IS Unit 7: Environmental Issues NAME
EXAMINING TRENDS IN CO2LEVELS & TEMPERATURE PER. Date________
Carbon dioxide (CO2) is the primary greenhouse gas. It is produced when humans burn carbon-
based fuels such as wood and bio-mass, but the majority of what humans burn are fossil fuels
(oil, gas, and coal) to heat their homes, make electricity and drive cars. Plants and trees absorb
CO2 for photosynthesis and release oxygen. As forests have been cut down around the world
more carbon dioxide has been released into the atmosphere and the CO2 that is in the
atmosphere is staying there because there are fewer trees to absorb it and convert it to oxygen.
According to the International Panel on Climate Change (IPCC) As a result of human activity
there is about 25% more carbon dioxide in the atmosphere today than there was 100 years ago.
The "greenhouse effect" occurs when greenhouse gases (CO2, methane, water vapor and CFC's)
absorb heat from the Sun that is being radiated from the Earth into space. Scientists predict that
doubling the pre-industrial (1850) level of CO2 in the atmosphere would increase average global
temperatures by 2.8 o C. The greatest temperature increases would occur in the Northern
Hemisphere above 40o latitude, where the burning of fossil fuels and seasonal changes in plant
growth are the greatest. Predictions are that above a line which runs through Northern California,
Denver, Indianapolis, and Philadelphia, droughts would be common, and many fertile food-
producing areas would turn to dust bowls.
The CO2 level data presented in the table below shows average CO2 levels collected at the
Mauna Loa Observatory in Hawaii and at the McMurdo Research Station on the South Pole,
where the air is well mixed, far from local CO2 sources. The average global temperature is
compiled from data gathered by the National Oceanic and Atmospheric Administration, which is a
United States government funded research laboratory.
TABLE 1: Year, Average Global CO2, Average Global Temperature
Average Avg. Global
YEAR Global CO2 Temperature
1850 265 13.6
1870 291 13.8
1900 287 13.6
1920 303 13.6
1930 310 13.8
1960 317 13.9
1965 320 14.0
1970 325 14.0
1975 329 14.1
1980 337 14.1
1985 345 14.1
1990 352 14.2
1995 359 14.3
2000 370 14.4
1. Plot the data found in the table above on the graph paper provided. Prepare your
horizontal axis to include years 1850 to 2050. The vertical axis will represent CO2 levels
from 250 to 450 ppm. Plot the appropriate points, and draw a smooth curve representing
the trend of the plotted points. (Do not draw a straight line or attempt to connect every
point. A smooth curve shows general trends.)
2. Assuming that the trend in your smooth curve continues from 1985 to 2050, extend your
curve with a dashed line to the year 2050. Do this by extending the already plotted line
with a ruler. This line is a prediction for the future based on past trends.
3. Give your graph an appropriate title; be sure to label the x- and y-axis and include the
1. How is CO2 produced by humans? (See introduction)
2. What is the "greenhouse effect"? (See introduction)
3. What does your graph indicate about the general change in CO2 levels since 1870?
4. Using the dotted line that is on your graph, predict the CO2 levels for the following years.
5. Which prediction in the previous question is the most accurate? Why?