17. Allergy season has lengthened
Pollen season in the United States started three days earlier on average between 2001 and 2010 compared to the 1990s.
18. More heat waves
The total global land area that has 30 days of extreme heat per year has roughly doubled since 1998.
19. Increasing drought
If the increase in global average surface temperature reaches the 1.5°C mark, which it is almost certain to do, 350 million additional people will be exposed to severe drought regularly.
20. More global precipitation
More water vapor in the atmosphere as a result of global warming has led to an 8.5% increase in annual daily precipitation worldwide since 1900.
21. More precipitation in the US
Annual precipitation in the United States has increased by approximately 4% between 1901 and 2015.
