Climate change (Class of 2019)

Carbon dioxide and (steady state) climate change (3)

"When global warming was discovered?"

Development from consensus among experts to a politically relevant issue

Today's subject: aspects within natural science. (Discussion about social and political factors ... postponed).

Explanation of global warming as slow transition between quasi-steady states

(Manabe, lecture in 1983, a Japanese publication 1985, redrawn by Masuda 2014)

Included in [Materials of 2019-May-23], but not explained yet.

Other factors than CO2?

How fast will our climate change?

Need to discuss time-dependent (transient) states rather than steady states

Two kinds of stock (reservoir)

Energy balance of the climate system

C dT/dt = F

Problem: what comprises C?

Major reservoirs of energy

Carbon cycle, esp. Mass balance of carbon dioxide in the atmosphere

Defelopment in the 1980s w.r.t. energy cycle and temprature

"transient response experiment" with 3-dimensional coupled ocean-atmosphere model by Spelman and Manabe (1984)

Idealized condition

See [Delay due to oceanic heat capacity]

Main result: Upper ocean warms together with the atmosphere. The time scale is decades (tens of years).


More realistic experiments followed.

Carbon cycle

Empirical fact (as of 1970s-1980s)

Difficulty in explaining "sinks" (=negative sources)

Tentative assumption (common as of 1980s)

later finding (1980s-2000s)

Both are not gurranteed to continue at similar fraction in the future.

Impact on climate change on agriculture (and food), forestry, and natural ecosystems

Scientific studies were promoted in 1980s.

"Something bad may happen. International policy may be needed." -> momentum to establish IPCC etc.

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