Short Answer 
The key questions to understand the GHG emissions graph are what caused the drop in emissions in 2009 and which industries were included in the study. Analyzing the reasons for the decline and identifying contributing sectors will be vital for guiding future emission reduction efforts and improving the study’s accuracy.
Identify Relevant Questions
To gain a comprehensive understanding of the data presented in the graph on Greenhouse Gas (GHG) emissions, we need to focus on two specific questions. These are:
- What caused a drop in GHG emissions in 2009?
- Which type of industries were included in the study?
Analyze Historical Emission Changes
Understanding the factors behind the drop in GHG emissions in 2009 is crucial. By investigating this decline, we can explore significant events or changes in policies that led to reduced emissions. This insight can help inform future actions aimed at lowering emissions effectively.
Examine Industry Involvement
It is equally important to identify the types of industries included in the study. Knowing which sectors contribute most to GHG emissions can guide regulatory efforts and public awareness campaigns. Additionally, this information can highlight other significant industries that may need to be addressed to enhance the accuracy of the study.