Richard: “…it is not “disingenuous” to choose 1998 as the year when the last period of warming stopped.”
Yes it is, because if you had chosen 1997 or 1999 you could not claim that global warming had “stopped”. Fact is, on a global scale the decade from 1998 has been around 0.8 deg C warmer on average than the first decade of the 20th century. In other words, the long-term trend is upwards.
Levels of CO2 in the atmosphere have increased by at least 30 percent over the past 200 years, almost all due to human activities. CO2 has the effect of retaining heat in the atmosphere, hence the warming.
On a geological scale, this is very fast warming. A warming gas is unstable, hence the concern over the long-term effects. The safest and most effective way of mitigating the warming is to reduce emissions of CO2.
