IPCC AR5 summary

The IPCC’s AR5 summary is here, for those who want to actually read the details.

They look at four scenarios called RCP2.6, RCP4,5, RCP 6.0 and RCP 8.5. Basically the higher the number, the higher the level of greenhouse gas emissions over the next 85 years. The two middle scenarios are probably the most realistic as 2.6 assumes a very significant change in energy production and the like and 85 seems to assume no change at all. The scenarios are about more than just the level of emissions, so I am simplifying.

So what is the average temperature change projected under the two middle scenarios:

• RCP 4.5 – 1.4c by 2055 and 1.8c by 2090
• RCP 6.0 – 1.3c by 2055 and 2.2c by 2090

This is compared to 1986 – 2005.

And the sea level change:

• RCP 4.5 – 26cm by 2055 and 47 cm by 2090
• RCP 6.0 – 25cm by 2055 and 48 cm by 2090

The upper end of the worst case scenario (RCP 8.5) for sea level rise is 82 cm by 2090. That would post significant challenges for many countries – but is nothing like the nonsense some talk about of metres and metres of sea level rise.