global warming - california state university, northridgethe combined global land and ocean average...

Understanding Global Warming

Spring 2014California State University, Northridge

Thursday, January 23, 2014

The combined global land and ocean average surface temperature for January–November 2013 was 0.62°C above the 20th century average of 14.0°C, tying with 2002 as the fourth warmest such period on record. -- NOAA

Global Warming is Real


Temperature Anomalies Relative to 20th Century Average


2012, European Space Agency: 900 km3 sea ice lost each year since 2004. Arctic sea ice could vanish in 10 years.

Disappearance of Arctic Sea Ice


Arctic sea ice on 26 Aug 2012. Sea ice dipped to its smallest extent ever recorded in more than three decades of satellite measurements: Scientific

Visualization Studio, NASA Goddard Space Flight Center

Disappearance of Arctic Sea Ice


CO2 Concentration over Time

Carbon dioxide concentration May 2013: 400 ppm


CO2 Concentration Keeling Curve


2013 Intergovernmental Panel on Climate Change (IPCC) (2,000 scientists from154 countries)

• Warming of the climate system is unequivocal. 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. “Human influence on the climate system is clear.”

• The globally averaged combined land and ocean surface temperature show a warming of 0.85°C from 1880 to 2012

• The atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. Carbon dioxide concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification


Global and continental evolution of the temperature since 1900, based on measurements (bold line) and ensemble simulations with coupled climate models (bands). Only simulations with a complete forcing which includes changes in greenhouse gases, aerosols, observed volcanic eruptions and variable solar radiation, show reasonable agreement with the observations over the entire 20th century. In case the effect of anthropogenic forcings (greenhouse gases, aerosols) on the radiative balance is not taken into account, the global increase in temperature cannot be simulated. (Figure from IPCC 2007, Summary for Policymakers, www.ipcc.ch)

IPCC Climate Models


http://www.ipcc.ch

http://www.ipcc.ch

MIT and Penn State Study, 2012

• Warns that Earth may be near tipping point, pushing planet to calamitous and irreversible changes

Nature article by group of 22 scientists, 2012

• Worldwide Average Temperature increase of 9°F by 2100

• Arctic will warm three times as fast as 2007 IPCC study found, along with greater ocean warming, sea level rise, and extreme weather events


Study aided by supercomputer more precise than previous climate models for the region. Roughly 1 quintillion calculations over a period of six months to assess aspects of 25 global warming models applicable to Southern California.

Findings:

UCLA Center for Climate Change Solutions 2012

• By mid-century, the number of days with temperatures above 95 degrees each year will triple in downtown L.A., and quadruple in portions of the San Fernando Valley.

• The hottest of those days will break records.

National Research Council, Ca, Or, Wa Study 2012

Study, commissioned by federal agencies and 3 states predicts 5 1/2 feet sea level rise in California by 2100.


U.S. Global Change Research Program

Draft National Climate Assessment(2013)

U.S. average temperature has increased by about 1.5°F since 1895; more than 80% of this increase has occurred since 1980. The most recent decade was the nation’s hottest on record.

U.S. temperatures will continue to rise, with the next few decades projected to see another 2°F to 4°F of warming in most areas. The amount of warming by the end of the century is projected to correspond closely to the cumulative global emissions of greenhouse gases up to that time: roughly 3°F to 5°F under a lower emissions scenario involving substantial reductions in emissions after 2050, and 5°F to 10°F for a higher emissions scenario assuming continued increases in emissions.


James Hansen, Makiko Sato, Gary Russell and Pushker Kharecha

Climate sensitivity, sea level and atmospheric carbon dioxide

Phil. Trans. R. Soc. A 2013 371, Sept 2013Burning all fossil fuels would produce a different, practically uninhabitable, planet. Recent updates of potential reserves, including unconventional fossil fuels (such as tar sands, tar shale and hydrofracking-derived shale gas) in addition to conventional oil, gas and coal, suggest that 5 × CO2 (1400 ppm) is indeed feasible.

Our calculated global warming in this case is 16°C, with warming at the poles approximately 30°C. Calculated warming over land areas averages approximately 20°C.

