1. The Earth’s Energy Balance CCS 203

2. WEATHER: Meteorological conditions of the next Day – Month
CLIMATE: Long term conditions of the Meteorology over Years - Decades

3. 90% of new energy is in the oceans
FIRST, ABOUT CLIMATE
The Atmosphere is very
Small
90% of new energy is in the oceans

4. Carbon dioxide has risen by 36% since accurate measurements began in 1958
388 ppm (2008)
The photo in the background shows the Mauna Loa Observatory at dusk (courtesy Forrest Mims). This is where, in 1958, Charles David Keeling began his now-famous atmospheric carbon dioxide data set – sometimes called “the Keeling Curve.” The data trend shows carbon dioxide has risen from about 318 parts per million in 1958 to about 388 ppm in The gray “saw-toothed” line shows actual measurements and the red line shows the running mean value.
(Data courtesy NOAA Earth System Research Laboratory)
318 ppm (1958)
Mauna Loa Observatory on Hawai’i

5. “The rise in CO2 is proceeding so slowly that most of us today will, very likely, live out our lives without perceiving that a problem may exist”
Keeling CD, Harris TB, Wilkins EM, Concentration of atmospheric carbon dioxide at 500 and 700 millibars. J. Geophys. Res. 73:

6. Relative measures of Earth’s climate forcings
Natural Process
Solar Irradiance
Carbon Dioxide
Methane, Nitrous Oxide, & Halocarbons
Ozone (Stratospheric & Tropospheric)
Stratospheric Water Vapor
Human Activities
Surface Albedo (Land use & Black carbon on snow)
Aerosol Direct Effect
This graph shows climate scientists’ current estimates of key variables in Earth’s climate system that have changed since 1750 to exert a warming or cooling influence on Earth’s climate — called “climate forcings.” Red bars extending to the right indicate the relative magnitudes of warming influences; blue bars extending to the left indicate the relative magnitudes of cooling influences. The smaller, lightly shaded bars represent the margin of uncertainty in scientists’ estimates.
Climate scientists estimate with very high confidence that the total net forcing of human activities on Earth’s climate since the year 1750 to be +1.6 watts per square meter — a global climate forcing in the warming direction. The subsequent slides in this presentation explain in more detail each of the individual items in this list of climate forcings.
Credit: Intergovernmental Panel on Climate Change’s (IPCC) Fourth Climate Assessment: The Physical Science Basis.
1 Christmas
tree light /m2
Aerosol Cloud Albedo Effect
Airplane Contrails
Total Net Climate Forcing of Human Activities -2 -1 1 2
Radiative Forcing (watts per square meter)

7. Global mean temperatures are rising faster with time Warmest 12 years:
1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000
0.026
0.018
Period Rate
Years /decade

9. Data From Murphy et al 2009, Domingues et al 2008
Graph from

10. Better and longer satellite data about the Sun
Improved assessment:
a) no observed trend in solar irradiance since 1978 using high quality inter-calibrated data; b) spectral information c) solar magnetic flux model rather than proxy data; d) re-evaluation of variations in Sun-like stars.
Solar irradiance forcing much smaller than GHG.

11. John Tyndall Svante Arrhenius
Tyndall, in 1859, demonstrated that in addition to water vapour, carbonic acid (H2CO3) – the form of CO2 dissolved in water – can absorb a great deal of heat energy. He linked this to the possibility of changes in climate, trying to explain why glaciers could advance and retreat.
Experimental verification of work done by Saussure, Fourier, and Pouillet, among others, who had the intuition that “the rays from the sun and fixed stars could reach the earth through the atmosphere more easily than the rays emanating from the earth could get back into space.”
Arrhenius, in 1896, published his theory to explain the ice ages, first speculated that levels of CO2 in the atmosphere could substantially alter surface temperature through the greenhouse effect.

