The amount of cumulative CO2 emissions that will result in a 2° C temperature increase is relatively well known and quantified: one trillion tonnes of CO2, half of which has already been emitted. The question that remains is “what proportion can aviation have of the half a trillion tonnes of CO2 that can be emitted, before surface temperatures increase beyond 2° C?
Aviation climate impacts are due to both CO2 and non-CO2 emissions. The non-CO2 emissions include water vapor (H2O), nitrogen oxides (NOx), sulfur oxides(SOx), hydrocarbons (HC), and black carbon (or soot) particles.
Aviation CO2, H2O and soot emissions contribute directly to climate change with positive radiative forcing (net warming). Whereas, emissions of NOx, SOx, H2O and black carbon aerosols contribute indirectly to climate change.
In general, there is a better understanding of impacts of GHG emissions that have a direct impact on the climate than emissions that have indirect impacts. For example, while the scientific understanding and modelling of NOx effects have substantially improved over the last few years, there is still uncertainty regarding the exact extent to which NOx emissions from air travel affect climate change through their impact on ozone formation and methane destruction. Similarly, H2O vapor emissions can trigger formation of contrails in sufficiently cold air masses which may persist for hours and can potentially increase cirrus cloudiness. Direct emissions of black carbon and in situ formed aerosols can also serve as cloud condensation nuclei which, along with background aerosols, facilitate the forma- tion of contrails and cirrus clouds. Contrails and induced cirrus clouds reflect solar short-wave radiation and trap outgoing long-wave radiation resulting in the net positive contribution to climate change.
I will often replace the term “Solar Radiation Management” with the word “geoengineering”. And I will often loosely refer to the “changes in the amount of energy entering or leaving some part of the planet because of some climate factor” as a “forcing”. So there is a forcing associated with increasing greenhouse gases, and there is another forcing associated with Solar Radiation Management. The idea is to try to match the forcings so that they kind of cancel.
You might also be interested to know that scientists have occasionally considered using other kinds of particles to do geoengineering. But you asked me to focus on sulfate aerosols so I will not discuss other particles further.
clouds as a whole tend to cool the planet more than they warm it.
If one introduces extra aerosol into a region where a cloud is going to form, then when the cloud forms, there will be more cloud drops in it than there would otherwise have been.
Here are four take-home messages of my testimony:
1) Some biological and land-use strategies for geoengineering are already feasible, including restoring or planting forests, avoiding deforestation, and using croplands to reflect sunlight and store carbon in soils.
2) Biological and land-based geoengineering alters carbon uptake, sunlight absorption, and other biophysical factors that affect climate together.
3) Geoengineering for carbon or climate will alter the abundance of water, biodiversity, and other things we value.
4) A research agenda for geoengineering is urgently needed that crosses scientific disciplines and coordinates research across federal departments and agencies.
Together, air capture and mineral sequestration provide a comprehensive solution to combat climate change. Capturing carbon dioxide from the air and storing it safely and permanently as solid mineral carbonate provides a way to maintain access to plentiful and affordable energy, while stabilizing the carbon dioxide concentration in the atmosphere. Abandoning fossil fuels would seriously affect energy security. On the other hand, the continued emission of carbon dioxide would have harmful consequences for climate, oceans, and ecosystems. Air capture can extract unwanted carbon from the atmosphere, and mineral sequestration can provide a virtually unlimited and safe reservoir for the permanent storage of excess carbon.
Two kinds of geoengineering
Geoengineering describes two distinct concepts. Carbon Dioxide Removal (CDR) describes a set of tools for removing carbon dioxide from the atmosphere, while Solar Radiation Management (SRM) would reduce the Earth‘s absorption of solar energy, cooling the planet by, for example, adding sulfur aerosols to the upper atmosphere or adding sea salt aerosols to increase the lifetime and reflectivity of low-altitude clouds.
Solar-radiation management may be the only response that can fend off unlikely but rapid and high-consequence climate impacts.
Originally posted by thruthseek3r
reply to post by pianopraze
Great video, interesting stuff out there. I started recently worrying about chemtrails because here In Canada I start to hear more and more planes passing by during these days. Maybe it has nothing to do with it but I noticed the trails in the sky and it's not a recent phenomenon. I watched the video only 5 min and plan to watch it completely someday.
Star for this post.
What is claimed is:
1. A method of reducing atmospheric warming due to the greenhouse effect resulting from a layer of gases in the atmosphere which absorb strongly near infrared wavelength radiation, comprising the step of dispersing tiny particles of a material within the gases' layer, the particle material characterized by wavelength-dependent emissivity or reflectivity, in that said material has high emissivities with respect to radiation in the visible and far infrared wavelength spectra, and low emissivity in the near infrared wavelength spectrum, whereby said tiny particles provide a means for converting infrared heat energy into far infrared radiation which is radiated into space.
2. The method of claim wherein said material comprises one or more of the oxides of metals.
3. The method of claim 1 wherein said material comprises aluminum oxide.
4. The method of claim 1 wherein said material comprises thorium oxide.
5. The method of claim 1 wherein said particles are dispersed by seeding the stratosphere with a quantity of said particles at altitudes in the range of seven to thirteen kilometers above the earth's surface.
6. The method of claim 1 wherein the size of said particles is in the range of ten to one hundred microns.
The present invention is for a powder generator requiring no heat source to emit a "contrail"
Purpose: show a potential use for GMI with stratospheric aerosols coupled to chemistry climate model
Funding for this project provided to AER from NASA/ACMA
The radiative forcing due to a distinct pattern of persistent contrails that form into contrail-induced cirrus near and over the UK is investigated in detail for a single case study during March 2009. The development of the contrail-induced cirrus is tracked using a number of high-resolution polar orbiting and lower-resolution geostationary satellite instruments and is found to persist for a period of around 18 h, and at its peak, it covers over 50,000 k
•International governance of potential SRM activities needs to be established soon, to deter unilateral experimentation w/ particle injection.
•The Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD) Treaty, the Convention on Biological Diversity, the United Nations Framework Convention on Climate Change, the Montreal Protocol on Substances that Deplete the Ozone Layer, & the Long-Range TransboundaryAir Pollution Convention & others may serve as models for a governance framework & a binding int'l treaty that prohibits unilateral & potentially dangerous application of SRM.
•To detect & deter unsanctioned SRM development activities will require monitoring systems that can reliably detect early test phases involving relatively small amounts of particles.
•Our preliminary finding is that reliable detection of small clandestine tests from space will be very challenging.
•This preliminary finding has important implications in future treaty negotiations, which may need to consider alternative methods of monitoring such activities.
•As w/ nuclear test monitoring, detecting clandestine particle-injection experiments & development activities will require a combination of techniques & involving extensive ground, space & other means.
•However, given the strong need for improved understanding of the role of aerosols in the stratosphere, as well as for applications such as the monitoring of volcano dust for airline safety, the impetus may exist for
the development of a multifunction system of space-based sensors.