Under the Business-as-usual scenario (RCP 8.5) the future climates in 2030 will most closely resemble Mid-Pliocene climates, with surface temperatures 1.8 °C to 3.6 °C warmer than preindustrial temperatures. This means a climate that resembles the climate 3-3.3 million years ago, when CO2 -levels were at 400ppm – levels which we have crossed in 2016. Mid-Pliocene conditions will first emerge in continental interiors and in the decades afterward they will spread towards the coasts.
In 2100 the situation will be totally different. Under the RCP8.5 scenario, the climate from the past that best matches continental interiors by 2100 is the early Eocene climate. For these climate conditions, we have to go back abut 50 million years, when global mean annual surface temperatures were a whopping 13 °C ± 2.6 °C higher than preindustrial temperatures and there were swampy forests in the arctic.
Under the RCP4.5 emission scenario the climate stabilizes at mid Pliocene-like conditions.