| Date | November 2018 | Marks available | 2 | Reference code | 18N.2.SL.TZ0.2 |
| Level | Standard Level | Paper | Paper 2 | Time zone | Time zone 0 |
| Command term | Identify | Question number | 2 | Adapted from | N/A |
Question
The hole in the ozone layer over Antarctica, discovered in the 1980s, was caused by chlorofluorocarbons (CFCs). The Montreal Protocol requires the use of hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (HFCs) instead of CFCs (Figure 3). However, these two gases are also linked to environmental problems (Figure 4).
Figure 3: Comparison of the effects of CFCs, HCFCs and HFCs
[Source: Avipsa Mahapatra, Climate Lead, Environmental Investigation Agency, Washington D.C.]
Figure 4: HCFCs and HFCs cause less damage than CFCs but still
affect the environment
[Source: © 2016 Cognitive www.wearecognitive.com / Children’s Investment Fund Foundation (CIFF) www.ciff.org]
Identify two possible consequences for life on Earth resulting from the depletion of stratospheric ozone.
Outline why the Montreal Protocol may be considered the world’s most successful environmental treaty.
Outline why governments agreed to phase out the use of HFCs from 2019 in the Kigali Amendment to the Montreal Protocol.
Identify one advantage of staggered dates for the phasing out of HFCs for countries at different levels of economic development.
Identify one disadvantage of staggered dates for the phasing out of HFCs for countries at different levels of economic development.
Markscheme
increased skin cancer/melanomas/skin aging/mutations;
increased eye abnormalities/cataract/photo allergy/blindness;
weakening of immune systems;
disrupts plant growth / damage leaves thus reducing photosynthesis / loss of plant species;
damage to phytoplankton in oceans / reducing base of food web;
causes death of krill/zooplankton/amphibian larvae reducing diversity/food for higher trophic levels.
Note: Do not give credit for responses simply stating it leads to increased UV (Q asks for impact on “life”). Do not credit responses identifying consequences linked to GW. (Increased UV has negligible DIRECT impact on GW however, INDIRECTLY, eg by reducing primary productivity, it may contribute to GW, but such an indirect link would need to be explicitly stated to gain credit).
clear evidence of successful reduction in CFC use/ozone depletion/size of ozone hole;
protocol prompted production of alternatives to replace CFCs allowing smooth phase-out;
financial assistance was offered to assist in phase out of CFCs (Multilateral Fund);
demonstrated it was possible for governments to work multilaterally;
led to changes in the behaviour of individuals and societies;
very large number of signatories;
secured binding environmental agreements/legal commitments with which countries/industries complied;
there was a widespread/common acceptance/understanding of the effect of CFCs (amongst scientists/public/politicians).
Note: Simply stating “CFCs were banned” or “banning of CFCs” is not sufficient for credit.
because HFCs are bad for climate/contribute to global warming;
realisation that environmental issues need to be addressed at an intergovernmental level;
realisation that changes in behaviour are necessary to protect the environment in the future;
in response to development in scientific understanding of issue;
rich countries agreed to provide financial assistance for poorer countries to phase out HFCs;
because technological development has found alternatives to HFCs.
allows less developed countries more time to raise necessary funding;
allows less developed countries time to develop/import necessary technology/infrastructure;
allows less developed countries time to introduce significant changes in policy/governance;
deadlines are more reasonable so more countries are likely to commit to change;
issue can start being addressed sooner by more developed countries.
may prolong achievement of complete/global phasing out;
may reduce action to a lower priority than necessary in some countries;
may prompt some multinational companies to relocate to countries with later deadlines;
developed countries, given shorter deadlines, may be more dependent on HFCs so have more to do;
countries avoiding early phase out may benefit from production/trade of HFCs;
cost of early change/application of untested substitutes may lead to conflict from more developed countries;
conflicts arising from different treatments between countries may undermine overall agreement.
Examiners report
Although many were able to identify impact of ozone depletion on human skin, probably a good half of the candidates were still perpetuating the erroneous myth that ozone depletion contributes significantly to global warming.
Well answered by the great majority, though many failed to seek out a second point to gain the full two marks.
Although the Kigali agreement is not specified in the syllabus, candidates only needed to apply what they knew to the new information presented in this question. Testing such ability to apply their knowledge in new contexts is an important aspect of this component of the exam and, for the most part, candidates did well.
These questions proved challenging for many candidates involving a degree of analytical thought and processing.
These questions proved challenging for many candidates involving a degree of analytical thought and processing.
