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