Global Warming

Global Warming

Global Warming Climate Change


• Climate change on a global scale is one of most severe threats to our existence in the history of the world.


• Climate change on a global scale is one of most severe threats to our existence in the history of the world.– Is it happening?


• Climate change on a global scale is one of most severe threats to our existence in the history of the world.– Is it happening?– Are we causing it?


• Climate change on a global scale is one of most severe threats to our existence in the history of the world.– Is it happening?– Are we causing it?– Are we contributing to it,

and by what means?


• Climate change on a global scale is one of most severe threats to our existence in the history of the world.– Is it happening?– Are we causing it?– Are we contributing to it,

and by what means?– Can we do anything

about it?

The Earth’s Energy Balance

Greenhouse effect

Our atmospheric gases trap and return a major portion of the heat radiating

from the Earth.

It is a natural, necessary process.

The Earth’s Energy Balance

According to data taken at Mauna Loa, Hawaii since 1958, CO2 levels are on the rise.

Microscopic air bubbles in ice core samples from glaciers can be used to determine changes in greenhouse gas concentrations over time.

Comparing ice core data from Antarctica and Mauna Loa observations, the concentration of carbon dioxide appears to be increasing over time.

The Vostok ice core shows data going back 400,000 years, while other ice cores go back even further (the inset shows data from the figure above). The current concentration of atmospheric carbon dioxide is 100 ppm higher than any time in the last million years.

Average global surface temperatures have increased since 1880.

The red bars indicate average temperatures for the year while the black error bars show the range for each year. The blue line is the 5-year moving average.

Ice Cores as Temperature Recordings



DD D D D D D106°

Ice Cores as Temperature RecordingsProperty D2O (Heavy water) H2O (Light water)

Freezing point (°C) 3.82 0.0

Boiling point (°C) 101.4 100.0

Density at STP (g/mL) 1.1056 0.9982

Temp. of maximum density (°C) 11.6 4.0

Heat of fusion (cal/mol) 1,515 1,436

Heat of vaporization (cal/mol) 10,864 10,515

pH (at 25°C) 7.41 (sometimes "pD") 7.00

Data from Wikipedia, “Heavy Water”


• So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water


• So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water– And thus in the ice in Antarctica



• And likewise, as atmospheric temperature drops, so does the concentration of heavy water in the air, and the concentration in the ice increases



• And likewise, as atmospheric temperature drops, so does the concentration of heavy water in the air, and the concentration in the ice increases

• And one can do the same for the oxygen in water– And in fossils from around the world

Global temperatures for 2006 (in oC) relative to the 1951–1980 average. The most dramatic changes have been observed in the higher latitudes (dark red areas).

The concentration of carbon dioxide (blue) and the global temperature (red) are well correlated over the past 400,000 years as derived from ice core data. The CO2 levels are currently higher than ANY time in the part 400,000 years!

Representations of methane

Lewis structuresshow connectivity.

This Lewis structure is drawn in 3-D.

Space-filling

CH4 = molecular formula; does not express connectivity

Structural formulas show how atoms are connected:

Four electron pairs as far from each other as possible indicates a tetrahedral arrangement.

A tetrahedral- shaped

molecule has bond angles

of 109.5o

Valence Shell Electron Pair Repulsion Theory

Consider methane (CH4), where the central carbon atom has 4 electron pairs around it:

3.3

The legs and shaft of a

music stand are like the bonds of a tetrahedral molecule.


The 3-D shape of a molecule affects its ability to absorb IR radiation.


Assumes that the most stable molecular shape has the electron pairs surrounding a central atom as far away from one another as possible.

The central atom (O) in H2O also has four electron pairs around it.

But unlike methane, two electron pairs are bonding and two are nonbonding.

The electron pairs are tetrahedrally arranged, but the shape is described only in terms of the atoms present: water is said to be bent shaped.

The nonbonding

electron pairs take up more

space than bonding

pairs, so the H-to-O-to-H bond angle is compressed.

We can use the VSEPR model to allow us to predict the shape of other molecules.

Number of electron pairs around central atom

Shape of molecule Bond angle

4 electron pairs, all bonding: CH4, CF4, CF3Cl, CF2Cl2

tetrahedral 109.5o

4 electron pairs, three bonding, one nonbonding:

NH3, PCl3

Triangular pyramid about 107o

4 electron pairs, two bonding, two nonbonding:

H2O, H2Sbent about 105o

Other predictions can be made based on other electron pair arrangements.

Now look at the central atom of CO2:

Two groups of four electrons each are associated with the central atom.

The two groups of electrons will be 180o from each other: theCO2 molecule is linear.

Molecular vibrations in CO2. Each spring represents a C=O bond.

(a) = no net change in dipole – no IR absorption.

(b, c, d) = see a net change in dipole (charge distribution), so these account for IR absorption.

Molecular geometry and absorption of IR radiation

The infrared spectrum for CO2

Wavenumber (mm–1) = 1______wavelength (mm)

The infrared spectrum for CO2

As IR radiation is

absorbed, the amount of

radiation that makes it

through the sample is reduced.

Molecular response to different types of radiation

The carbon cycle

CO2 emission sources by end use:

Global Warming Potential (GWP) represents the relative contribution of a molecule of an

atmospheric gas to global warming.

