(Press-News.org) Hydrofluorocarbons (HFCs), which have been used in recent years in increasing quantities as substitutes for CFCs, are also climatically very active and many are also extremely long-lived. In the renowned journal Science an international team of researchers recommends that the most potent of these gases also be regulated. This could save the positive «side effect» of the Montreal Protocol for the global climate.
It is regarded as the most successful international environmental agreement and has, to date, been ratified by 196 countries – the Montreal Protocol on Substances That Deplete the Ozone Layer. As a result, CFCs and ozone «killers» will gradually disappear from the atmosphere over the coming decades. And because many of these substances are also very active greenhouse gases, the Earth's climate will profit from the sinking concentrations too.
So far, so good. In many processes where previously CFCs were used, these are now being increasingly substituted by fluorinated compounds such as HFCs (which, simply put, are similar substances to CFCs but do not contain chlorine and do not deplete stratospheric ozone). They are used as cooling agents in air conditioning plants and refrigerators, as propellants in aerosol cans, as solvents and as foaming agents in the manufacture of foam products. However, there is a downside to the use of HFCs – they are also very potent greenhouse gases. HFC-134a, also known as R-134a, for example, which is used in automobile air conditioning units, is 1430 more active than the «classic» greenhouse gas carbon dioxide (CO2).
International environmental agreements can also have unwanted side effects
The reduction of greenhouse gas emissions is covered by the Kyoto Protocol. This agreement is, however, not binding for the world's largest emitter of greenhouse gases, the USA (which has never ratified the protocol), nor for threshold and developing countries. In addition the Kyoto Protocol is currently limited to the period from 2000 to 2012. No agreement has yet been reached on extending it. What this means is that the significant increase in global emissions of HFCs seen over the past few years will soon negate the positive effects on climate brought by the Montreal protocol's CFC phase-out.
This link is shown by an analysis published in the latest issue of Science. An international team of researchers, headed by Holland's Guus Velders and including the chemistry Nobel laureate Mario Molina and Empa researcher Stefan Reimann, investigated the unintentional (positive) climate effects resulting from the Montreal Protocol. Since the year 2000 the radiative forcing (a measure of the effect on the climate of chemical substances) of all ozone-depleting substances including CFCs has remained at a more or less constant value of 0.32 W/m2, compared to a value of 1.5 W/m2 for CO2. Had the Montreal Protocol recommendations not been implemented, today's value would be approximately double this figure, i.e.
0.65 W/m2. Putting things another way, the CFC ban has prevented the equivalent of 10 billion tonnes of CO2 being emitted into the atmosphere in 2010, five times the annual reduction target set by the Kyoto Protocol.
Velders, Reimann and their co-authors fear that this positive effect will soon be negated by HFC emissions, which are currently increasing at 10 to 15% annually. In their article they state that «the HFC contribution to climate change can be viewed as an unintended negative side effect» of the Montreal Protocol. At the moment the effect is still small – about 0.012 W/m2 for all CFC substitutes combined. But it is beyond question that radiative forcing due to HFCs will rise significantly in future as a result of increasing demand and production for these substances, above all in threshold and developing countries. The atmospheric scientists estimate that this value will rise to between 0.25 und 0.4 W/m2 by the year 2050. The greatest problem is presented by saturated HFCs, which are extremely stable and survive in the atmosphere for up to 50 years, exhibiting a long-term global warming potential of up to 4000 times higher than CO2. For Empa researcher Reimann the situation is clear: «Long-lived HFCs should no longer be used in these quantities.»
A «simple» solution: expanding the scope of the Montreal Protocol
Among other things, the scientists recommend modifying the Montreal protocol so that it also covers the use of long-lived HFCs. Such proposals have already been tabled in previous years by various countries including the USA. «Since it is it is as a result of the Montreal protocol that these substances are being manufactured in increasing amounts, they could be included in the agreement too, so their use can be regulated as well», maintains Reimann. A stepwise phase-out of HFCs is technically feasible since, according to Reimann, chemical and technological alternatives are already available. In the USA for example refrigerators are cooled using HFC-134a; in Switzerland the use of this substance in refrigerators is banned and climate neutral hydrocarbons are used instead.
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Pediatric cardiology researchers and clinicians from almost 50 centers from across the U.S. and around the world are gathering at the Cardiology 2012 Conference sponsored by The Children's Hospital of Philadelphia on Feb. 22-26 in Orlando, Fla. The news briefs below summarize 11 research abstracts selected by the conference organizers as featured presentations. The researchers leading these presentations comprise 6 physicians and 5 nurses.