12. Pollution is the Primary Cause
The “Greenhouse gases” (e.g., carbon dioxide, methane, nitrous oxide, CFC’s) trap heat in the earth’s atmosphere.
Solar energy passes through
Radiant
heat is trapped
Greenhouse gases in atmosphere
Infrared
Radiation
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
Science understood
since John Tyndall
Diagrams: Jennifer Allen
Diagrams © Jennifer Allen

13. Energy Transfer Mechanisms
Radiation
Conduction
Convection
There are 3 ways in which energy transfer occurs:
Radiation – transfer through the air (e.g., sun)
Conduction – transfer along/between objects (e.g., touch a hot poker)
Convection – movement caused by convective air movement (e.g., thermals from a stove)
When it is cold, you don’t feel or see any thermal energy coming from it. As you begin to pile on the logs, though, you can start feeling the energy. If you keep adding logs, then it will eventually start to glow a reddish tint.
If you switch to coal, it can eventually get white-hot (visible), but then, you’d better leave, b/c your house is about to explode!

15. RADIATION TRANSFER
REFLECTION
TRANSMISSION
ABSORPTION

16. Important Radiation Laws & Concepts
Net radiation
Rn = incoming – outgoing
Rn = (1- )Is + EL T4(surface) -  T4(sky)
 is albedo, which is the
reflectivity of a surface
fresh snow has a high albedo (0.9)
dark forest has a low albedo (0.05 – 0.15)
light colored soils are in between (0.4 – 0.5)
mean albedo for earth  0.36
Here is what happens to our tree energy-wise.
Total incoming =
direct shortwave radiation from the sun,
diffuse shortwave radiation from the sky,
reflected shortwave radiation from nearby surfaces,
longwave radiation from atmospheric emission,
longwave radiation from nearby surfaces.
Total outgoing = longwave radiation from the surface
Photosynthesis <1% of total incident shortwave solar radiation, so we ignore it.

17. Greenhouse Gases Water vapor (H2O) Carbon dioxide (CO2) Methane (CH4)
Other - Direct
Nitrous oxide (N2O)
Fluorocarbons
Other - Indirect
Carbon monoxide (CO)
Nitrogen oxides (NOx)
Water Vapor:
most abundant and important
varies in concentration from nearly 0% (deserts) – 4% (tropical ocean areas) of lower atmosphere
particularly effective at absorbing long-wave radation from earth’s surface
Think: cloud cover affecting temperature
Most abundant GHG, but not considered in anthropogenic climate change because the atmosphere is so efficient at getting rid of “excess” water vapor through precipitation. Any human influence is “quickly” corrected.
CO2:
2nd most important GHG, 0.038% of atmosphere (380 PPM)
Disproportionately large influence on temperature regulation
Largest emission of GHGs in US (82%)
Projected to grow to 0.06% (600 PPM) by 2050 with a globally averaged temperature increase of deg C ( deg F) in a very short period of time
Fossil fuel emission is only significant source of atmospheric CO2 that is non-natural.
Normally released over millions of years
Important sinks:
Sedimentary rock (geologic time scale) – “Lithification”, very slow, not relevant to current issue
Oceans – have 52X as much C as atmosphere; 19X as much C as combined soils/biosphere; marine phytoplankton take in CO2, release C that eventually sinks to ocean floor and undergoes lithification
Soils – partially decomposed organic matter (humus)
Biosphere (actively growing vegetation, litter) – stores C as it grows
CH4:

18. Greenhouse Gases – Water Vapor
Most abundant and important GHG
Keeps earth warm enough for liquid water to form
Varies in concentration in the lower atmosphere from nearly 0% to 4%
Not considered important in anthropogenic climate change
Naturally correcting
Water Vapor:
most abundant and important
varies in concentration from nearly 0% (deserts) – 4% (tropical ocean areas) of lower atmosphere
particularly effective at absorbing long-wave radation from earth’s surface
Think: cloud cover affecting temperature
Most abundant GHG, but not considered in anthropogenic climate change because the atmosphere is so efficient at getting rid of “excess” water vapor through precipitation. Any human influence is “quickly” corrected.

19. Annual Average Insolation
Top Of
Atmosphere
Annual average insolation at the top of the atmosphere (above) is markedly higher that at Earth's surface (below). The black dots represent the land area required to replace the total primary energy supply with electricity from solar cells.
Earth’s
Surface

