Climate Feedbacks
From catastrophic chain-reactions which could push us into dangerous climate change, to cooling effects which
balance out global warming, climate feedbacks are an important area of research for scientists.
What is a climate feedback? This happens when a change in our climate causes an impact which changes our
climate further — a knock-on effect which feeds back into our climate. There can be both negative and positive
feedbacks:
Negative feedback — this is an impact which offsets the prevailing change in climate. Under global warming,
this would create a cooling effect, balancing out the changes. If the climate was getting colder, it would create a
heating effect.
Positive feedback — this is an impact which increases the change in the climate. It would add to global
warming by creating further heating or, if our climate was cooling, would cool the climate further.
I. Read through the following examples of various feedbacks. Decide whether they are negative or positive,
explain your reasoning using AP level writing and complete sentences. (18 pts)
II. Illustrate feedback loops # 1 and # 9, plus one more of your choosing, (that is 3 feed back loops in total) in a
creative way. (30 pts for original, neat, well-thought out, visually pleasing, and detailed feedback loops)
1. Ice caps at the north and south poles are very reflective -- the ice reflects light and heat rather than
absorbing it. If global warming occurs, then the increase in temperature will cause polar ice to melt, and
the bare dark ground will absorb rather than reflect heat. This additional absorption of heat will further
boost the temperature of the earth. Is this a positive or negative feedback loop? Explain.
2. Carbon dioxide is considered a "greenhouse gas" since it absorbs heat that would otherwise
dissipate out into space. If there is more carbon dioxide in the atmosphere, global temperatures
are likely to increase. It is possible that plants will respond to the increased carbon dioxide and
increased temperatures with an increase in photosynthesis. Is this a positive or negative
feedback loop? Explain.
3. We know that warm water holds less dissolved gas -- that's why a soda pop goes flat when it
gets warm. Normally, there is a great deal of dissolved carbon dioxide in cold ocean water. As
the temperature of the ocean increases this reduces its capacity to absorb CO2. Is this a positive
or negative feedback loop? Explain.
4. As air gets warmer, its capacity to hold moisture increases. Our atmosphere is getting warmer
because of climate change and, as a result, is holding more water vapour, a greenhouse gas. Is
this a positive or a negative feedback? Explain
The way climate change affects clouds could bring about a positive or negative feedback. The big scientific
question, which we have been researching for more than a decade, is how do clouds respond to a change in CO2?
Advances in understanding will enable us to improve our confidence in climate projections.
5. Stratocumulus clouds reflect sunlight. There is now some consensus for reduced stratocumulus clouds in
a warming climate. Is this a positive or negative feedback? Explain.
6. High clouds, such as cirrus have a powerful effect as a blanket - helping retain heat radiating away from
the Earth's surface. The effect of a warming climate on cirrus clouds is currently being studied. What
would the effect of increases in cirrus clouds be? Would this be a positive or negative feedback?
Explain.
7. There are very large stores of methane locked away at depth in the ocean as methane hydrates. There's
some evidence to suggest that going back over a very long historical period (more than millions of
years), the release of these methane stores may have played a big role in abrupt and severe changes to
past climate. How close we are to any possible threshold is very much an open question.We know the
stability of these stores is dependent on temperature. As the oceans get warmer it's possible this balance
could be upset and the stores released. Would this be a positive or a negative feedback loop? Explain.
8. Permafrost methane is a big question mark but also potentially a very big deal. There are very organic
rich soils in certain parts of the world. At higher latitudes, these are frozen over by permafrost, and those
greenhouse gases are effectively locked away but could be released by rising temperatures. Would this
be a positive or a negative feedback loop? Explain.
9. Scientists have monitored the amount of methane, carbon dioxide, and other gasses released by thawing
permafrost and were able to link changes in the gas levels to the activities of soil bacteria. Specifically,
they found that methane spiked when melting began, but that it quickly dropped, apparently thanks to
methane-munching soil bacteria that absorbed the potent greenhouse gas. (Don’t celebrate yet, though—
those bacteria then excrete carbon dioxide, which, though 25 times less harmful as a greenhouse gas than
methane, is still not something we’d like more of in the atmosphere.) Is this a positive or negative
feedback loop? Explain.