Modern temperatures, sea levels, and extreme weather events are neither unusual nor unprecedented. Many regions of the Earth are cooler now than they have been for most of the last 10,000 years.
Natural factors such as the Sun (106 papers), multi-decadal oceanic-atmospheric oscillations such as the NAO, AMO/PDO, ENSO (37 papers), decadal-scale cloud cover variations, and internal variability in general have exerted a significant influence on weather and climate changes during both the past and present. Detecting a clear anthropogenic forcing signal amidst the noise of unforced natural variability may therefore be difficult.
And current emissions-mitigation policies, especially related to the advocacy for renewables, are often costly, ineffective, and perhaps even harmful to the environment. On the other hand, elevated CO2 and a warmer climate provide unheralded benefits to the biosphere (i.e., a greener planet and enhanced crop yields).