Articles Tagged "Doug L. Hoffman"

It is well known that carbon dioxide cannot directly account for the observed increase in global temperature over the past century. This has led climate scientists to theorize that many feedback relationships exists within the climate system, serving to amplify the impact of rising CO2 levels. One of these is the impact of rising temperature on the ability of the ecosystem to absorb CO2. The temperature sensitivity of ecosystem respiratory processes (referred to as Q10) is a key determinant of the interaction between climate and the carbon cycle. New research, recently published in the journal Science, shows that the Q10 of ecosystem respiration is invariant with respect to mean annual temperature, and independent of the analyzed ecosystem type. This newly discovered temperature insensitivity suggests that climate sensitivity to CO2 is much smaller than assumed by climate models.

Climate sensitivity is generally given as how much temperature rise would result from a doubling of atmospheric CO2 levels. Using IPCC figures for radiative forcing, a doubling of CO2 would lead to a temperature rise of about half a degree (see “Another Look at Climate Sensitivity”). Yet the UN IPCC Fourth Assessment Report (AR4) gives a much higher value for climate sensitivity. It claims a 2°C to 4.5°C rise for a CO2 doubling, or from four to nine times higher than what is see in the real climate system. Why? Climate models assume that there are large positive feedbacks as Earth warms. Among these feedbacks is the impact of rising temperature on emission and absorption of CO2 by Earth's biota.

Accurately predicting future levels of atmospheric CO2 requires a clear understanding of how land and atmosphere exchange CO2. Each year, photosynthesizing land plants remove (fix) one in eight molecules of atmospheric CO2. Land plants and soil organisms return a similar amount of the dreaded greenhouse gas. The balance between removal and respiration determines whether terrestrial ecosystems are a net carbon sink or source. Two papers in the August 13, 2010, issue of Science bring a new understanding of land-atmosphere CO2 exchange.

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Through generous subsidies from the US government, secured by corn-belt politicians, 25% of America's corn (maize) crop is turned into ethanol for use in automobiles. Ignoring the negative impact this has on food production, agricultural runoff and land use, there is new talk of raising government mandated fuel mixture proportions to use even more ethanol. At the same time, the idea of turning farm and forest wastes into "cellulosic" ethanol, a biofuel to power cars and trucks continues to languish. Because of the ongoing economic slump, a plentiful supply of ethanol made from corn, and uncertainty among policymakers, companies have delayed plans to build commercial-scale cellulosic ethanol plants, some canceling them altogether. Evidently, even the hundreds of millions of dollars on offer from the Department of Energy (DOE) are not enough to lure investors to participate in this latest biofuel boondoggle. Industry understands what biofuel advocates do not—biofuels make no sense in terms of energy policy: neither environmentally nor economically. Instead of propping up wasteful and nonviable biofuel schemes, Congress should stop all biofuel subsidies and kill all ongoing ethanol projects.

Though the wrong headed “cap and trade” bill has been derailed in the US Senate, the specter of energy legislation is once again rising. As the energy debate heats back up, the journal Science has dedicated its August 13, 2010, issue to the subject of alternative energy. Writing in the introduction, David Malakoff, Jake Yeston, and Jesse Smith identified the heart of the alternative energy problem:

The end of the age of fossil fuels may be in sight, but what comes after is still a bit of a blur. There are numerous alternatives to coal, oil, and natural gas from electricity generated by solar farms to biofuels brewed from plants. Scaling up these alternative sources of energy, however, has proved a challenge.

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Much concern has been raised by climate scientists regarding ice loss from the world's two remaining continental ice sheets. Rapid loss of ice-mass from the glaciers of Greenland and Antarctica are cited as proof positive of global warming's onslaught. The latest measurements involve the use of satellite gravimetry, estimating the mass of terrain beneath by detecting slight changes in gravity as a satellite passes overhead. But gravity measurements of ice-mass loss are complicated by glacial isostatic adjustments—compensation for the rise or fall of the underlying crustal material. A new article in Nature Geoscience describes an innovative approach employed to derive ice-mass changes from GRACE data. The report suggests significantly smaller overall ice-mass losses than previous estimates.

