Turn over 3 2 (a) Table 1 below shows the area of the northern hemisphere covered by either snow or ice in January and July for selected years between 1970 and 2020. Year Area in million km2 January Rank Order Area in million km2 July Rank Order d d2 1970 48.26 3 4.94 2= 0.5 0.25 1975 44.95 11 4.60 4 7 49 1980 45.91 9 5.40 1 8 64 1985 50.18 1 4.94 2= –1.5 2.25 1990 45.67 10 2.97 8 2 4 1995 46.13 8 3.97 5 3 9 2000 47.61 4 3.55 6= –2.5 6.25 2005 46.56 6 3.55 6= –0.5 2010 48.84 2 2.51 10 –8 64 2015 47.15 5 2.52 9 –4 16 2020 46.36 7 2.41 11 –4 16 Σd2= Table 1 Complete Table 1 by calculating the value of d2 for the year 2005 and then calculating the value of Σd2 (2) Using the formula below, now calculate Rs. Rs 1 6 2 3 d n n Give your answer to two decimal places. You must show your working. (2) Rs = .............................................................. 4 (b) Explain why the data used in Table 1 might not be a reliable guide to the impact of global warming on snow and ice coverage. (4) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 2 = 8 marks)