1. In your own words, define temperature anomaly (if you want a quick tutorial on
temperature anomalies and why they are useful, see this blogLinks to an external site. or
visit this web siteLinks to an external site.).
A temperature anomaly is when the temperature differs from the long-term average temperature
or baseline temperature. Temperature anomalies can be used to indicate global temperature or the
temperature of certain regions of the globe. They are a good tool to show the change in
temperature of a given region from year to year compared to a baseline. Anomalies do a better
job showing climate variability than average temperature because temperature can vary much
more than temperature anomalies do and it is easier to compare anomalies to each other than
average temperatures.
2. Using Excel (or similar program, such as Numbers for Mac) graph columns A-D, using
years as X axis and temperature anomaly as Y axis. (It is probably best to use either a line
or stacked area chart for this; if you need help with Excel you can view the vid eo tutorial
above or go to this link,Links to an external site. or for Numbers, go to this linkLinks to
an external site..) In your own words, describe the resulting graph. What stands out? Are
the temperatures for different zones of the globe changing at the same rate? Have they
changed the same way through time?
The main thing that I notice is how the temperature anomalies for the globe, northern
hemisphere, and southern hemisphere have a positive trend over time. Closer to 1880 there are
almost all negative temperature anomalies whereas in the late 1930’s and into the 1940’s is when
positive temperature anomalies become a lot more frequent, and the number of negative
anomalies start to decrease. After 1976 there are no more negative temperature anomalies. In
fact, there are only positive temperature anomalies after 1976 with the one exception being the
northern hemisphere being at 0 in 1985. From 1880 to 1996 the temperatures tend to be moving
together. There is some variance, but one is clearly not increasing at a faster rate than another.
Starting in 1997 the northern hemisphere starts increasing much more significantly than the
southern hemisphere while the increase in the temperature of the globe sits roughly in the middle
of the two hemispheres. This shows that the northern hemisphere’s temperature is increasing at a
faster rate than the southern hemisphere. The northern hemisphere also experiences more
variability from year to year in terms of temperature anomalies.
3. Using Excel or Numbers, and the same data set, make a simple line graph and compare
column H (64-90° N) and J (24-44° N) (as Y axis) by year (X axis). What are a couple of
differences you see, or what stands out to you when you look at this graph? Do the lines
have the same shape? From these data, what generalization(s) can you make about how
the 64-90° N data behave relative to the data from 24-44° N?
A big difference that stands out between the two is the variability of the anomalies from year to
year. In the 64-90N data set the temperature anomalies vary a lot more from year to year than in
the 24-44N data set. At the start, the 64-90N data set experiences greater negative temperature
anomalies than the 24-44N data set. Over time both data sets are increasing but the 64-90N data
set is increasing at a higher rate than the 24-44N data set. Just as the 64-90N data set experienced
greater negative temperature anomalies at the end of the 1800’s it experiences grater positive
temperature anomalies specifically in the 1920s-1950s and in the 2000s than the 24-44N data set.
The two lines have the same positive trend upwards but the 64-90N line is much more volatile
than the 24-44N line. From the graph it can be concluded that the 64-90N region of the world is
warming at a more rapid rate than the 24-44N region of the world in recent years. Global
warming has affected the northern region of the hemisphere more than the middle latitudes. It
can also be concluded that the 64-90N region is more susceptible to changes in the climate
because of how the temperature anomalies can vary so much in the positive and negative
directions from year to year whereas the 24-44N region has a more stable climate.
4. Compare column H (64-90° N) to column O (64-90° S) to look at the differences between
far northern (Arctic) and far southern latitudes (Antarctic). Is the Arctic warming at the
same rate as the Antarctic?
In 1880, the Antarctic was warmer than the Arctic. In the following 20-30 years the Arctic
warmed while the Antarctic cooled. Since the start of the 2000s the Artic has warmed at a much
higher rate than the Antarctic. Between 1910 and 1960 the Antarctic experienced much more
variability in temperature anomalies than the Arctic. The Antarctic was also generally cooler
than the Arctic at this time with a couple years that were close in terms of temperature
anomalies. Recently, the Artic has been experiencing temperature anomalies over plus 2 whereas
the Antarctic has only experienced 3 temperature anomalies over plus 1 since the Artic has
started experiencing those consistent plus 2 anomalies. This clearly shows that the Artic is
warming at a much higher rate than the Antarctic. The increase in global climate has had a
greater effect of the Artic as shown by the higher temperature anomalies.
5. Based on your analysis of these data, what are some of the possible reasons to explain the
differences between the temperature trends: a) between the northern and southern
hemisphere; b) between the Arctic and farther south in the northern hemisphere (24-44°
N); and c) between the Arctic and Antarctic? Please identify one feedback mechanism
that may account for some of the differences we see between the Arctic and other
locations.
The data shows that the Northern Hemisphere is warming at a faster rate than the
Southern Hemisphere. A major reason for this is because the Northern Hemisphere has much
more land than the Southern Hemisphere. Land heats faster than the ocean (it also cools faster
than the ocean) so it is reasonable to think that an increase in global temperature would heat the
part of the earth with more land faster than the part of the earth with more water. This also works
in the opposite direction and is shown in the graph. In cooler years the Northern Hemisphere
cools more than the Southern Hemisphere relative to the previous year. This shows how the
Northern Hemisphere is overall more susceptible to climate change than the Southern
Hemisphere and why, at this moment, it is warming at a faster rate than the Southern
Hemisphere.
The Arctic is warming faster than lower Northern Hemisphere latitudes because the
Arctic is relatively cooler to begin with than the lower latitudes. This means that an increase in
global temperatures will have more of a warming effect on the Arctic. Think about it this way, a
1-degree Celsius increase in temperature when it is warm out does not make that much of a
noticeable difference. When that 1-degree increase pushes something from below freezing to
above freezing, there is a much bigger impact on it. This is part of the reason the Arctic has
warmed faster than lower latitudes. The Arctic is mostly made up of sea ice which has an
extremely high albedo effect. Most of the sunlight that hits the Arctic is reflected by that sea ice
and not absorbed thus not making a huge difference in terms of warming. Over the past couple of
years, however, a positive feedback loop has been created in the warming of the Arctic. As the
oceans become warmer sea ice starts to melt. As sea ice starts to melt the albedo effect of the
Arctic decreases and more sunlight is absorbed. As more sunlight is absorbed the ocean becomes
warmer. As the ocean becomes warmer, more sea ice melts and the cycle repeats. A big way in
which the Arctic would stay cool is by that albedo effect. As the albedo effect decreases with sea
ice loss the Arctic warms. Lower latitudes do not have as high of an albedo effect so they are
already absorbing more energy than the Arctic was and so they are not experiencing as rapid of
an increase in energy absorption as the Arctic. They were already absorbing more of the
available energy.
The Arctic is made up of mostly sea ice whereas the Antarctic has a lot of land ice.
Generally speaking, sea ice melts faster than land ice. This can be a factor as to why the Arctic is
warming faster than the Antarctic. The Antarctic has not lost as much ice as the Arctic and
therefore has maintained a higher albedo effect. While the Arctic is stuck in a positive feedback
loop that rapidly increases its temperature the Antarctic is not experiencing the same feedback
loop and thus is not as impacted by the increase in global temperature. Despite land warming
faster than the ocean, the land covered by the ice in the Antarctic is not exposed to the sun.
Therefore, the land cannot warm at nearly the same rate as the Arctic Ocean. The Arctic Ocean is
actively absorbing sunlight and melting the ice that covers it whereas the land of the Antarctic
cannot do that to the same effect.