Chapter 7 Flashcards
intro
- Climate is naturally variable
- Over the past 100 years or so, the world’s climate has changed noticeably
- By early in the twenty-first century, climate change had become part of the vocabulary of the North American public
- Much complexity and uncertainty is associated with climate change
weather
- Refers to short-term (hourly or daily) fluctuation of atmospheric conditions (air temperature, humidity, type and amount cloudiness, type and amount precipitation, atmospheric pressure, and wind speed and direction) (elements of weather).
e. g. cloudy, raining, 10C
climate
- In contrast, climate refers to long-term average of atmospheric conditions of a specific region or entire planet, such as:
- Temperature (e.g. Winnipeg: monthly mean temperature for July is 22ºC, January=-18ºC, Vancouver: July 16ºC and Jan. 3ºC.
- The global average temperature of the Earth is: 15º C = 59º F.
climate change vs global warming
-is a long-term alteration in the climate of a particular location, region or for the entire planet (temperature, clouds, precipitation, frequency of weather events
(warmer or colder, wetter or drier)
-In contrast, global warming addresses changes only in average surface temperatures
nature of climate change
- Natural events, such as volcanoes and El Niño, are known to have an influence on climate
- Volcanoes, eject large quantities of dust and sulphur particles into the atmosphere, which reduce the amount of solar radiation reaching the surface of the Earth
- El Niño represents a marked warming of the waters in the eastern and central portions of the tropical Pacific that triggers weather changes and events in two-thirds of the world
what happens after volcanic eruption
Following a volcanic eruption, large amounts of SO2, HCl and ash spew into the Earth’s stratosphere
The following statements are supported by solid scientific evidence
- The world has been warming
- Greenhouse gas emissions have been rising for several decades( CO2, CH4, N2O and tropospheric O3)
- Glaciers have lost more mass than they have gained
- Reduced snow cover has been documents, as well as earlier spring melting of ice on rivers and lakes
- Total sea ice in Canada has been declining each decade
- Measurements show that permafrost is warming in many regions. Over one-half of Canada is underlain by permafrost
scientific evidence related to climate change
- The increase in the average temperature of the northern hemisphere during the 20th century was the largest of any century in the past 1,000 years
- The average rate of sea-level rise rose from 0.1 to 0.2 mm/year during the past 3,000 years to 1 – 2 mm/ year in the 20th century, a tenfold increase, and
- traditional environmental knowledge all indicate that climate change is occurring
who is a major contributor to rising level of CO2
The forest industry is a major contributor to the rising levels of carbon dioxide in the atmosphere, not only through deforestation, but also through emissions from processing plants
Maldives rising sea levels
Some countries, such as the Maldives in the Indian Ocean, are so low-lying that they could be mostly flooded as early as early as 2050 if global sea levels rise as predicted
primary cause for climate change
Fossil fuel combustion is the primary cause for climate change
greenhouse effect
- Earth’s surface radiate infrared energy back toward space
- Greenhouse gases (including water vapor) absorb the outgoing infrared energy and trap heat close to the Earth’s surface.
- This warms up the troposphere and the Earth’s surface
- Humans have increased concentrations of greenhouse gases in the troposphere
sources of greenhouse gases
- Carbon dioxide
- methane
- nitrous oxide
carbon dioxide
fossil-fuel burning
–Atmospheric levels increasing steadily
–Most important cause of warming
methane
ruminants, rice paddies
–Absorbs more infrared than CO2
nitrous oxide
–burning organic material
–Using inorganic fertilizers
global warming effects
-More extreme weather; droughts, floods, heat waves and hurricanes.
-These extremes have increased significantly in the last decade.
-Sea level has risen 6 to 8 inches in last century.
-If we do nothing, Greenland’s ice will melt and raise sea levels 20 ft.
-South Pacific island nation of Tuvalu already abandoned due to climate change
Growing seasons- lengthening in Northern hemisphere.
-Some animals are breeding earlier or extending their range. Others are disappearing.
-Droughts are more frequent and widespread
-Storms more severe.
-Infectious diseases will increase. Why?
–Insects that spread them are able to move to places where they could not live before.
–West Nile, malaria, and dengue fever have appeared in North America.
modelling climate change
- The uncertainty associated with global climate is encouraging scientists to explore many different ways of assessing past and future climates
- One approach is climate modelling
- Climate models are computer codes, which are used to test the validity of a proposed hypotheses and to predict future climate change