# 6 Session 5 summary

Some forcings could, in principle, be altered to reduce energy in to Earth’s energy balance by reflecting sunlight (solar radiation management, SRM) or to increase energy out by reducing the greenhouse effect (carbon dioxide removal, CDR).

A solar shield in space could, in principle, reflect sunlight away from the Earth, and increasing the albedo of cities is a well-understood method for reflecting more sunlight locally. Stratospheric sulfate aerosol injection and marine cloud brightening are further potential ways to increase the reflection of sunlight, either directly by the particles in the atmosphere or by the brighter clouds they can produce.

Photosynthesis can remove carbon dioxide from the atmosphere via enhanced plant growth (terrestrial or marine) combined with long-term storage of carbon in geological, ocean or soil reservoirs. Technological means of capturing CO2 from the air also exist, such as artificial trees.

Geoengineering may provide co-benefits additional to those of changing global climate.

In the next session, you will study the design, experiments and implementation of these methods of engineering the climate.

Get started on Session 6.

OpenLearn - Could we control our climate?
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