Estimate the volume of ice lost between 1850 and 1950.

State the year when the glacier began a continuous decline lasting to 2010.

Suggest why a short-term increase in glacial ice (positive balance) begins around 1950.

Distinguish between aridity and infertility in hot, arid areas.

Examine the causes and consequences of the melting of permafrost.

Accept answers in the range 21–22 metres water equivalent [1].

1970 [1] (accept 1969–1971).

Award [1] for stating that the accumulation of ice was greater than the melting of ice.

Award the second mark for one of the following:

Decrease in temperature leads to less melting [1] / Increase in snowfall leads to greater accumulation of ice [1] / other valid suggestion.

Soil aridity is the deficiency of moisture in the soil. Soil is considered arid if the rate of evapotranspiration in the soil is higher than the amount of water absorbed by the soil.

Accept climatic aridity as an alternative to soil aridity.

Infertility is a lack of necessary requirements for healthy plant growth (minerals, nutrients). It does not mean soils are unsuitable for plant growth, but the only plants that can grow are those that either need few nutrients or obtain them from fertilizers.

For example:

Aridity:
Is the lack of moisture/water in the soil [1] where evapotranspiration is greater than water provided [1], which limits the plants able to grow [1].
or
Aridity is a deficiency of moisture / an area with less than 250 mm/year [1], resulting from a permanent absence of rainfall / when evaporation exceeds rainfall [1], which limits plants’ ability to grow resulting in scant vegetation [1].

Answers may refer to an aridity index.

Soil infertility:
Is the lack of nutrients in an arid soil [1] but some plants can grow due to special adaptions to the conditions [1] or by the provision of fertilizers [1].

Award up to [5] for description/explanation of aridity and infertility with a maximum of [4] if only one term is considered.

Reserve [1] for the idea that the two can be linked or an attempt to distinguish, for example, not all soils in arid environments lack the necessary nutrients to be productive but the lack of available water limits plant growth and agricultural potential.

Possible causes include:

• annual seasonal melting and refreezing of the active layer
• potential impact of global climate change in extreme environments and possible feedback mechanisms
• melting resulting from resource development, settlement and communications.

Possible consequences include:

• implications for settlement and communications and mineral extraction, for example, subsidence, increased frost heave
• long-term implications of climate change for indigenous populations, for example, disruption of traditional seasonal migration routes
• possible costs/benefits for tourism depending on context, for example, possible safety issues for ski infrastructure.

Good answers may examine different timescales or different stakeholders affected by permafrost melting. Another approach might be to provide a structured examination of different consequences (positive/negative), a recognition of feedback mechanisms and also the interaction of natural and human causes depending on the location.

At band D, expect some description of the causes and consequences of permafrost melting. Do not expect balance.

At band E, expect either more detailed explanation of the causes and consequences of permafrost melting or a structured examination of the statement including a recognition that there are multiple causes which are place/time dependent.

At band F, expect both of these elements.

Marks should be allocated according to the markbands.