I often hear climate sceptics arguing on social media that CO2 is not responsible for climate change. Quite the opposite, CO2 is naturally needed for plant growth. Then concluding that climate scientists are wrong.
I must assume that all informed readers know the reality. But maybe not how to counter these arguments.
My usual answer to someone saying CO2 is good for plant growth:
“Too much is too much.” or
“If you drink too much alcohol you feel sick or could even die.”
More detailed I may explain it this way:
In a natural carbon cycle, carbon dioxide is re-absorbed by plants and trees. However, we are burning fuels so quickly that plants and trees that are alive have no chance of soaking it up (and cutting down rainforests worsens the situation). The effect of the extra carbon dioxide in the atmosphere is that the overall temperature of the planet is increasing (global warming). Whilst the average global temperature is increasing, on a day-to-day level the climate is changing in unpredictable ways (from floods and hurricanes to heat waves and droughts). To try and reduce the risk of ever more extreme weather, we need to reduce how much fossil fuel we are burning.
– Skeptical Science: “http://www.skepticalscience.com/co2-plant-food.htm”
– The Carbon Account: “http://www.thecarbonaccount.com/carbonexplained/”