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.
A positive anomaly means that
the temperature was warmer than normal
negative anomaly indicates
that the temperature was cooler than normal
The main reason for using temperature anomalies rather than analysing the temperature directly, is that:
- The actual temperature can vary sharply over short distances, but its anomalies are constant over much longer distances.
- This makes the calculation of anomalies more accurate by requiring a less dense measurement network.
Using anomalies, the departure from an “average,” allows
more accurate descriptions over larger areas than actual temperatures for easier analysis
Arctic sea ice extent 1979-2005
- Sea ice extent is a measure of the surface area of the ocean covered by sea ice.
- The sea ice extent in the Arctic, measured in September of each year (when sea ice extent reaches its annual minimum), has decreased by about 36% since 1979
explain how sea ice extent cause warming
- increase in air and ocean temp decrese extent (melting of sea ice)
- reduce area of white surface
- less raduation is reflected
- become dark ocean surface (absorb radiation)
- snow covered absorb 20%
- ice free area absorb 90%
- warm ocean
- melt ice from below and release heat to the atmosphere before ocean refreezes in winter
- less sea ice
- warmer climate
effects of warming due to the decrease of sea ice extent
- wind patterns in NH shift (as Arctic atmosphere warms)
- risk of erosion along coastlines
- changes the presence of marine species in some areas
- effecting commercial fish stocks (and economics of local towns)
Impacts of Global Warming
- Sea level rising and increased coastal flooding
- An Increase in Extreme Weather Events
- Heavier precipitation and flooding
- More severe droughts in some areas
- Melting Ice
- Impacts on Agriculture
- Plant and animal range migration
Sea level rising and increased coastal flooding
- global sea level increased 8 inches since 1880
- rising faster in some areas
- global warming is
- accelerate the rate of rise
- increasing flood risk to low laying land and coastal properties (development encouraged by insurance)
An Increase in Extreme Weather Events
- global warming causes increase in
- heat waves
- coastal flooding
- extreme precipitation events
- severe drought
- more powerful hurricanes
Heavier precipitation and flooding
As temperatures increase, more rain falls during the heaviest downpours, increasing the risk of flooding events.
More severe droughts in some areas
Climate change affects a variety of factors associated with drought and is likely to increase drought risk in certain regions
Melting Ice
- temperatures rising in poles
- especifically arctic
- glaciers are melting faster than snow and ice is forming
rate of melting is expected to accelerate and cause more sea level rise
Impacts on Agriculture
- global warming
- rising temperature
- heat waves
- heavy precipitation
- severe drought
- rising temperature
these effect crop production and the food supply
Plant and animal range migration
- A changing climate affects the range of plants and animals, changing their behavior and causing disruptions up and down the food chain.
- The range of some warm-weather species will expand, while those that depend on cooler environments will face shrinking habitats and potential extinction
