Transcript Ken Hu - Cal Poly

Modern Global Climate Change
by Thomas R. Karl and Kevin E. Trenberth
Summary: Ken Hu
Critique: Roy Chen
Summary
Abstract of the article
• The article illustrates the relationship
between human influences and modern
global climate change. It also predicts the
future base on the past information and
global climate models.
Main Descriptions
• Human influences on climate
• The resulting temperature and
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precipitation change
The time scale of response
Important processes involved
Climate models
Observation and information systems
Human Influences on climate
• Global Climate change
• Regional Climate change
Global Influences change
• Greenhouse gases increase
• Aerosols are removed
Greenhouse gases increase
• Reason(s): Burning of fossil fuels and
methane and nitrous oxide from multiple
human activities.
• For example: Carbon dioxide has
increased 31 since preindustrial times
• Half of the increase has been since 1965.
• Result(s): global warming
CO2 and T (Global) VS Time
Aerosols are removed
• Reason(s): Fuel burning
• Results(s):
1. Either net cooling or net heating
2. Directly reflecting solar radiation and
indirectly by changing the reflective
properties of clouds and their lifetime
Regional Climate change
• Changing in landuse.
• Reason(s): Urbanization and agricultural
practices.
• For example: Large-scale deforestation
and desertification in Amazonia and the
Sahel
• Result(s): “concrete jungle” and its effects
on heat retention, runoff, and pollution,
resulting in urban heat islands.
Human influence on global climate
affects worldwide
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Global warning
Surface moisture
Land-surface drying
More atmospheric water vapor
Human influence on global climate
affects regionally
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Wild fire
Heat stress
Vegetation changes
Sea level rise
The time scale of response and
important processes involved
• Human-induced climate change is
projected to be much faster than most
natural processes.
• Freshwater discharges
• Greenland and Antarctica may not be
stable Raising sea level
Concepts of the climate system
• Climate system is complicated
• Three major feedback affect the climate
system
• Water vapor feedback
• Cloud feedback
• Ice-albedo feedback
Climate models
• The primary tools for predicting future
climate
• Fully coupled, mathematical, computerbase models of physics, chemistry, and
biology of the atmosphere, land surface,
oceans and cryosphere and their
interactions with each other and with the
sun and other influences.
Example of a modeling the climate
system
Two atmosphere-ocean system
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El Niño
North Atlantic Oscillation (NAO)
El Niño is linked to the global heating
NAO affects the severity of winter
temperatures and precipitation in Europe
and eastern North America.
Observation and information
systems
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Simulate the past climate
Comprehensive
Long term climate-related data sets
Observing systems that deliver data free
of time-dependent biases
• Global monitoring
Space-based
Surface-based
Conclusion of the article
• The article describes that we need better
observation and system to project the
future global climate change. The climate
change is international greatest challenge.
Critique:
Author Credibility
Thomas R. Karl
• Director of the NOAA National Climatic
Data Center, in Asheville, N.C
• Fellow of the AMS and the American
Geophysical union
Kevin E. Trenberth
• Fellow of the American Meteorological
Society (AMS)
• Fellow of the American Association for
Advancement of Science.
Author Opinions:
• Climate change is a global issue.
• Human activities alter the climate change.
For example, global warming effect that
results from the burning fossil fuels
(energy uses).
• We are entering the unknown with our
Climate.
• We need improve climate observing in
order to analyze the global climate
change.
• Climate change may be our greatest
challenge. We should work together to
overcome this challenge (global
Cooperation and action.
Paper Strength
• Well developed and organized.
• First, authors analyze the some factors
cause the climate change.
• Greenhouse gases emission and
landscape change ( from humans activities
directly)
• Climate change complicated and amplified
by water vapor, cloud, Ice-albedo feedback
• NAO and El Niño. ( Ocean current
systems)
• Second, authors discuss the challenges to
analyze uncertainty of climate change.
• Scientists need to improve observing
systems and global simulation model by
integrate technologies.
Paper weakness
• Authors did not discuss the efforts to stop
global warming effect. For instance, U.N
global climate treaty.
• U.S did not to produce significant
reduction in greenhouse gas emissions,
which cause global warming.
Question