More CO2 in the air means more risk of entirely new climates or climates disappearing

As Earth warms, predicted to happen by up to 15 degrees F (8 degrees C) at some latitudes before this century ends, climate zones are likely to shift away from the equator and toward the poles. Polar bears and ring seals, which depend on Arctic ice, will be threatened by this shifting. The change in temperature is likely to be greater in the Arctic and Antarctic because when snow and ice melt, their ability to reflect sunlight diminishes, thereby accelerating the warming effect (a worrisome positive feedback). In the tropics, normal fluctuations in temperature and rainfall are less, but small changes in temperature can make a big difference in these warmer latititudes as well, driving plant and animal species northward or to their extinction if they cannot migrate and adapt fast enough.

According to the press release by the National Science Foundation, severely affected parts of the world include the southeastern United States, southeastern Asia, parts of Africa, and biodiverse regions such as the Amazonian rainforest and African and South American mountain ranges.

Researchers from the University of Wisconsin-Madison and University of Wyoming conclude that

...the business-as-usual scenario comes with large climate changes the world over and would create entirely new patterns of temperature and precipitation for 12 to 39 percent of Earth's land area. An additional 10 to 48 percent of land would see its climate zones disappear, replaced by patterns of temperature and precipitation now occurring elsewhere, such as rain forest becoming savanna or evergreen forest becoming deciduous.

Above quoted from New 100-Year Forecast: Climate Zones Humans Have Never Seen at Scientific American.