5000 4000 3000 thlutfaloustil nya papalitan Lowlane -4000 -5000 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 South Cascasde Sarennes Echaurren Norte 330 Figure 18.3: Glacier Mass Balance Data." 4. Refer to Figure 18.3. a. What is the overall trend in the mass balance data for the three glaciers? b. Use Your Critical Thinking Skills: When looking at mass balance data, why would it be important to analyze data over a long time span? 5000 4000 3000 thlutfaloustil nya papalitan Lowlane -4000 -5000 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 South Cascasde Sarennes Echaurren Norte 330 Figure 18.3: Glacier Mass Balance Data." 4. Refer to Figure 18.3. a. What is the overall trend in the mass balance data for the three glaciers? b. Use Your Critical Thinking Skills: When looking at mass balance data, why would it be important to analyze data over a long time span