20. Light is most concentrated from an overhead source
Light hitting at an angle is less concentrated

21. Why are there seasons? Basically, it is because the Earth is tilted at 23.5°.
At the Vernal and Autumnal Equinox, energy hits the Earth equally in both hemispheres.
At the summer solstice, incoming solar energy is greatest in the Northern Hemisphere (sun is perpendicular to Earth at the Tropic of Cancer).
At the winter solstice, incoming solar energy is greatest in the Southern Hemisphere (sun is perpendicular to Earth at the Tropic of Capricorn).
The Arctic Circle defines the circle on the earth above which, on December 21, the sun doesn’t rise above the horizon.
The Antarctic Circle defines the point on the earth above which, on June 21, the sun doesn’t rise above the horizon.
In the tropics,there is no real change in daylength => no real change in incoming energy => no seasonal change in temperature.
Seasonality comes from the monsoon season.
June-September in India
November-April in Australia

23. Other -volcanoes -meteorites NATURAL VARIABILITY 1911:
Milutin Milankovitch proposes:
All 3 cycles (23, 41, & 100 KYA) together control ice ages
Other
-volcanoes
-meteorites
Credit: Anna Klene

26. Fossil Fuel Emissions: Actual vs. IPCC Scenarios
Projection 2009
Emissions: -2.8%
GDP: %
C intensity: -1.7%
The current financial crisis had a small but probably discernable impact on the emissions growth rate in 2008 (growth rate of 2.0% down from 3.4% per year average over the previous 7 years). Despite this slowdown, fossil fuel emissions continue to track the average of the most carbon-intensive scenario of the Intergovermental Panel on Climate Change. In 2009, we project emissions to decline to levels observed in 2007 with negative growth of -2.8%. Positive growth is expected return in 2011 as the change in global Gross Domestic Product goes positive.
We have estimated emissions for 2009 based on the projection of -1.1% GDP growth rate provided by the International Monetary Fund (October 2009) and assuming a continue global decline in the carbon intensity of the GDP as seen over the last 30 years (-1.7% per year).
Raupach et al. 2007, PNAS, updated; Le Quéré et al. 2009, Nature-geoscience; International Monetary Fund 2009

27. Fossil Fuel CO2 Emissions: Top Emitters
Time
1990 95
2001 05
2009 97 99 03 93
400
800
1200
1600
2000
Carbon Emissions per year
(C tons x 1,000,000)
China
USA
Japan
Russian Fed.
India 07
The biggest increase in fossil fuel emissions in recent years took place in developing countries (with close to 6 billion people) while emissions from developed countries (with less than 1 billion people), on average, show rather steady emissions for the last decade. However, emissions of a number of developed countries declined abruptly in 2009 (USA −6.9%, UK −8.6%, Germany −7%, Japan −11.8%, Russia −8.4%), while emerging economies continued to display rapid growth (China +8%, India +6.2%, South Korea +1.4%).
The countries with highest absolute values of emissions are China, US, India, Russia, and Japan although the emissions per capita in China and India are still a fraction of the emissions in US, Russia and Japan. Prior to 2009, about one quarter of recent growth in emissions in developing countries resulted from the increase in international trade of goods and services produced in developing countries but consumed in developed countries. From a historical perspective, developing countries with 80% of the world’s population account for about one fifth of the cumulative emissions since 1751; the poorest countries in the world, with 800 million people, have contributed less than 1% of these cumulative emissions. Uncertainty of emissions from CO2 fossil fuel is large in some countries.
Global Carbon Project 2010; Data: Gregg Marland, Tom Boden-CDIAC 2010

28. Daily Fossil Fuel Emissions , Jan 3 2002
K. Gurney, Purdue Univ.

29. Image Credit: Robert A. Rohde, Global Warming Art
This figure shows the relative fraction of man-made greenhouse gases coming from each of eight categories of sources, as estimated by the Emission Database for Global Atmospheric Research version 3.2, fast track 2000 project. These values are intended to provide a snapshot of global annual greenhouse gas emissions in the year 2000.
The top panel shows the sum over all greenhouse gases, weighted by their global warming potential over the next 100 years. This consists of 72% carbon dioxide, 18% methane, 8% nitrous oxide and 1% other gases. Lower panels show the comparable information for each of these three primary greenhouse gases, with the same coloring of sectors as used in the top chart. Segments with less than 1% fraction are not labeled.
The increase in greenhouse gas concentrations in the Earth's atmosphere is believed to be the primary cause of global warming.
Image Credit: Robert A. Rohde,
Global Warming Art

30. Per Capita C Emissions
It is time for US leadership here!

31. Variations of the Earth’s surface temperature; 1000 to 2100