The storage of water or ice on land—the presence of large bodies of water or glacial ice sheets—affect the Earth's gravitational field. This effect is detected by the NASA Gravity Recovery and Climate Experiment (GRACE) satellites. Twin satellites were launched in March 2002, to make detailed measurements of Earth's gravity field. Since then, GRACE has been used to study tectonic features, estimate ground water volumes and calculate the amount of ice contained in the Greenland and Antarctica ice sheets. However, other factors can contribute to the GRACE measurements than just the volume of ice in an ice sheet. These factors include the response of Earth's crust (the lithosphere) to past changes in ice load.

Desperate to put the bad days of Climategate behind them, climate scientists are pronouncing the matter over and done with. After all of the revelations and disclosures surrounding Climategate, and all of the public mea culpas, a change in attitude by those in the climate science community would be welcome. A turn to greater openness regarding methods and data, along with less overt political boosterism. But evidently, that is not in the cards. Starting off with an editorial titled “Climategate closed,” the journal Nature Geoscience presents a number of troubling statements from people involved with climate change. Though calling for scientists to “be humble,” the tone of the commentaries is that no wrong was really done and nothing has changed. The only change that needs to be made is making a greater effort to “inform” the public and skeptics. Clearly, climate scientists just don't get it—they cannot simply return to business as usual.

The Nature Geoscience editorial begins with the declaration: “the case of the alleged misbehaviour of climate researchers at the University of East Anglia is now closed.” This based on the three reports from independent investigations that concluded the scientific results produced at the University of East Anglia were sound, but that there are deficiencies in the transparency of climate research. Though admitting that more openness alone is unlikely to resolve tensions between scientists, the media and politicians—or between skeptics and alarmists (their term)--the editorial complains that critics are crying “whitewash.” Their only remedies are greater openness, flexibility and better presentation to the public:

Difficult as this may be, scientists have to maintain a disinterested perspective on the available information, be prepared to change their assessment when new facts come to light, and accept differences in opinion while taking counter-arguments seriously. Along with greater openness, a much more nuanced and multifaceted discussion of the physical aspects of climate change needs to be presented to the public to avoid future accusations of cliquiness and gatekeeping.

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For those who beleive in anthropogenic global warming, carbon dioxide is public enemy number one. They warn that CO2 must be avoided at all costs or Earth will heat up uncontrollably causing all sorts of ecological havoc. One proposal for avoiding global warming is the sequestration of CO2 by trapping it at combustion sites or extracting it directly from the air. Supposedly, such sequestration could help avoid a large rise in atmospheric CO2 from the use of fossil fuels, avoiding the hellish fate that surely awaits mankind otherwise. Referred to as carbon capture and storage (CCS), the coal industry has seized on sequestration as a way to get greens off their backs and stay in business. However, it is not clear how effective different types of sequestration and associated leakage are in the long term, or what their consequences might be. A recent paper takes a critical look at the sequestration option.

In an article in the June 27, 2010, issue of Nature Geoscience, “Long-term effectiveness and consequences of carbon dioxide sequestration,” Gary Shaffer, from the Department of Geophysics at the University of Concepcion in Chile, has provided a sobering look at carbon sequestration in its various guises. His analysis presents the results from projections over 100,000 years for five scenarios of carbon sequestration and leakage using an Earth system model. The research is described by the author in the paper as follows:

Massive application of carbon dioxide capture and storage (CCS) has become a prominent proposal for mitigating global warming1. Recent discussions of CCS have been centred on its motivation, feasibility and cost compared with other mitigation strategies. Concerns have also been raised about possible consequences of storing CO2 in the ocean and of leakage of CO2 stored in geological formations. Here I compare the effectiveness as well as Earth system consequences of CO2 leakage for sequestration in the ocean and in onshore and offshore geological formations. For this purpose I make long projections with the reduced-form, Danish Center for Earth System Science (DCESS) model.