New Early Warning Algorithm Detects Children's Early Cardiac Deterioration Before Inpatient Arrest
Most cardiopulmonary arrests in ...
A controversial bill that would make big changes to Florida's car insurance coverage system should soon be on its way to a vote by the full House after getting the OK from the third and final committee to review it, according to OnlineAutoInsurance.com.
If the bill is signed into law, drivers who go to run their next Florida insurance quote comparison could be in for a bit of a surprise.
That's because the bill would, among other things, nix the current system in which motorists rely on personal injury protection (PIP) policies to pay for their medical bills following ...
When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale.
It weighed in at around 12 pounds--and it was destined to get much smaller over the ensuing millennia.
Sifrhippus lived during the Paleocene-Eocene Thermal Maximum (PETM), a 175,000-year interval of time some 56 million years ago in which average global temperatures rose by about 10 degrees Fahrenheit.
The change was caused by the release of vast amounts of carbon into the atmosphere and ...
A life cycle assessment of growing crops for fuel as opposed to refining and using fossil fuels has revealed that substitution of gasoline by bioethanol converted from energy crops has considerable potential for rendering our society more sustainable, according to a Japanese study published in the International Journal of Foresight and Innovation Policy.
Kiyotada Hayashi of the National Agriculture and Food Research Organisation in Tsukuba and colleagues explain how biomass derived from sugarcane, sugar beet and other crops, has emerged as one of the most promising renewable ...
New research from the University of Calgary's Hotchkiss Brain Institute (HBI) shows that using a CT (computerised tomography) scan, doctors can predict if patients who have had a transient ischemic attack (TIA) or minor stroke, with neurological symptoms such as weakness or speech issues, are at risk for another more severe stroke. This vital information can help doctors decide if stronger medications should be used to prevent future episodes, or if a patient can be safely sent home.
Currently, doctors can use a brain MRI (magnetic resonance imaging) scan to predict ...
In the crash-car derby between heavy and light isotopes vying for the coolest spots as magma turns to solid rock, weightier isotopes have an edge, research led by Case Western Reserve University shows.
This tiny detail may offer clues to how igneous rocks form.
As molten rock cools along a gradient, atoms want to move towards the cool end. This happens because hotter atoms move faster than cooler atoms and, therefore, hotter atoms move to the cool region faster than the cooler atoms move to the hot region.
Although all isotopes of the same element want to move towards ...
From spaghetti-like sea anemones to blobby jellyfish to filigreed oak trees, each species in nature is characterized by a unique size and shape. But the evolutionary changes that produce the seemingly limitless diversity of shapes and sizes of organisms on Earth largely remains a mystery. Nevertheless, a better understanding of how cells grow and enable organisms to assume their characteristic sizes and shapes could shed light on diseases that involve cell growth, including cancer and diabetes.
Providing new information about the evolution of the diversity of sizes and ...
For decades, scientists have understood that there is a genetic component to intelligence, but a new Harvard study has found both that most of the genes thought to be linked to intelligence are probably not in fact related to it, and identifying intelligence's specific genetic roots may still be a long way off.
Led by David I. Laibson '88, the Robert I. Goldman Professor of Economics, and Christopher F. Chabris '88, PhD '99, Assistant Professor of Psychology at Union College, a team of researchers examined a dozen genes using large data sets that included both intelligence ...
PHILADELPHIA -- Would you be able to find an automated external defibrillator if someone's life depended on it? Despite an estimated one million AEDs scattered around the United States, the answer, all too often when people suffer sudden cardiac arrests, is no.
In a Perspective piece published online this week in the journal Circulation: Cardiovascular Quality Outcomes, two researchers from the Perelman School of Medicine at the University of Pennsylvania outline the tremendous potential associated with greater utilization of AEDs in public places and a method to find ...
LOS ALAMOS, New Mexico, February 24, 2012—A multinational team of scientists has developed a process for creating glass-based, inorganic light-emitting diodes (LEDs) that produce light in the ultraviolet range. The work, reported this week in the online Nature Communications, is a step toward biomedical devices with active components made from nanostructured systems.
LEDs based on solution-processed inorganic nanocrystals have promise for use in environmental and biomedical diagnostics, because they are cheap to produce, robust, and chemically stable. But ...
