Question 23M.2.SL.TZ1.1c
| Date | May 2023 | Marks available | [Maximum mark: 2] | Reference code | 23M.2.SL.TZ1.1c |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Analyse | Question number | c | Adapted from | N/A |
There is evidence of a change in mean LAI values on Earth over recent decades. Changes can be quantified by calculating LAI anomalies. These are differences between annual LAI values and the mean LAI for the entire given time period.
The graph shows global LAI anomalies for the period from 1981 to 2014, based on data from GIMMS. It also shows mean global LAI anomalies between 1981 and 2009, based on data from three other remote sensing programmes. Vertical bars show the timing of El Niño events. The darkness of the bars indicates the intensity of the El Niño events. The darker the bar, the more intense the event.
[Source: Material from: Zhu, Z., Piao, S., Myneni, R., et al., Greening of the Earth and its
drivers, published 2016, Nature Climate Change, reproduced with permission of SNCSC.]
Analyse the data shown in the graph for evidence of a relationship between LAI and El Niño events.
[2]
- decreases in LAI during El Niño
OR
increases in LAI between El Niño events; - 1983-4/other example of a decrease during El Niño
OR
1984-6/other example of increase between El Niño events;
OR
94-95/2009 anomalous as LAI rises during El Niño event;
OR
99-2000 anomalous as LAI decreases between El Niño events; - larger decrease (in LAI) with more intense/longer El Niño events
OR
no/less decrease during less intense/briefer El Niño events;
Mpa refers to changes in LAI, not whether levels were high or low.
The example given for mpb must correspond with the trend given in mpa. The graph does not show the years clearly so we must show some lenience in mpb – award this mark if it is clear which period the candidate was referring to.
For mpa, do not accept answers implying that decreases in LAI cause El Niño or increases in LAI prevent El Niño.