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According to a new report in Nature Geoscience, scientists are beginning to realize that previously ignored aspects of the terrestrial biosphere can act as key regulators of atmospheric chemistry and climate. Not only that, changes in the biosphere can happen quickly—in the course of a few decades. “Although interactions between the carbon cycle and climate have been a central focus, other biogeochemical feedbacks could be as important in modulating future climate change,” states the report. Because a number of these feedbacks can have a cooling effect, the impact on global warming predictions could be earthshaking. The problem is, these feedbacks are only poorly understood and they are so interrelated that modeling them will be difficult, if not impossible.

......So, what are we to make of this new report, revealing a plethora of missing or previously ignored factors involved in climate regulation? From the levels of understanding shown in the figure above, it is clear that these factors are not well explained. When we stated in The Reslilient Earth that our knowledge of how climate works was sorely limited, the revelations made public in this report were only hinted at. Yet the Nature Geoscience report intimates that these processes and feedbacks are too important to ignore. In fact, the authors state that, “although interactions between the carbon cycle and climate have been a central focus, other biogeochemical feedbacks could be as important in modulating future climate change.”

Driven by a constantly expanding need for electricity, Chile is considering building seven new dams and a transmission line through its southern wilderness. This isolated land of condors and monkey puzzle trees is home to the third largest reserve of frozen freshwater in the world—the Southern Ice Field. Critics say the environmental risks have not been fully examined, and the risk to southern Chile's unique ecosystems is unacceptably high. Proponents of the dam project argue that hydroelectricity is a clean source of energy, just waiting to be tapped. Chile needs the 3500 MW/yr of power to meet its development goals and lacks indigenous oil or coal reserves. Moreover, the electricity from the dams would displace dirty generation, greatly reducing Chile's greenhouse gas emissions. Give all the benefits, why are so many people, within Chile and without, so opposed to the dams—opposed to the point of preferring new coal plants?

The HidroAysen project is the most ambitious dam proposal in the history of Chile. Along with proposing the construction of 5 dams on two of Patagonia's most pristine rivers, the Pascua and Baker, it plans on building a 2000 km high-voltage transmission line North to Santiago, creating the world's longest clear-cut. The proposed dams would flood rare temperate rainforests and some of Patagonia's best ranching lands. The rainforest areas that the dams and transmission lines would eliminate do not exist anywhere else on the planet—more than 50% of the plant species found in southern Chile are found nowhere else. Along with altering Chile's environment from the south to the Central Valley, the project threatens future damming of other rivers in Patagonia. Activists fear, that once the transmission line is in place, rivers such as the Puelo, Yelcho, Palena and the Futaleufu will also be scheduled for damming.

With virtually no coal, oil or natural gas, Chile imports more than 95% of its fossil fuels. Half the country's electricity comes from plants fueled by Argentinean oil or gas and Columbian coal. The other half comes from existing hydropower schemes, many of them in the central zone around the Biobío River. As a result, Chile has the most expensive energy in South America. Add to that often contentious relationships with neighboring countries and Chile's energy position is a disaster waiting to happen.

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Throughout Earth’s history, there is evidence of large carbon dioxide releases, greenhouse conditions, ocean acidification, and major changes in marine life. About 120 million years ago (mya), during the early part of the Cretaceous period, a series of massive volcanic eruptions pumped huge amounts of carbon dioxide into Earth's atmosphere. During the Aptian Oceanic Anoxic Event, atmospheric CO2 content rose to about twice today's level. Eventually, the oceans absorbed much of that CO2, which significantly increased the water's acidity. The change reduced the amount of calcium carbonate (CaCO3) in the water, making it difficult for creatures such as some kinds of plankton to form shells. But the plankton did not die out. In fact, the geological record indicates that ocean biota can adapt to CO2 concentrations as high as 2000 to 3000 ppm—five to eight times current levels.

