The 2011 Texas heatwave is thought to be 20 times more likely in a La Nina year than it would have been 50 years agoIt’s important to note that we don’t see evidence for a strong human influence in all weather extremes. In the example of the 2011 Thailand floods no discernable impact from human activity is found.
The Representative Concentration Pathways (RCPs) define feasible future emissions and forcings pathways, of varying severity, of greenhouse gas concentrations and aerosol emissions up to 2100. RCP8.5 is a high emissions scenario that can be considered a high fossil fuel “business as usual” future. RCP2.6, which can be considered a world with a transition to a low carbon economy, represents very strong mitigation. They, along with intermediary RCP4.5 and RCP6.0 will form the emissions input for the IPCC Fifth Assessment Report (see Figure top).