Outline the processes by which a species may evolve a greater tolerance to higher temperatures.

Explain how the atmosphere plays a role in maintaining life-supporting temperatures over the Earth’s surface.

In addressing environmental issues, mitigation strategies may be seen as primarily ecocentric and adaptation strategies as primarily technocentric.

To what extent is this view valid in the context of named strategies for addressing the issue of global warming?

a species will contain a variety of different genotypes/characteristics / mutations will increase the variety of genes/characteristics;
some genes may provide greater tolerance to high temperature than others;
individuals with these genes are more likely to survive if high temperatures are limiting / there will be “survival of the fittest” / tolerant will outcompete intolerant;
these individuals will reproduce offspring with their tolerance/genetic characteristics / their characteristics are heritable/passed on to next generation;
natural selection will eliminate intolerant individuals/increase frequency of tolerant individuals;
over time/generations, tolerance may become a dominant characteristic in population;

If candidates mistakenly address process of speciation then just credit those aspects that are equally valid in microevolution, e.g. natural selection/survival of fittest/heritability, etc.

atmosphere allows solar energy/wide range of wavelengths to reach Earth’s surface;
water vapour/humidity/clouds absorb/reflect incoming IR/solar energy exerting a cooling effect;
greenhouse gases such as CO₂/methane/NO_x/tropospheric ozone/ CFC/HCFCs/water vapour;
absorb re-radiated heat/outgoing longer wavelength (Earth's) radiation;
this creates greenhouse effect that keeps planet warmer;
most heat is radiated to the equatorial/lower/tropical latitudes;
the tricellular model/convection currents/prevailing winds transfer this heat to higher latitudes;
maintaining a greater dispersal of life-supporting temperatures over planet;
heat at equator causes rapid evaporation;
…this water vapour carries latent heat that can be released on condensation/at higher latitudes;
tropical cyclones transfer large quantities of such heat to higher latitudes;
winds may contribute to oceanic currents transferring heat;

Credit should be awarded only for MPs that address role of atmosphere, not other influences on temperature.
Do not credit response that ozone hole leads to warming...unless it is qualified by being a relatively insignificant contribution.

Refer to paper 2 markbands, available under “your tests”  tab > supplemental materials.

The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.

Answers may include:

• understanding concepts and terminology of mitigation, adaptation, ecocentric/technocentric values, causes and impacts of global warming, strategies for reducing causes/managing impacts, carbon sinks, etc.;
• breadth in addressing and linking wide range of relevant strategies with mitigation or adaptation and with ecocentric values e.g. restraint/low consumption, changed lifestyles, sustainability, low technology, decentralization, and technocentric values e.g. maximizing growth, unlimited exploitation, resolving issues through technology, & scientific expertise, etc.;
• examples of mitigation improving energy efficiency/consumption, alternative energies, reduction of emissions, e.g. catalytic converters, geoengineering, fertilizing oceans, afforestation/forest protection, UNREDD, carbon capture and storage, nutrifying oceans, etc. and adaptation flood defence, desalinization, vaccination, crop choice, etc.;
• balanced analysis of the extent to which mitigation strategies are genuinely ecocentric and adaptation strategies are technocentric including counterarguments (may include reference to anthropocentric nature of some strategies) etc.;
• a conclusion that is consistent with, and supported by, analysis and examples given e.g. “although, in general terms, ecocentric values favour a preventative approach and living within the sustainable limits rather than adapting to human impacts, some mitigation strategies involve a heavy use of large scale technology, acceptable to technocentrics, but to which ecocentrics are generally opposed”; 

Many candidates were able to describe processes of natural selection and survival of the fittest, although some confused their response with references to speciation.

Few candidates scored well on this question primarily through confusing the role of the ozone layer with global warming. From a large sample of scripts, over 60 % of candidates were under the mistaken impression that 'the prime cause of global warming was the hole in the ozone layer that has been damaged by greenhouse gases like CO₂ and methane'! It is phenomenal how popular this mistaken myth predominates amongst the candidature. It was a minority that were able to think beyond the greenhouse effect and address reflection from clouds, convections cells and tropical cyclones spreading heat and latent heat over the Earth's surface. 

Generally, there were many good responses to this question. However, there was a tendency for error to creep in to the clear distinction between mitigation and adaptation. Strategies like carbon capture, renewable energies, afforestation were commonly and mistakenly addressed as adaptation strategies. The fact that adaptation strategies are those enabling us to live with the impacts of climate change rather than attempting to reverse them, was not clearly grasped by many candidates.