Wigley calculates the impact of injecting sulfate particles, or aerosols, every one to four years into the stratosphere in amounts equal to those lofted by the volcanic eruption of Mt. Pintabuto in 1991. If found to be environmentally and technologically viable, such injections could provide a "grace period" of up to 20 years before major cutbacks in greenhouse gas emissions would be required, he concludes.
"A combined approach to climate stabilization has a number of advantages over either employed separately," says Wigley. His study was supported by the National Science Foundation, NCAR's primary sponsor.
The Science paper does not endorse any particular approach to reducing climate change, nor is it intended to address the many technical and political challenges involved in potential geoengineering efforts. Instead, it analyzes whether the much-discussed idea of injecting sulfates into the stratosphere could, in fact, slow down global warming and therefore provide more time for society to reduce the emissions of carbon dioxide.
If climate change were addressed only through mitigation (emissions reduction), then massive cuts in emissions would be needed in order to keep temperatures from rising more than 3.6 degrees Fahrenheit (2.0 degrees Celsius) over present levels. This amount of warming has often been cited as a benchmark of dangerous climate change.
Given the difficulties of making such massive cuts, scientists recently have begun to reexamine a variety of schemes proposed over the last few decades to reduce the impact of climate change through global-scale technological fixes. These approaches are often referred to as geoengineering. One strategy first proposed in the 1970s is to inject large amounts of sun-blocking sulfate particles into the stratosphere via aircraft or other means. The idea would be to cool the climate for a year or more with each injection, much as the largest volcanic eruptions do.
"Geoengineering could provide additional time to address the economic and technological challenges faced by a mitigation-only approach," says Wigley.
-----A model experiment with two scenarios-----
Using a computer model to track sunlight and other energy flowing into and out of the Earth system, Wigley examined two scenarios that project the impact of emissions on climate from now to the year 2400. In one scenario, total emissions would have to start dropping immediately, and would have to be cut by around 50 percent in the next 50 years, in order to keep global climate from warming by more than the 2 degrees C benchmark. An alternative scenario, the "overshoot" approach, allows a period of increasing total emissions, extending to the 2030s, before stringent cutbacks begin.
To see how geoengineering might change this picture, Wigley took the overshoot scenario and added three frequencies of Pinatubo-scale injections of sulfates into the stratosphere. The frequencies were equivalent to an eruption every year, every two years, and every four years. In all three cases, global temperature stayed approximately constant for the next 40 to 50 years. After 2050, the cumulative effect of greenhouse gases produced a slow temperature rise, though it was muted by the injections.
Injections on a scale equal to Pinatubo were examined because that volcanic eruption did not seriously disrupt the climate system beyond a short-term cooling, says Wigley.
Geoengineering is not a panacea, Wigley notes. For example, carbon dioxide from fossil fuel burning has led to an increased acidification of Earth's oceans. Even if geoengineering could help limit global warming, the oceans would continue to acidify as greenhouse-gas emissions climb, threatening certain marine ecosystems.
Mitigation alone can potentially solve both the warming and ocean acidification problems, but it has its own set of difficulties, says Wigley. The rapid emissions reductions required to keep below the 2 degree C warming threshold would be costly, perhaps unacceptably so, and would pose severe technological challenges.
"A relatively modest geoengineering investment could reduce the economic and technological burden on mitigation by deferring the need for immediate or near-future cuts in carbon dioxide emissions," Wigley says.
David Hosansky | EurekAlert!
Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University
Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy