Is there really a global warming happening?

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Is there really a global warming happening?
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Review of last lecture

• Air pollution. 2 categories
• 6 types of major pollutants particulates, carbon
  oxides, sulfur dioxides, nitrogen oxides,
  volatile organic compounds, ozone
• Air quality index
• History of air pollution The Medieval pollution,
  The 16th-19th centuries, The 20th century, The
  21st century

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How is scientific consensus achieved on global
warming?

• The Intergovernmental Panel on Climate Change
  (IPCC) is organized by the World Meteorological
  Organization.
• This is a worldwide enterprise that includes
  literally thousands of scientists that are
  involved in producing and critiquing a definitive
  statement on climate change. The political
  controversies have centered around condensed
  summaries produced for policy makers.
• We have had 4 assessments by IPCC so far. The
  last one was completed in 2007, and the next is
  scheduled for completion in summer 2013. Many of
  the figures shown here are taken from the IPCC
  2007 report.

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How are human activities changing the Earths
environment?

• Release of greenhouse gases
• Release of aerosols
• Change of land cover

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Human activities and the Earths environmentI
Release of greenhouse gases - Significant warming
Deuterium (Temperature)

• Global atmospheric concentrations of CO2 and CH4
  have increased markedly as a result of human
  activities since 1750 and now far exceed
  pre-industrial values determined from ice core
  measurements spanning the last 650,000 years!

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Radiative forcing of greenhouse gases
The global net effect of human activities since
1750 has been one of warming.
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Sources of Greenhouse Gases (GHGs)

• CO2 fossil fuel use is the dominant cause of
  CO2 increase

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GHG Emissions by Sector
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GHG emissions per capita
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Human activities and the Earths environment
II Release of aerosols - Slight cooling
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Human activities and the Earths environmentIII
Change of land cover - Slight cooling
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Movie timeWeather Heat
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Observed Changes in Air Temperature Significant
increases
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Observed Changes in Temperature Significant
increases throughout the troposphere and ocean
Mid to upper troposphere
Lower troposphere
Ocean
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Observed Changes in Arctic Sea Ice
Significant melting and positive feedback
Fom National Snow Ice Data Center
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Retreat of Greenland Ice Sheet a huge
contributor to sea level rise today
Greenland is responsible for about 10 of the
observed global sea level rise and accelerating.
Greenland holds 7 m of sea level equivalent.
From UNEP
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Observed Changes in Snow Cover Significant
melting
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Retreat of Mountain Glaciers a major contributor
to sea level rise
Glacier retreat is a world-wide phenomena.

• Will affect water supply for millions
• Kenya/Tanzania
• Northern India
• Andes Mountains

IPCC (2001)
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Tropical glaciers

• Peru's Quelccaya ice cap is the largest in the
  tropics. If it continues to melt at its current
  ratecontracting more than 600 feet (182.8
  meters) a year in some placesit will be gone by
  2100, leaving thousands who rely on its water for
  drinking and electricity high, dry, and in the
  dark.
• From National Geographic

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Observed Changes in Global Sea Level
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Observed Changes in Sea Level Largest
in the western part of ocean basin
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Observed Changes in Water Vapor
Significant increase
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Observed Changes in Precipitation
Significant change in many places
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Change in Mean vs Change in Extremes
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Observed changes in temperature extremes
Less very cold nights and more very warm nights
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Observed changes in precipitation extremes
Increased contribution from very wet days
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Summary

• 3 ways human activities affect the climate.
  Which one warms up (cools down) the climate?
• Rapid increase of greenhouse gases (CO2, CH4,
  N2O) since 1750 far exceed pre-industrial values
  determined from ice core measurements spanning
  the last 650,000 years, which is mainly caused by
  CO2 fossil fuel use.
• Radiation effect of greenhouse gases warming.
• Observed change of mean air temperature, ocean
  temperature, melting of arctic sea ice, Greenland
  ice sheet, snow and glaciers, rising of sea
  level.
• Observed change of extreme events temperature,
  precipitation