A、Exhaust emissions from cars and other vehicles. B、The increasing population and the decreasing green vegetation. C、The chemica

(19)The World Meteorological Organization reports the level of carbon dioxide emissions in the atmosphere has reached a record high this year, driven in part by the powerful El Nino event, which started in 2015 and continued well into 2016.
    According to WMO, the concentration of carbon dioxide in the atmosphere reached 400 parts per million for the first time in 2015 and surged to new records this year.
    WMO Secretary General, Petteri Taalas says this symbolic, but significant milestone bodes ill for the planet as these CO₂ emissions will stay in the atmosphere for generations.
    "At the moment, we are not moving in the right direction. We are actually moving in the wrong direction and this warming potential of the planet has been growing," Taalas said.
     (20)Carbon dioxide results from the burning of fossil fuels and other human activity. Meteorologists say CO₂ accounts for 65 percent of the warming effect on our climate.
    Two other greenhouse gases, methane and nitrous oxide contribute about 17 percent and six percent respectively to the long-lived warming of earth’s climate.
     (21)Taalas says it is not possible to tackle climate change without tackling CO₂ emissions because the lifetime of this greenhouse gas is very long.
    "There have been some scientific studies estimating that the return back to pre-industrial levels may take tens of thousands of years. And, therefore, it is really urgent that we start reducing the emissions of carbon dioxide and if we do not do so, then this problem will remain with us for thousands, even tens of thousands of years," Taalas said.
    Taalas welcomes the Paris Climate agreement. But, he notes its impact may be limited as emissions reductions are voluntary and not legally binding.(22)He says the world still has a chance to turn things around in the coming decades if it moves from political will to concrete action.
    He says negative trends will continue for several decades. But, he adds improvements in the climate will be seen by 2060 if nations start reducing their CO₂ emissions now.
Questions 19 to 22 are based on the recording you have just heard.
19. What is the talk mainly about?
20. According to the talk, what does carbon dioxide result from?
21. Why is it impossible to tackle climate change without tackling CO₂ emissions?
22. What does Taalas say about the climate?