Weather Condition of the atmosphere at any particular time and place

Air temperature, air pressure, humidity, clouds, precipitation, visibility, wind

Climate Accumulation of daily and seasonal weather events over a long period of time

“Average weather”

Wisconsin Initiative on Climate Change Impacts 2011

What is the Greenhouse

Effect?

Earth: 400 ppm CO2

Venus: 965,000 ppm CO2

Venus: 460C, hotter than Mercury, despite 1/4 of solar irradiance

Both Good and Bad

Which is the most abundant

greenhouse gas on Earth?

National Center for Atmospheric Research

Primary greenhouse gases:

- Water vapor (#1) (<1 year)

- Carbon dioxide (100s years)

- Methane (10 years)

- Nitrous oxide (100 years)

- Ozone (<1 year)

- Hydrofluorocarbons (1000s years)

- Chlorofluorocarbons (100s years)

National Center for Atmospheric Research

Global warming art

Year2000

#1

#2

#3

Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5); NOAA; Florida Center for Environmental Studies

Atmospheric Levels of Carbon Dioxide Atmospheric Levels of Methane

Accelerated trend1959-1963: +0.76 ppm/year2009-2013: +2.18 ppm/year

Concentrations are increasingPre-Industrial Era ≈ 280 ppmJune 2014 ≈ 400 ppm(keelingcurve.ucsd.edu)

Note the distinct seasonal cycle:

“Breath of the biosphere”

Fleagle & Businger

Absorption Spectrum: Amount of Radiation Absorbed at a Given Wavelength

VISIBLEULTRAVIOLET

(Shortwave)INFRARED(Longwave)

Greenhouse gases primarily absorb longwave (infrared) radiation

Not absorbed Not absorbe

d

Absorbed

Greenhouse gases

GreenhouseEffect

Some of the infraredradiation passes through the atmosphere but most is absorbed and re-emitted in all directions by greenhousegas molecules and clouds. The effect of this is to warm the Earth’s surface and the lower atmosphere (IPCC AR4 WG1).

Shortw

av

e

Long

wav

e

Sun = hot = emits

shortwave (UV)

radiation

Earth = cool = emits longwave (IR)

radiation

Wien’s Law: Wavelength inversely

related to temperature

National Climate Assessment; Global Carbon Project; Boden et al. 2012

Human-induced changes in the global carbon budget since the beginning of the Industrial Revolution. Emissions from fossil fuel burning are the dominant cause of the steep rise from 1850 to 2012.

Global carbon emissions from burning coal, oil, and gas and producing cement during 1850-2009. These emissions account for about 80% of the total emissions of carbon from human activities, with land-use changes accounting for the other 20%.

Patz et al. 2007

Carbon dioxide

emissions

Predicted mortality for 2000-2030 due

to malaria, malnutrition,

diarrhea, flooding related to climate

change

Climate change is an ethics issue

China 26%U.S. 17%European Union 13%

China 26%

U.S. 17%

European Union13%

IPCC AR5

Each decade is subsequently warmer

“Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983-2012 was likely the warmest 30-year period of the last 1400 years.” – IPCC AR5

“The globally averaged combined land and ocean surface temperature data….show a warming of 0.85°C over the period of 1880-2012.” – IPCC AR5

Note the distinct interannual and decadal variability, in addition to the long-term trend

Claim: But this last winter was brutally cold, so global warming is not happening.

Surface air temperature anomalies (°C) during December 2013 – April 2014Only cold over central North America….most other places in the world were warm, especially the Arctic.

Histogram of surface air temperature anomalies (°C) during December 2013 – April 2014 for all global grid cellsDuring those 5 months, 66% of the world was warmer than normal and only 34% was colder than normal.