Write down 5 key words to
summarise these pictures.
Global warming intro…
Learning outcomes
All of you should be able to:
• Identify the different greenhouse gases (GHGs)
Most of you should be able to:
• Describe the role of greenhouse gases (GHGs) in
maintaining mean global temperature.
• Describe how human activities add to
greenhouse gases (GHGs)
Greenhouse gases
Which of these gases are greenhouse gases?
• water vapour (H2O)
• carbon dioxide (CO2)
• methane (CH4)
• nitrous oxides (N2O)
• ozone (O3)
• CFC’s
(Greenhouse gases) trap the radiation from the
sun that is reflected back from the Earth.
Greenhouse effect
Source: Solcomhouse.com
About 45% of the incoming
light is reflected before it
reaches the surface.
51% is absorbed by Earth’s
surface and 4% is reflected.
The Greenhouse Effect
• Essential for life to exist on the planet.
• Without it the planet would be 33°C cooler.
HOWEVER
• As humans increase emissions of some GHGs the
greenhouse effect is exaggerated or enhanced.
• Most climate scientists believe that this is causing
global warming and climate change.
Recall…
• Describe the greenhouse effect?
• Explain the process?
• Give 3 examples of a greenhouse gas.
The concentration of carbon dioxide in the atmosphere from 1958-2004
http://gu.com/p/3fyeq
carbon dioxide
temperature
NASA’s Goddard Institute for Space Studies. (2006) “Global temperature change”. Proc. Natl.
Acad. Sci. 103: 14288-14293. Following the common practice of the IPCC, the zero on this figure
is the mean temperature from 1961-1990.
As you can see...
global temperatures are rising!
Changes in carbon dioxide concentrations during the Phanerozoic era. Three estimates are based on geochemical modelling:
GEOCARB III (Berner and Kothavala 2001), COPSE (Bergmann et al. 2004) and Rothman (2001). These are compared to the
carbon dioxide measurement database of Royer et al. (2004) and a 30 Ma filtered average of those data. Error envelopes are
shown when they were available. The right hand scale shows the ratio of these measurements to the estimated average for the
last several million years (the Quaternary). Courtesy: Robert A. Rohde, Global Warming Art
The observed sea ice in 1979 and 2003
Jacabamba Glacier, Peru, in 1980 (left) and 2002 (right)
Explanations for these trends?
• The onset of global industrialisation and
pollution derived from fossil fuels
• Deforestation (particularly of rainforest)
• Volcanic activity
Assume a link between
carbon dioxide emissions
• Sunspot activity
and temperature
increase
Suggest possible natural
phenomena that may
have increased
temperatures.
Think, pair, share
What do you think are the main human
activities releasing GHGs?
Hint: use your knowledge of what the main
GHGs are.
The direct warming influence
of all long-lived greenhouse
gases in the atmosphere today
attributable to human
activities.
CO2’s warming influence of 1.7
watts/m2 is equivalent to the
heat from nearly 9 trillion 100watt incandescent light bulbs
placed across Earth’s surface.
The combined influence of the
non-CO2 greenhouse gases is
equivalent to the heat from
about 5 trillion bulbs. The
category “other” includes a
few very long-lived chemicals
that can exert a climate
influence for millennia.
(Credit: NOAA - National Oceanic and Atmospheric Administration)
Checking outcomes
All of you should be able to:
• Identify the different greenhouse gases (GHGs)
Most of you should be able to:
• Describe the role of greenhouse gases (GHGs) in
maintaining mean global temperature.
• Describe how human activities add to
greenhouse gases (GHGs)
Confirm you know them…
• What are 4 greenhouse gases?
• Describe how GHGs maintain the mean global
temperature?
• List at least 4 human activities that add to GHGs.
• Describe how each one adds to GHGs.