Chapter 3 Houghton - Greenhouse gases

What are some causes of increased amounts of CO2 in the atmosphere?

- Burning of fossil fuels - Land-use change (deforestation) - Cement manufacturing

Which greenhouse gases is the most important of the most important gas which in increasing in atmospheric concentration because of human activities? How much has it contributed to the advanced greenhouse effect?

Carbon dioxide - has contributed to about 74% of advanced greenhouse effect

Why do we see seasonality in carbon dioxide graphs?

Carbon dioxide is removed from the atmosphere via photosynthesis during growing periods and released during the winter as plants die off causing a net increase

CFCs

Chlorofluorocarbons. -> greenhouse gases - They have a really long live span because they are very unreactive which means that even though we aren't using them anymore, they will continue to hang around in the atmosphere - Man made chemicals used as coolants and propellants in aerosols. - Measured in ppb (parts per billion) -Potent greenhouse gases that also lead to depletion of the ozone layer.

How is studying the amounts of the different carbon isotopes in the atmosphere helpful when studying global climate change?

Depending on the ratio of different carbon isotopes in the atmosphere, we can tell where the carbon likely came from

Discuss how ozone is both "good" and "bad" for the planet

Good - makes up the ozone layer and absorbs ultraviolet radiation in the atmosphere which prevents it from reaching us on earth (shields us from harmful radiation from the sun) Bad - it's a greenhouse gas which means it's speeding up global warming

Describe the biological pump

How carbon dioxide is transferred from the atmosphere to the deep ocean... - Lots of plant life in the ocean which intakes carbon dioxide from the atmosphere during photosynthesis -These plants are either eaten or die - As plankton and plants die, they release carbon dioxide which sinks to the deeper ocean where it stays for hundreds of thousands of years -Note: as think carbon sinks down to the ocean, more carbon from the atmosphere can dissolve into the surface ocean for the system to regain equilibrium

Why is the effect of higher temperatures on respiration a positive feedback loop?

It increases the amount of CO2 released into the atmosphere which in turn speeds up climate change

What is the main component of natural gas?

Methane

Why is the effect of methane on the atmosphere not negligible compared to that of carbon dioxide considering that there is a much larger concentration of CO2 in the atmosphere?

The enhanced greenhouse effect caused by a molecule of methane is about 8 times that of a molecule of CO2

The lifetime of a carbon dioxide molecule in the atmosphere before it is exchanged with the ocean is typically less than a year, while the time taken for an increase in carbon dioxide concentration from fossil fuel burning to diminish substantially is typically many years. Why?

Unlike other greenhouse gases, carbon is not destroyed in the atmosphere. Rather, it is redistributed to different carbon reservoirs which hold the carbon fro varying periods of time before it is released back into the atmosphere. Therefore, it takes awhile for carbon dioxide concentration to diminish.

How can we measure how much carbon dioxide was in the atmosphere hundreds and thousands of years ago?

Using ice cores

Define biota (biotic community)

assemblage of living entities (plant, animals, microbes) - anything living on the land

Name the process that the textbook claims was important in determining the changes of carbon dioxide concentration in both atmosphere and the ocean during ice ages?

biological pump

Define isotopes

chemically identical forms of the same element but with different atomic weights

According to the text book, a negative ocean or land to atmosphere CO2 flux is equivalent to a gain or a loss of carbon by these reservoirs?

gain

Define the carbon dioxide "fertilization" effect

increased carbon dioxide in the atmosphere leads to growth in some plants

Describe what happens in the upper ocean when CO2 concentrations increase in the atmosphere.

- Carbon dioxide is quickly dissolved into the ocean so that roughly one tenth of the new carbon is added (this is a rapid process) - any change in the atmosphere results in 1/10th of that changes in the ocean

What was the Montreal Protocol?

An international treaty requiring all countries to reduce CFC's to fix the ozone hole

Which carbon isotope is most common?

C12 (makes up 98.9% of ordinary carbon)

Which two gases contribute the most to global warming?

CO2 and methane

Is the carbon dioxide fertilization effect a positive or negative feedback loop? Why?

Negative b/c as the CO2 levels in the atmosphere increase, the amount of carbon dioxide that plants take in also increases, which reduces the amount of CO2 in the atmosphere and slows the rate of global warming

Is carbon dioxide destroyed in the atmosphere?

No, rather it is redistributed throughout to different reservoirs

Are forest fires caused by warmer/dryer conditions an example of a positive or negative feedback loop?

Positive

"a warmer regime will be associated on average with weaker overturning in the ocean and therefore with reduced carbon dioxide uptake" (38) - what kind of feedback loop is this?

Positive feedback loop

Has the biological pump's activity decreased, increased, or remain constant throughout the last century in response to increased carbon dioxide concentrations in the atmosphere?

Remained the same, it seems unaffected by the increase

What will warmer temperatures likely do to the biological pump?

Slow it down because the water will not circulate as much

As temperatures increase, methane is released from wetlands and from very large methane reservoirs trapped in a hydrate form. Is this an example of a positive or a negative feedback?

positive

Is the plankton multiplier in the ocean an example of a positive or a negative feedback loop?

positive

Reduction of growth in forests due to stress caused by climate change is an example of what type of feedback loop?

positive

Define solubility pump

process whereby carbon dioxide is gradually drawn from the atmosphere into the ocean's lower levels

Define radiative forcing

the change in average net radiation at the top of the troposphere which occurs because of a change in the concentration of a greenhouse gas or because of some other change in the overall climate system

What does ozone shield us from?

ultraviolet radiation from the sun

What is the main natural source of methane?

wetlands