Cooling: Solar Radiation Management
(Geo-Engineering)
The biggest form of geo-engineering is adding vast amounts of CO2 to the air.
That causes huge damages, most of them delayed,
The biggest form of geo-engineering is adding vast amounts of CO2 to the air.
That causes huge damages, most of them delayed,
The graph of energy intensity (density) radiated to space by Earth, on the vertical axis, correponds to frequency on the bottom and wavelength on the top. Less is radiated to space in the absorption bands of the principal greenhouse gases (GHGs). The principal atmospheric infrared window thru GHGs is 10 to 12 µm. 320 K, the top "curve", = 47°C = 117°F. 22°C MODTRAN Model with Tropical setting = 295 K = 72°F.
The figures below show the increase in absrobed solar radiation over time and space. The left graphs shows that, over 20 years, Earth has absorbed more solar radiation - it has been getting darker (less reflective) - over the 3 major ocean basins. Especially over the North Pacififc and North Atlantic.
Changes over land are not shown.
Dr. Fry's summary of leading SRM methods.
An HPAC member's take on relative effectiveness of 9 methods to cool the planet (atmosphere mostly). Marine Cloud Brightening is rated top, followed by atmospheric methane oxidation.
Below, as above, SAI = Stratospheric Aerosol Injection (what major volcanic eruptions do) and MCB = Marine Cloud Brightening. CH4 is Methane, the leading Well Mixed Greenhouse Gas besides CO2.
Earth is getting darker, which makes it absorb more heat, and thus warm up. Warming is not just from greenhouse gases. However, the changing albedo was initiated by adding greenhouse gases, which were the trigger.
At right, observe that the dark forest (mesic savanna) reflects less sunlight than the semi-arid savanna or the aird savanna. The more arid conditions will have a net cooling effect, other things equal.
2 methods reviewed: stratospheric aerosol injection and marine cloud brightening
The figure shows 4 types of SRM and 5 types of CO2 removal. Some methods are not shown, especially for CO2 removal, notably organic farming for soils. Also CH4 removal, notably by iron salt aerosols.
SRM shown includes mirrors, aerosols, reflective crops, and cloud seeding.
CO2 removal shown includes foresting, artificial trees, biochar, ocean iron fertilization, and carbonate addition. Accelerated rock weathering, a major method, is not shown, nor is use of ocean biology.
Add to the diagram storing carbon in soils, via (1) rapid (~1 week / small pasture) rotation grazing, (2) no-till farming, especially organic farming, and (3) biochar.
LIke foresting, these requires large land areas, but they (especially grazing) work much better in dry areas, which will grow some grass but few or no trees. Like foresting, these are already being used, at negligible cost. Moreover, soils generally store more carbon per acre than standing biomass (e.g., forests), especially toward the poles. (But near the equator, standing biomass stores much more than the soil there, except in peatlands.)
Section Map: Reversing Climate Change