Under a business-as-usual, high-emissions scenario (RCP8.5 in the models used by the Intergovernmental Panel on Climate Change), the Southwest will be about 4.5°C (8°F) warmer in the second half of the century compared to the second half of the 20th century, climate models show. Megadroughts will become very likely by the end of the century, above 90 percent probability with no change in precipitation, the study found. Even a 30 percent increase in precipitation would not be enough to overcome the effects of higher temperatures.
If the world instead cuts its emissions to levels close to those agreed to by international leaders at the Paris climate talks last December, meeting the IPCC's RCP2.6 trajectory, the Southwest will be about 1.9°C (3.4°F) warmer in the second half of the century compared to the second half of the 20th century. Megadroughts will still be more likely than today, but the probability is less than 66 percent with no change in precipitation, falling below 50 percent with a modest increase in rainfall, the study found.
If the temperature increase is held to 1°C, the megadrought risk across most of the region falls to 20 percent with no change in precipitation, the study says.
Even with international protections, the Galápagos Islands are becoming more vulnerable to humans