geology-The units for the measurement

| March 14, 2016


Climate Change Activity ­ WebCOM™ 2.0

Stony Brook University Water, Climate & Energy

Please fill out the below form. Once you have answered all of the questions, click the ‘Submit’ button and a copy of your responses will be e­mailed
to you.
* In these questions you are asked to consider some possible future scenarios for atmospheric greenhouse gas accumulations. To start, go to and find the most recent monthly CO2 measurement. Round your answer to a whole number.

CO2: ____________ ppm

* The units for the measurement of CO2 in the atmosphere are ppm, or parts per million – this indicates the total amount of CO2 existing in the

This website also indicates CO2 levels for the last few years. Using past years of CO2 levels, find the yearly rate of increase for CO2 levels. In other
words, how much CO2 was emitted to the atmosphere in the past year? Round your answer to a whole number.

CO2 emissions: _____________ ppm/year

* Make sure you note the difference between the amount of CO2 in the atmosphere (ppm) and the emissions (amount added each year) of CO2 to the
atmosphere (ppm/year).

Now let’s consider some scenarios for the future. Right now, human population is just over 7 billion people. Those 7 billion people together are
producing the yearly emissions of CO2 which you specified above. If there are more people, more CO2 would be emitted to the atmosphere. What is
human population expected to be in 2050? (Use text or internet to find your answer.)

2050 human population: _____________ billions

* Now calculate how much CO2 that many people would emit each year, assuming no other changes.

2050 human population * 2015 emissions = 2050 emissions
2015 human population

CO2 emissions in 2050: ___________ ppm/year

* Of course, it’s unlikely that nothing else besides population would change. In recent years, for instance, a major global change has been the steadily
increasing number of people who are able to live the middle­class lifestyle and levels of consumption that are typical in the United States. Those
middle­class lifestyles and consumption levels are responsible for the bulk of CO2 emissions – people living at subsistence levels are contributing
negligible amounts of CO2 to the atmosphere. So let’s consider the additional change that would result from more people living life in the middle
class. Right now, about 2 billion of the world’s population is in the middle class – by 2050, about 4 billion people will live in middle class
circumstances and CO2 emissions should be expected to increase proportionally.

2050 middle class population * 2014 emissions = 2050 emissions
2014 middle class population

Middle­class CO2 emissions in 2050: __________ ppm/year

* Our goal now is to determine what CO2 levels should be expected by the year 2050, with the yearly emissions we have determined. An accurate
calculation should use calculus – but we will assume that the rate of increase is uniform, so that we can use the average emissions over the entire
period 2014­2050. Find the average of these two values, emissions today and expected middle­class emissions in 2050.

Average CO2 yearly emissions 2014 and in 2050: __________ ppm/year

* Now find the total amount of CO2 which will be added to the atmosphere between now and 2050, by multiplying average emissions by the number of

Total CO2 emissions in the period 2014­2050: __________ ppm

* Add that amount to the CO2 levels present in the atmosphere now.



Climate Change Activity ­ WebCOM™ 2.0

2050 atmospheric CO2 levels: __________ ppm

* (Your answer to the last question should be in the hundreds, not thousands or tens of thousands. If it is not in the hundreds, go back to your earlier
calculations to find your mistake.)

Now let’s consider a somewhat more optimistic scenario. Numerous changes to our energy infrastructure are being made, albeit slowly. If all coal­
burning power plants were converted to burning natural gas, electricity emissions would be approximately cut in half. If all vehicles were modified to
run off electricity or natural gas, transportation emissions could also be cut by about a third. Currently in the U.S., generation of electricity accounts
for 33% of CO2 emissions and transportation accounts for 28% of CO2 emissions. Assume that both generation of electricity and transportation were
to be completely converted to natural gas by 2050, and calculate the reduction in CO2 emissions which would result.

Reduction of electricity emissions would amount to a 17% reduction in total CO2 emissions, and reduction of transportation emissions would amount
to a 9% reduction in total CO2 emissions. Taking the two together would be an emissions reduction of 26%, or about one­fourth. We must also take
into consideration, however, the fact that changes cannot be made all at once. Assuming that it takes most of the time 2014­2050 to make these
changes, we can approximate their effect over the entire time by cutting the reduction in half. Find the reduced total CO2 emissions, using the total
emissions from above reduced by 1/8.

Reduced total CO2 emissions in the period 2014­2050: __________ ppm

* Add that reduced amount to the CO2 levels present in the atmosphere now.

Reduced 2050 atmospheric CO2 levels: __________ ppm


Now we have calculated a pessimistic and an optimistic estimate of how much CO2 might exist in Earth’s atmosphere in 2050. Keep in mind what CO2 levels to
compare that to: in the last million years, atmospheric CO2 has only ever fluctuated between 200 ppm and 300 ppm.

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