Transcript Global warming leads to…

CHAPTER 16:
GLOBAL
WARMING
Global Change
• Changes in environmental processes affecting the whole Earth
• Temperature changes in the last decade.
Which part of Canada has seen the greatest temperature changes?
Why study global change?
• Atmospheric CO2
concentration exceeded 400
ppm in May of 2013 – higher
than at any other time in past
15 million years.
• 2010 is the hottest year on
record, and 2007 is the second
hottest
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12 out of the 13 hottest years
ever recorded have taken place
since 2001
We are not even close to seeing
the full effects of 400 ppm CO2.
15 million years ago, when the
climate was in equilibrium with
similarly high CO2 levels, sea
level was 23 to 36 m higher than
it is now, and the global
temperature was 2.8°C to 5.5°C
warmer.
Definitions
• Global warming
– increase in the average temperature of Earth’s surface
– (including the oceans)
• Climate
– long-term (~30 years) average weather pattern in a particular region resulting
from interactions among land, ocean, atmosphere, ice, and the biosphere
• Global climate change
– any large-scale change in climate over time, whether natural or as a result of
human activity
Earth's 7.2 billion people are using natural
resources 23% faster than the natural renewal rate!
Is our use of natural resources sustainable? Is it justifiable?
Heat Circulation in the atmosphere and
oceans maintains Earth’s climate
• Climate Change is caused by
changes in the way this heat
moves and accumulates in
the atmosphere...
Thermohaline Circulation
• ... and in the Oceans.
Circulation patterns in the troposphere
The greenhouse effect is at the heart of
Earth’s climate system
• The greenhouse gases of our atmosphere have the ability to absorb and store
heat radiated from the surface of the Earth
• The greenhouse effect maintains Earth’s average temperature at ~14°C
(conditions conducive to life)
• Without the greenhouse effect Earth’s average temperature would be -18°C
Earth's heat budget
Greenhouse Gases
• Absorb long-wave radiation (IR energy radiated from the surfaces of the earth
that have been warmed by the sun)
• Represent ~1% of the atmosphere
Steven Earle
Water vapor (H2O)
Carbon Dioxide (CO2)
Ozone (O3)
(0.04%)
Methane (CH4)
fluorocarbons
Nitrous Oxide (N2O)
The composition of the
atmosphere (excluding
H2O). The greenhouse
gases ozone, fluorocarbons
and nitrous oxide are
included in “others”. Their
proportions are small, but
their effect is real.
The Rise in CO2
• Today's carbon dioxide level of 400 ppm is well above natural levels for the
past 400,000 years, as shown here, and in fact for the past 15 million years.
What is the
explanation for the
cyclical patterns of
past temperatures
and GHG levels?
Important greenhouse gas concentrations in
Earth's atmosphere from 1978 to 2010
The global carbon cycle describes how
carbon moves through natural systems
What is the largest reservoir of carbon
according to this diagram?
Carbon is found in many forms ...
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Rocks in the lithosphere
Carbon dioxide dissolved in water
Organic matter in the biosphere and the lithosphere
Gases in the atmosphere
but most carbon is stored
in rocks
A limestone mountain in the southern Rockies
near to the BC-Alberta border
Climate modeling
• Climate modeling improves our understanding of global change
Actual T changes (
) are most closely
represented by models that consider
anthropogenic forcings
Parallels
• Atmospheric CO2 levels kept pace with the warming climate of the last deglaciation and the steady climate of the Holocene interglacial, but the change
in CO2 levels over the past century has no parallel in the geological record.
400 ppm in 2013
What is the cause of the huge spike in CO2 levels over the past century?
The Increase in CO2 Levels
• The human contributions to the dramatic increase in CO2 levels are primarily
due to:
• The burning of fossil fuels
The Increase in CO2 Levels
• Deforestation and the burning of organic biomass
The Increase in CO2 Levels
• and the production of cement.
Limestone quarry and cement plant near to Exshaw Alberta in the Canadian Rockies
Steven Earle
The Increase in CO2 Levels
• In the last 200 years atmospheric carbon dioxide levels have risen by almost
50%.
• In the last 70 years natural resource use has increased ten-fold and the human
population has tripled.
• ~83% of global human greenhouse gas emissions are produced by 25
countries and ~42% are produced by just 2 countries.
Which two countries are responsible for 42% of global GHG emissions?
Population growth is a major part of the
problem
Population growth
(global)
Percentage of growth
(annual)
These are global
figures. There are
regional variations
related to
automobile use and
methods of
electricity
generation.
How might the
numbers for your
region be different
than these?
Earth’s average temperature
has risen by over 0.8°C in the past 100 years
Past Temperature
• Earth’s average temperature dropped very slowly over the 1200 years from
700 to 1900 AD, but has increased quickly since then.
Annual Sea Ice Minimum
• The Arctic has warmed by ~2.7°C in the last 30 years, considerably more than other
parts of the Earth. One reason for that is the loss of approximately half of the
permanent Arctic sea ice over that time.
Why might sea-ice loss have such a dramatic effect on the climate of the
Arctic region?
Sea level rise accelerated over the period
since 1996
Global warming leads to…
• ocean warming and acidification
What is the
problem with
ocean
acidification?
Global warming leads to…
• loss of glacial ice
Global warming leads to…
• Sea level rise
Steven Earle
Global warming leads to…
• Changes in extreme weather
Global warming leads to…
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Degradation and shrinkage of wildlife habitats
Changes in the distribution of food sources
Disruption of the timing of migration patterns
Increased range of pest insects (e.g., mountain pine beetle)
Desertification
Increase in the incidence of slope failures because of heavy precipitation
Several international efforts focused on
understanding and managing climate change
• Intergovernmental Panel on Climate Change (IPCC)
• The Kyoto Protocol
– Carbon quotas
– Emissions trading
• But many individuals, corporations and governments show no interest in
taking the decisive action that will lead to the needed changes.
What type of individual actions (lifestyle changes) can you take to
reduce your personal contribution to climate change?
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