observed global climate change. review of last lecture tropical climate: mean state: the two basic...
TRANSCRIPT
Observed Global Climate Change
Review of last lectureReview of last lecture
Tropical climate:
• Mean state: The two basic regions of SST? Which region has stronger rainfall? What is the Walker circulation?
• Mean state: Two types of ocean upwelling, ocean-atmosphere feedback
• El Nino and La Nina: Which region has warm SST anomaly during El Nino? 4-year period.
• Land-sea contrasts: seasonal monsoon
Extratropical climate:
• Mean state: westerly winds, polar vortex
• What is the primary way El Nino affect extratropics? (PNA)
• The oscillations associated with strengthening/weakening of polar vortex: AO, AAO
• The Intergovernmental Panel on Climate Change (IPCC) is organized by the World Meteorological Organization, and endorsed by the United Nations General Assembly.
• 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 5 assessments by IPCC so far.• First Assessment Report (1990)• Second Assessment Report (1995) • Third Assessment Report (2001)• Fourth Assessment Report (2007): Nobel Peace
Prize • Fifth Assessment Report (2013-2014)
How is scientific consensus achieved on global warming?
How do human activities change the global climate?
Human beings are changing the global climate system in three different ways:
• Release or cleanse greenhouse gases• Release or cleanse pollutants (aerosols) • Change land cover (deforestation and urbanization)
The most common atmospheric circulation structure
L
H
H
L
HeatingCoolingor No Heating
Imbalance of heating Imbalance of temperature Imbalance of pressure Wind
Radiation Convection Conduction
Latent/Sensible
BiosphereLand/Ocean/Ice/
Stratosphere Feedback
Greenhouse Gases
Pollution
Clouds Precipitation (Latent heat)
SpiritualSocialHealthEconomy
Observed change of greenhouse gases
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!
Radiative heating of greenhouse gases
Source of greenhouse gases
CO2 fossil fuel use is the dominant cause of CO2 increase
GHG Emissions by Sector
Greenhouse gas emissions per capita
The developed countries and developing countries contribute almost equally to the emissions of GHGs.
Video: A global warning?https://www.youtube.com/watch?v=t_miunplJK4
Observed Change in Global Temperature: Significant warming
Global map of temperature change: Largest warming in Arctic (“Arctic amplification”)
Larger warming over land than ocean
Global map of snow/ice cover
Observed Melting of Arctic Sea Ice
http://arctic.atmos.uiuc.edu/cryosphere/multiyear.ice.quikscat.mov
Melting of Greenland Ice Sheet – A huge contributor to sea level rise today
Greenland is responsible for about 10% of the observed global sea level riseand accelerating. Greenland holds 7 m of sea level equivalent.
Observed Changes in Snow Cover: Significant melting
Melting of Mountain Glaciers: a major contributor to sea level rise
IPCC (2001)
Glacier retreat is a world-wide phenomena.
Will affect water supply for millions:• Kenya/Tanzania• Northern India• Andes Mountains
1917 2008
1978 2004
Qori Kalis Glacier, Peru
Pedersen Glacier, Kenai Fjords National Park, Alaska
Pasterze Glacier, Austria
1875 2004
Observed Changes in Global Sea Level
Observed Changes in Sea Level Largest in the western part of ocean basin
Summary: Observed significant changes
Change in Mean vs Change in Extremes
Observed changes in precipitation extremes: Increased contribution from very wet days
Summary: Observed significant changes in extreme weather
Summary
• 3 ways human activities affect 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. Lead to strong radiative heating.
• The developed countries and developing countries contribute almost equally to the emissions of GHGs.
• 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: extreme precipitation events, heat waves, strongest hurricanes
Works cited• http://www.earthtimes.org/environment/greenhouse-gases/
• National Snow & Ice Data Center
• http://sciencewithme.com/learn-about-global-warming/
• http://www.chemistryland.com/CHM107Lab/Exp04_biodiesel/BiodieselLab/Exp4Biodiesel.html
• http://www.eea.europa.eu/data-and-maps/indicators/greenland-ice-sheet/greenland-ice-sheet-assessment-published
• http://arctic.atmos.uiuc.edu/cryosphere/
• http://www.treehugger.com/clean-technology/yahoos-5-stunning-before-and-after-pictures-of-melting-glaciers.html
• http://www.detectingdesign.com/ancientice.html
• http://nca2009.globalchange.gov/human-health
• http://latino.foxnews.com/latino/news/2012/10/30/hurricane-sandy-floods-new-york-city-photos-show-devastation/
• http://ocean.nationalgeographic.com/ocean/critical-issues-sea-level-rise/
• http://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/multisensor_global_snow_ice.html