Amplification of Greenhouse Effect:

Global Warming

What we know:

1. CO2 contributes to an elevated global temperature.

2. The concentration of CO2 in the atmosphere has been increasing over the past century.

3. The increase of atmospheric CO2 is a consequence of human activity.

4. Average global temperature has increased over the past century.

Amplification of Greenhouse Effect:

Global Warming

What may be true:

1. CO2 and other gases generated by human activity are responsible for the temperature increase.

2. The average global temperature will continue to rise as emissions of anthropogenic greenhouse gases increase.

Radiative Forcings are factors that affect the balance of Earth’s incoming and outgoing radiation.

Climate Models are used to predict annual global mean surface temperatures.

Blue bands = predicted temperature range using natural forcings onlyPink bands = temperature range with both natural and anthropogenic forcings

Models can also be used to predict future global temperatures.

Black line = data for the 20th centuryOther lines = projected 21st century temperatures based on different socioeconomic

assumptions

Intergovernmental Panel on Climate Change (IPCC) Recognizing the problem of potential global climate change, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. It is open to all members of the UN and WMO.

Conclusions from the 2007 IPCC Report

NASA Study: The Arctic warming study, appearing in the November 1, 2003, issue of the American Meteorological Society's Journal of Climate, showed that compared to the 1980s, most of the Arctic warmed significantly over the last decade, with the biggest temperature increases occurring over North America.

Perennial, or year-round, sea ice in the Arctic is declining at a rate of nine percent per decade.

Loss of Polar Ice Cap

1979

2003

Loss of Polar Ice Cap

As the oceans warm and ice thins, more solar energy is absorbed by the water, creating positive feedbacks that lead to further melting.

Such dynamics can change the temperature of ocean layers, impact ocean circulation and salinity, change marine habitats, and widen shipping lanes.

1979

2003

Sea Level Rise

• The melting of the polar ice has caused a steady rise in ocean levels– Measured as 1.5 mm per year since 1961

• Increase not uniform across the globe, so places where the rises have been seen are actually larger

• Rises that large are responsible for both erosion and storm surge severity.

More Extreme Weather to Come

• Increasing temperature means increasing energy deposition into the climate– More energy means stronger storms– Wildfire and flood frequency has increased on every

continent in the last several decades

Changes in Ocean Chemistry

• As the atmospheric concentration of CO2 rises, the amount absorbed into the ocean also increases

2 2 2 3CO H O H CO

Changes in Ocean Chemistry

• As the atmospheric concentration of CO2 rises, the amount absorbed into the ocean also increases

• 1 million tons absorbed every day!!!– About a third of what we currently generate

• The amount of CO2 absorbed raises the acidity (reduces the pH) of the ocean.– Reduces shell formation for shell fish, skeletons for most

other fish and plankton

2 2 2 3CO H O H CO

Loss of Biodiversity

• Climate change and deforestation are eliminating species at an unprecedented rate.– Estimated to be 1000 times greater than at any time in the

last 65 million years.• The most optimistic estimate is that 20% of the

plants and animals on earth will be threatened with extinction by 2050.

One potential method for mitigation is CO2 sequestration.

Carbon Sequestering

• About two dozen projects around the globe– Only 4 are in commercial operation

• Underscores the extreme costs and technological difficulties involved

• Three capture CO2 from natural gas wells, transporting it and injecting it into other geological features.

• The largest takes CO2 from a coal power plant in North Dakota and injects it into oil drilling wells in Saskatchewan, Canada.

Pressure from the injected gas forces more oil out of the wells, giving a secondary benefit!

Carbon Sequestering

• About two dozen projects around the globe– Only 4 are in commercial operation

• Underscores the extreme costs and technological difficulties involved

• Three capture CO2 from natural gas wells, transporting it and injecting it into other geological features.

• The largest takes CO2 from a coal power plant in North Dakota and injects it into oil drilling wells in Saskatchewan, Canada.

Pressure from the injected gas forces more oil out of the wells, giving a secondary benefit!

– Combined, the four projects sequester about 5 million tons a year

Kyoto Protocol – 1997 Conference• Intergovernmental Panel on Climate Change

(IPCC) certified the scientific basis of the greenhouse effect.

• Kyoto Protocol established goals to stabilize and reduce atmospheric greenhouse gases.

• Emission targets set to reduce emissions of six greenhouse gases from 1990 levels.

(CO2, CH4, NO, HFCs, PFCs, and SF6)

• Trading of emission credits allowed.

A Cap-and-Trade System can be used to limit CO2 emissions.

Cap and Trade

• Roundly dismissed by current Congress as unnecessary

• Many state-level initiatives have been adopted– 10 northeastern states have created the RGGI – the

Regional Greenhouse Gas Initiative – and have adopted a cap and trade system that capped emissions at 2009 levels and aim at a reduction of 10% by 2019

– The Midwestern Regional Greenhouse Gas Reduction Accord have developed a multi-sector cap and trade system to help meet a 60-80% long term reduction goal.

Cap and Trade

• Roundly dismissed by current Congress as unnecessary

• At the local level, the US Mayors’ Climate Protection Agreement committed to cutting emissions to meet the targets of the Kyoto Protocol.– 227 cities!– Some of the largest cities in the Northeast, the Great Lakes

region, and the West Coast.• Representing 44 million people!

Global Warming

Documents

global scale

antarctica ice cores

ice increasesice cores

temperature recordingsso

ice core data

ocean waterice cores

severe threats

heavy waterice cores