generated by powerful storms, such as hurricanes, displacing the ocean surface. In the atmosphere, internal waves can be produced by thunderstorms and when air passes over a mountain range, in which case they are sometimes called “mountain waves.” It was just such a mountain wave, in the lee of the Rockies, that caused last year’s Air Canada plunge.

Besides his efforts to understand these waves, Peacock has been working to increase public understanding of these little-known yet widespread effects. To illustrate their power and immense scale, he plans to travel to Australia this fall to film a segment for a Discovery Channel program he is co-producing about internal waves; two segments in the South China Sea and off the West Coast of Australia have already been completed. He and the film crew hope to be able to catch an atmospheric internal wave that produces something called a Morning Glory cloud, in a location where they typically form at this time of year, and “surf” that wave in a glider. Because the long, narrow cylindrical cloud formation can span hundreds of miles, the popular Lonely Planet travel guide has described it as the most exciting natural phenomenon to observe in the sky next to a total eclipse.

“It’s a challenge, to try to be there when it happens,” he says. “But it will be a once-in-a-lifetime experience to surf the Morning Glory.”

The explosive eruption of Mt. Pinatubo in 1991 injected enough sulfur-containing compounds into the stratosphere to substantially reduce the amount of sunlight reaching Earth’s surface. In response to the increased reflectivity of the planet, the surface temperature cooled by about 0.3°C during 1992, with temperatures returning to their normal levels by 1994. But what happens when a much, much large eruption occurs?

Roughly 74,000 years ago, a “super-eruption” took place in Indonesia, the largest know eruption in the past 100,000 years. The Toba eruption was enormous, throwing out roughly 1000 times as much rock as the 1980 eruption of Mt. St. Helens (Fig. 1). Dust trapped in polar ice cores shows that ejected material spread around the globe, indicating that the eruption injected substantial material into the stratosphere, where it can strongly affect climate. How much and for how long the Toba eruption actually affected climate and life on the Earth’s surface has been the subject of intense debate.

Recently, we used state-of-the-art climate models to examine this question. Our study included climate models developed by the National Center for Atmospheric Research (NCAR) in Boulder, Col., and by the NASA Goddard Institute for Space Studies (GISS) in New York City. These are the same models used for climate projections of the near future in studies of global warming. In this case, we simulated the response to an enormous volcanic eruption to test how various processes might affect the climate response. Depending on the assumed size of the eruption and the processes included in the models, the maximum global mean cooling was 8-17°C. This is an enormous change, roughly 10-20 times the size of the warming since pre-industrial times and about the same magnitude as the transition to an ice age. Among the most interesting findings was that in response to the reduced sunlight able to penetrate the think blanket of ash and particles in the atmosphere, broadleaf evergreen trees and tropical deciduous trees virtually disappeared for several years. However, the Earth’s climate returned to near-normal conditions within a decade in most simulations.

Cooling of the Earth lasted longer in GISS model simulations including interactive chemistry in the atmosphere, however. This played an important role as the injection of volcanic material was so large in the Toba eruption that some chemical processes saturated, leading to a longer presence of sulfur-containing particles in the stratosphere. This extended the time of extreme planetary cooling so that in these simulations the Earth remained at least 10°C colder than normal for a full decade (Fig. 2).

An ice sheet did not begin to form in any of the simulations as the climate change did not persist for a long enough period. Hence the results do not support the theory that the super-eruption might have triggered an ice-age. However, a “volcanic winter” occurring suddenly and lasting a decade or two could still have devastating consequences on life at the surface, with abrupt massive decreases in food production and potential extinctions of some species. Indeed, there is some evidence for such extinctions and for the presence of a “genetic bottleneck” in human population coincident with the eruption. Our results thus suggest that the sudden and severe climate response to the Toba super-eruption may have wiped out a substantial portion of the world’s human population at that time.