Proxy evidence indicates that atmospheric CO2 concentrations were higher during long warm intervals in the geologic past, and that these conditions did not prevent the precipitation and accumulation CaCO3 as limestone. The accumulation of alkalinity from rock weathering, brought to the ocean by rivers, kept surface waters supersaturated. But these were gradual changes that lasted for extended periods of time, not perturbations. More rapid additions of CO2 during extreme events in Earth history include the end-permian mass extinction (251 mya), the Aptian Oceanic Anoxic Event 1a (OAE1a, 120 mya), and the paleocene-Eocene Thermal Maximum (PETM, 56 mya).

A team of paleontologists and geochemists have investigated how the high acidity affected the ancient marine ecosystem. Elisabetta Erba, Cinzia Bottini, Helmut J. Weissert, and Christina E. Keller examined fossils from ancient ocean sediments at two drill sites. One site is a now-above-ground formation in northern Italy, while the other lies in deep water in the mid-Pacific Ocean. “The Pacific Ocean was the only big ocean at that time,” Erba says. What they found is contained in a new paper, “Calcareous Nannoplankton Response to Surface-Water Acidification Around Oceanic Anoxic Event 1a,” in the July 23, 2010, issue of Science.

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The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) projected that global sea level will rise by up to 60 cm by 2100 due to global warming. The cause of this rise is twofold: expansion of ocean waters as they warm and additional water from glaciers melting. Despite nearly stable sea levels over the past 3,000 years, a number of low-lying and island nations have seized on the imminent flood as a reason to demand reparations from developed nations. In reality, most of the areas in the world that are suffering from inundation are threatened because of human actions, but not global warming. Damming and rerouting of rivers combined with over-pumping of ground water has led to subsidence in many areas—in other words, the seas are not rising, the land is sinking.

As reported in a review article in Science, authored by Robert J. Nicholls and Anny Cazenav, global sea levels have risen throughout the 20th century but key uncertainties remain. Mean sea level has remained nearly stable since the end of the last deglaciation. The rate of sea level rise over much of the last 6,000 years has been an almost-imperceptible 1.4 millimeters per year (about 6 inches per century). Based on tide gauge measurements, sea level has risen by an average of 1.7 ± 0.3 mm/year since 1950. Since the early 1990s, sea level rise (SLR) has been measured by high-precision altimeter satellites. Between 1993 and 2009, the mean rate of SLR was reported as 3.3 ± 0.4 mm/year. Naturally, to climate change alarmists, this suggests that SLR is accelerating because of warming climatic conditions.

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According to a recent paper, human actions may have caused Earth's climate to warm much earlier than previously expected. In an article to be published in Geophysical Research Letters and widely reported in the media, around 15,000 years ago, early hunters were a major factor in driving mammoths to extinction. Supposedly, this die-off had the side effect of heating up the planet. This is an interesting conjecture, since a letter just published in Nature Geocience reaches the opposite conclusion regarding climate and the mammoths' decline. This mammoth confusion illustrates the uncertain and even contradictory evidence that abounds in climate science.

In a new study, “Biophysical feedbacks between the Pleistocene mega-fauna extinction and climate: The first human-induced global warming?,” Chris Doughty, Adam Wolf, and Chris Field—all from the Carnegie Institution for Science—present an hypothesis explaining how neolithic hunters triggered global warming thousands of years before the invention of agriculture. You might recognize Field as the co-chair of the IPCC working group on impacts, adaptation and vulnerability. Here he participates in what The Economist called “some serious boffinry.”

Supposedly, the demise of leaf-chomping woolly mammoths at the hands of Homo sapiens contributed to the spread of dwarf birch trees in and around the Arctic. This proliferation of previously suppressed birch trees darkened the largely barren, reflective landscape and accelerated temperature rise across the polar north.

The northward spread of vegetation affected the climate because of the albedo effect: white snow and ice was replaced with darker land surfaces that absorbed more sunlight and created a self-repeating warming cycle. In the scenario proposed by Doughty et al., the process would have added to natural climate change, making it harder for mammoths to cope, and helping the birch spread further.

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