Final answer:
Greta Thunberg's rhetorical question in her speech emphasizes the current CO2 emission reduction efforts as ineffective and calls for immediate and radical action rather than complacency with 'business as usual.'
Step-by-step explanation:
The underlined rhetorical question in Greta Thunberg's speech, "How dare you pretend that this can be solved with just 'business as usual' and some technical solutions?" is posed to challenge and criticize the current efforts in reducing CO2 emissions as being ineffective. This question emphasizes that the measures taken by the audience, presumably policymakers and leaders, are insufficient in addressing the severity of the climate crisis. It reinforces the urgency of the situation and implies that the current trajectory of CO2 emissions and reliance on modest measures will not prevent the grave consequences of climate change. By questioning the complacency surrounding 'business as usual,' Thunberg is asserting that radical action and sincere commitment to reducing emissions are needed immediately, reflecting the ineffectiveness of current efforts and the need for drastic change.