Chapter 1: Intro to climate change Flashcards
Global warming is
the gradual rise in the earth’s temperature caused by high levels of CO2 and other greenhouse gases (GHGs) in the atmosphere
Global warming occurs when
the radiation balance of the planet is disrupted
As global climate is determined by the …………………………. global warming results in ……………………
radiation balance of the planet
corresponding change in climate
There are three fundamental ways the Earth’s radiation balance can change, thereby causing a climate change:
- changing the incoming solar radiation (e.g., by changes in the Earth’s orbit or in the Sun itself),
- changing the fraction of solar radiation that is reflected (this fraction is called the albedo – it can be changed, for example, by changes in cloud cover, small particles called aerosols or land cover), and
- altering the longwave energy radiated back to space (e.g., by changes in greenhouse gas concentrations).
local climate also depends on
how heat is distributed by winds and ocean currents
A greenhouse gas (GHG) is
any gas in the atmosphere that absorbs and emits radiation in the thermal infrared range. These are the fundamental cause of the greenhouse effect, which results in global warming.
explain how the green house effect warms the earth
- short wave energy heats the surface
- long wave energy radiate into atmosphere then into space
- GHG absorb some of the energy and trap it in the LOWER atmosphere and emit heat energy in all direction
- less heat radiate into space
- earth is warmer
Thus, the greenhouse effect is a natural occurrence that maintains Earth’s average temperature at approximately ………., warmer …………… than it would be otherwise ………………..
288 K (15 c)
33 K
255 K (-18 c)
Many greenhouse gases occur
- NATURALLY: Carbon dioxide, methane, water vapor, and nitrous oxide are naturally present in Earth’s atmosphere.
- HUMAN MADE: such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)
Each molecule of greenhouse gas becomes energized by
the long wave radiation.
- The energized molecules of gas then emit heat energy in all directions.
- By emitting heat energy toward Earth, greenhouse gases increase Earth’s temperature.
……………….. resulted in a sharp rise in GHG emissions
Increasing population and dependence on fossil fuels for energy
For example, CO2 concentrations were fairly stable at …………….. before the Industrial Revolution (1950). Now, they hover around ……………….. and more
280 ppm
370 ppm
Climate sensitivity is the term used to express
the relationship between the human-caused emissions like CO2 and other GHGs that add to the Earth’s greenhouse effect and the temperature changes that will result from these emissions.
- how much the average global surface temperature will increase if there is a doubling of greenhouse gases in the air.
- direct measure of how the earths climate will respond to doubling
That value, according to the most recent IPCC report, is ………….. degrees Celsius, with a range of uncertainty from……………
3
2 to 4.5 degrees.
This sensitivity depends primarily on
all the different feedback effects, both positive and negative, that either amplify or diminish the greenhouse effect.
There are three primary feedback effects —
- clouds,
- sea ice and
- water vapor;
these, combined with other feedback effects, produce the greatest uncertainties in predicting the planet’s future climate.
With no feedback effects at all, the change would be
1 degree celcius
Clouds are a good example. Clouds can have ……………. feedback. depending on ………..
positive or negative
- their altitude and
- the size of their water droplets
Clouds are a good example. Clouds can have either a positive or negative feedback effect, depending on their altitude and the size of their water droplets. Overall, most scientists expect this net effect to be
positive, but there are large uncertainties
It is important to note that climate sensitivity is figured on the basis of an overall
doubling, compared to pre-industrial levels, of CO2 and other GHGs
It is important to note that climate sensitivity is figured on the basis of an overall doubling, compared to pre-industrial levels, of CO2 and other GHGs.
• But, the actual increase might be greater in the long run because
greenhouse gas levels in the atmosphere could more than double without strong policies to control emissions.
But in the short run, the actual warming could be less than suggested by the climate sensitivity, since due to
the thermal inertia of the ocean, it may take some time after a doubling of the concentration is reached before the climate reaches a new equilibrium
anomalies are analysed to
understand the global temperature changes, rather than the actual temperature
A temperature anomaly is the
between the temperature that is actually occurring and a long term average temperature (reference temperature).
- In other words, the long-term average temperature is one that would be expected; the anomaly is the difference between what you would expect and what is happening.