Establishing a longer perspective for climate change is important in northern peatlands where carbon sequestration plays a major role in the global carbon cycle. Whether peatlands have always been the carbon sink they are today is critical for understanding future sinks and sources of carbon. Subarctic Alaskan peatlands are particularly sensitive to climate change, where alterations to the biogeochemical and hydrological cycles are affected by the vegetational shifts taking place. As part of a coastal regional Alaskan transect we analyzed a 2.5 meter sediment core at 2-cm intervals for fossil pollen, spores, and macrofossils over the last 14,000 years, utilizing plant macrofossils for accelerator mass spectrometry (AMS) carbon-14 dating. This record gives us the Kenai climate since the last ice age, which is then comparable to sites westward (Kodiak, the Alaskan Peninsula) and southeastward (Icy Cape, Yakutat).

Results show that peat initiation began on the Kenai Peninsula around 14,000 years ago, and cool temperatures resulted in shrubs dominating until the Holocene warming, which favored tree growth. Complexity in the Alaskan Younger Dryas cooling is indicated by the expansion of dwarf birch on the Kenai, while other Alaskan sites show declines in shrubs and increases in herbs. Possible explanations include either birch dominance due to increased snowfall which would have favored nutrient enrichment, or enhanced permafrost which may have created palsas and a drier habitat. A remarkable fern dominance that followed for about 3000 years (11,500-8500 years ago) shows high moisture in the region. This wetter interval is in contrast to drier conditions at Icy Cape and Yakutat to the southeast. This fern interval suggests a possible re-positioning of the Aleutian Low with increased rainfall, followed by a drier interval with high seasonality and enhanced glacial melt on the Kenai.

Figure 2. Pollen, spore, and LOI (a measurement of organic carbon) percentage stratigraphy from Swanson Fen. The vertical axis shows depth and time since deposition, with modern times at top and 14,000 years ago at bottom. Minor pollen taxa are magnified 10×. Dots adjacent to LOI indicate depths at which volcanic tephra was found.

These moisture shifts dramatically affected peat preservation, with enhanced peat preservation in the wetter interval and more decomposition in the drier regimes. Trees entered the local area as the climate warmed, and subsequent shifts in first cooling, then drying and volcanic activity between 5000 and 3500 years ago were followed by the cool, moist climate resulting in Neoglaciation up to the present. Mountain hemlock trees expanded after about 1500 years ago in response to cooler, moist conditions, a pattern typical of areas both to the west and southeast.

David L. Chandler, MIT News Office
August 17, 2009

Heavier rainstorms lie in our future. That’s the clear conclusion of a new MIT and Caltech study on the impact that global climate change will have on precipitation patterns.

But the increase in extreme downpours is not uniformly spread around the world, the analysis shows. While the pattern is clear and consistent outside of the tropics, climate models give conflicting results within the tropics and more research will be needed to determine the likely outcomes in tropical regions.

Overall, previous studies have shown that average annual precipitation will increase in both the deep tropics and in temperate zones, but will decrease in the subtropics. However, it’s important to know how the magnitude of extreme precipitation events will be affected, as these heavy downpours can lead to increased flooding and soil erosion.

It is the magnitude of these extreme events that was the subject of this new research, which will appear online in the Proceedings of the National Academy of Sciences during the week of Aug. 17. The report was written by Paul O’Gorman, assistant professor in the Department of Earth, Atmospheric and Planetary Sciences at MIT, and Tapio Schneider, professor of environmental science and engineering at Caltech.

Model simulations used in the study suggest that precipitation in extreme events will go up by about 5 to 6 percent for every one degree Celsius increase in temperature. Separate projections published earlier this year by MIT’s Joint Program on the Science and Policy of Global Change indicate that without rapid and massive policy changes, there is a median probability of global surface warming of 5.2 degrees Celsius by 2100, with a 90 percent probability range of 3.5 to 7.4 degrees.

Specialists in the field called the new report by O’Gorman and Schneider a significant advance. Richard Allan, a senior research fellow at the Environmental Systems Science Centre at Reading University in Britain, says, “O’Gorman’s analysis is an important step in understanding the physical basis for future increases in the most intense rainfall projected by climate models.” He adds, however, that “more work is required in reconciling these simulations with observed changes in extreme rainfall events.”

