Climate change (Class of 2019): Introduction
- [x] What is your climate like? (Kids' Crossing) by University Corporation for Atmospheric Research, USA
- What is climate? ... Three layers of the concept of climate.
- 1. Natural environment surrounding human settlements,
with emphasis on conditions of the atmosphere near the ground -- e.g. hot/cold, wet/dry .
(風土 ja:hû-do, zh:feng-tu, literally "wind and soil".)
- 2. State of near-ground atmosphere, which can be expressed by multi-decadal (typically 30-year)
statistics of physical (meteorological) variables. e.g. air temperature, precipitation (rainfall and snowfall).
Note: not only the average but variabilities and extremes are relevant.
- 3. State of the "climate system" (to be discussed shortly).
- Weather and climate (meaning No. 2): a matter of time scales
- weather (ja: 天気 tenki; 気象 kisyô) ... hours to days.
- (short-term climate?) (ja: 天候 tenkô) ... weeks to years (regular seasonal variation sorted out)
- climate (ja: 気候 kikô) ... decades, centuries or longer.
- Note: Inter-annual variability (of tenkô) exist within any one state of climate (kikô).
In English, "climate prediction" usually means prediction of inter-annual variation.
In Japanese, this activity is usually called "季節 予報 kisetu yohô literally "seasonal prediction (of something)".
- [x] Global Average Surface Temperature Anomalies by Japan Meteorological Agency (気象庁 Kisyôtyô)
- Climate change (ja: 気候 変化 kikô henka; 気候 変動 kikô hendô)
- The state of climate can change, in various time scales.
- Climate may change because of external forcing, or it may change spontaneously.
- To understand changes of climate (even if meaning No. 2), we need the concept of "climate system".
- Overview of the "climate system"
- Components: atmosphere, ocean, ice and snow, "land surface"
- Stock and flow of mass (mainly of H2O) and of energy
- Global environmental issues (地球 環境 問題 tikyû kankyô mondai) as interaction between natural environment and human society
- Human society is embedded in natural environment.
But it is rather an autonomous system.
So we think of interactions between natural environment and human society.
- Natural environment poses constraints to human society (though it does not completely determine it.)
- When human population was small, human society did not modify natural environment so much.
The interaction is almost in one-direction.
- As human population and per-capita activity grow,
humans modify natural environment, so mofify the constraints to human society.
When the modification is unfavorable to humans, it is recognized as environmental problems.
- Agriculture and deforestation caused regional environmental problems.
Migration may be solution.
- Industrialization (popular use of fossil fuel) caused global environmental problems.
We cannot escape from the global earth.
- Figures: see [Earth system(s) and environmental problem(s)] (where "natural environment" is divided into "atmosphere + hydrosphere" and "ecosystem")
- "Climate change" as a natural process
- Internal (spontaneous) change
- Change due to natural forcing
- Change due to anthropogenic (=caused by humans) forcing
- Can climate be changed? ... The following 3 questions are very different from each other.
- This issue was not mentioned in the lecture of 2019-04-11. It will be discussed in some other day.
- 1. Can climate change (in a time scale of a century, e.g. a few generations of human beings)?
- 2. Can human activities change climate significantly?
- 3. Can humans change climate as they like?
- Anthropogenic climate change as a global environmental issue
2019-Apr-09; Updated: 2019-Apr-11, 2019-Apr-18