IB ESS SL 6.4 Stratospheric Ozone Question Bank

ozone initially declined;
b. ozone stabilized / began to increase slightly;

Note: do not credit descriptions of the projected values

Allow 1 mark for overall decline
Precise dates are not necessary for credit (i.e. accept change occurring around 2000).

halons/CFCs/HCFCsHBFCs/ $\mathrm{N}_{2} \mathrm{O}$ /methyl bromide/methyl chloroform/carbon tetrachloride/ chlorine/bromine:

Note: do not credit HFCs/ODSs

a. cell damage on leaves / reduced leaf size/reduced plant growth/ photosynthesis;
b. reduced phytoplankton in oceans;
(d) Identify the year that stratospheric ozone is predicted to return to 1980 levels in the stratospheric-ozone chart shown above. [1]

Accept any year in range 2041-2043;

a. Montreal Protocol resulted in unprecedented international cooperation to address loss of ozone (and its influence still continues);
b. banned use of CFCs/ phasing out of CFCs/ ozone depleting substances /refrigerants/aerosols/recycling of refrigerants;
c. alternatives to CFCs (HFCs/HCFCs) were developed reducing harm to ozone;
d. education/awareness campaigns led to changes in consumer preferences;
e. ozone reforms due to natural reversible chemical reactions/processes / ODSs eventually begin to break down/dissipate;