The basic underlying reason for the projected increase in precipitation is that warmer air can hold more water vapor. So as the climate heats up, “there will be more vapor in the atmosphere, which will lead to an increase in precipitation extremes,” O’Gorman says.

However, contrary to what might be expected, precipitation extremes do not increase at the same rate as the moisture capacity of the atmosphere. The extremes do go up, but not by as much as the total water vapor, he says. That is because water condenses out as rising air cools, but the rate of cooling for the rising air is less in a warmer climate, and this moderates the increase in precipitation, he says.

The reason the climate models are less consistent about what will happen to precipitation extremes in the tropics, O’Gorman explains, is that typical weather systems there fall below the size limitations of the models. While high and low pressure areas in temperate zones may span 1,000 kilometers, typical storm circulations in the tropics are too small for models to account for directly. To address that problem, O’Gorman and others are trying to run much smaller-scale, higher-resolution models for tropical areas.

Atmospheric carbon dioxide if coal emissions are phased out between 2010 and 2030.
Courtesy Hansen et al./Open Atmospheric Science Journal

A group of 10 prominent scientists says that the level of globe-warming carbon dioxide in the air has probably already reached a point where climate will change disastrously unless the level can be reduced in coming decades. The study is a departure from recent estimates that truly dangerous levels would be reached only later in this century.  The paper appears in the current edition of the Open Atmospheric Science Journal.

“There is a bright side to this conclusion,” says lead author James E. Hansen, director of the Goddard Institute for Space Studies, part of Columbia University’s Earth Institute. “”By following a path that leads to lower CO2, we can alleviate a number of problems that had begun to seem inevitable.” Hansen said these include expanding desertification, reduced food harvests, increased storm intensities, loss of coral reefs, and the disappearance of mountain glaciers that supply water to hundreds of millions of people.

The scientists say now that CO2 needs to be reduced to the level under which human civilization developed until the industrial age—about 350 parts per million (ppm)—to keep current warming trends from moving rapidly upward in coming years. The level is currently at 385 ppm, and rising about 2 ppm each year, mainly due to the burning of fossil fuels and incineration of forests. As a result, global temperatures have been creeping upward. The authors say that improved data on past climate changes, and the pace at which earth is changing now, especially in the polar regions, contributed to their conclusion. Among other things, ongoing observations of fast-melting ice masses that previously helped reflect solar radiation, and the release of stored-up “greenhouse” gases from warming soils and ocean waters, show that feedback processes previously thought to move slowly can occur within decades, not millennia, and thus warm the world further. Once CO2 gas is released, a large fraction of it stays in the air for hundreds of years.

The scientists, from the United States, United Kingdom and France, are optimistic that current atmospheric CO2 could be reduced if emissions from coal, the largest contributor, are largely phased out by 2030.  Use of unconventional fossil-fuel sources such as tar sands also would have to be minimized, they say. They predict that oil use will probably decline anyway as reserves shrink. So-called “geoengineering” solutions that would remove CO2 from the air have been proposed by others, but the group is skeptical; they estimate that artificially removing 50ppm of CO2 from the atmosphere would cost at least $20 trillion, or twice the current U.S. national debt. They suggest that reforestation of degraded land and use of more natural fertilizers could draw down CO2 by a similar amount.

“Humanity today, collectively, must face the uncomfortable fact that industrial civilization itself has become the principal driver of global climate,” says the paper.  “The greatest danger is continued ignorance and denial, which would make tragic consequences unavoidable.”

The other authors are Makiko Sato and Pushker Kharecha, both also of the Earth Institute; David Beerling of the University of Sheffield (UK); Robert Berner and Mark Pagani of Yale University; Valerie Masson-Delmotte of the University of Versailles (France); Maureen Raymo of Boston University; Dana Royer of Wesleyan University; and James Zachos of the University of California, Santa Cruz.