More ominously, global warming of that magnitude would make most of the planet uninhabitable by humans. The human body generates about 100 W of metabolic heat that must be carried away to maintain a core body temperature near 37°C, which implies that sustained wet bulb temperatures above 35°C can result in lethal hyperthermia.

A warming of 10–12°C would put most of today’s world population in regions with wet a bulb temperature above 35°C.

We conclude that the large climate change from burning all fossil fuels would threaten the biological health and survival of humanity, making policies that rely substantially on adaptation inadequate.


Corporate Response

Reuters (Oct 15, 2013) The United States has overtaken Saudi Arabia to become the world's biggest oil producer.

U.S. output, which includes natural gas liquids and biofuels, has swelled 3.2 million barrels per day since 2009.

It was the latest milestone for the U.S. oil sector caused by the shale revolution [fracking], which has upended global oil trade.

Corporations spend $674 billion in 2012 on carbon exploration and extraction


http://www.cnbc.com/id/100364827

http://www.cnbc.com/id/100364827

http://www.reuters.com/places/saudi-arabia

http://www.reuters.com/places/saudi-arabia

The Climate System is Complicated . . .


...But the key ingredient to Global

Warming is the greenhouse effect


Visible Spectrum

Low Frequency High Frequency

R o y G B i v


Electromagnetic Spectrum

Infrared Ultraviolet


Radiation and Matter


... is the ratio of reflected sunlight to incident sunlight.

Albedo...


Figure 6. White, ice-covered polar regions are important for reflecting much of the incoming solarradiation during summer, whereas sea water absorbs most of the incident radiation. The

reflectance, or albedo, of the sea ice pack is largely determined by melt ponds on the surface, likethose shown on the right in the Arctic in June 2007. Melt pond evolution itself is largely

determined by the fluid permeability of the sea ice below, as well as by the Sun’s rays.

Figure 7. The rich Antarctic marine ecosystem is supported by photosynthetic algae (d), whichgive sea ice a brownish or yellowish color (e). Nutrient replenishment for these microbes is

controlled by fluid flow through the porous brine microstructure. Krill (c) feed on algae, Emperorpenguins (a) feed on krill, and killer whales (b) spy-hop looking for penguins to eat.

(or elementary bounds), were obtained almost one

hundred years ago by Wiener:

(4)1

!"1+

1!!"2

" "# " !"1 + (1!!)"2.

The bounds are optimal, since laminates parallel

to the field realize the upper bound, as shown in

Figure 10(a), while laminates perpendicular to thefield realize the lower bound.

For the fluid problem, we ask what configu-ration of the pores maximizes k. Intuitively, thebest arrangement to maximize k is in verticalpipes of appropriate radii, as shown in Figure10(b), where in the fluid problem a length scalenot present for electrical conductivity arises. This

568 Notices of the AMS Volume 56, Number 5

The albedo of snow-covered ice is close to 1 (larger than 0.8); the albedo of sea water is close to zero (less than 0.1).

.

Earth’s Planetary Albedo ≈ 0.3


What happens to the 70% of solar radiation that is

not reflected back into space?


Heat and LightThe temperature of an object determines the

frequency of radiation it emits.


How does a green house work?


Green house gases and radiation

Molecular structure and quantum mechanical properties determine which

frequencies can be absorbed. Green house gases absorb infrared light.

H2O

CO2


Absorption Bands of

Atmospheric gases


Light from the SunPhotosphere: ~ 6000° K


Some Vocabulary

• Energy: 1 Joule = 0.74 foot-pounds

• Power: 1 Watt = 1 Joule/second

• Power from Sun (top of atm) 1370 W/m2

• Average power Earth surface: 240 W/m2

(approx 1000 W/m2 at noon)


Sun vs Earth


Radiation Spectrum: Sun vs Earth


Radiative Power: Sun

vs Earth


Green House Effect


Current level of radiative forcing (IPCC) is 2.3 watts per square meter

Taking into account total land area of the Earth, this gives a total warming effect of about 1150 terawatts. World’s average rate of energy consumption, which is about 15 terawatts.


Want to learn more?

CSUN, with support from NASA, is developing a new program and courses for

the study of climate science.

www.csun.edu/climate


http://www.csun.edu/climate

http://www.csun.edu/climate

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