There are winners and losers, with most the world's population being losers, but for us here in the Northwest the changes will be favorable, with substantially more mild days, particularly in the spring and fall.
Before giving you the results, a few details. The definition of mild weather in this paper is:
- Daily maximum air temperature between 18 and 30 °C (64 to 86F).
- Daily total precipitation not exceeding 1 mm (.04 inches). This is not much.
- Daily mean dew point temperature not exceeding 20 °C (68F). High dew point are associated with sticky, humid conditions.
(If I was going the study, I would have had mild temperature ranging from 60 to 80F, precipitation not exceeding 2 mm, and dew point not exceeding 15°C, reflecting my Northwest U.S. tastes.)
The following plots show the changes in the probability of mild days from now to 2081-2100) for each month, with blue indicating more mild days, and orange denoting fewer mild days. In places with a warm climate (e.g., Miami), the changes are not good. There are no mild days during summer in Miami. Quite frankly, temperatures changes is the least of Miami's global warming problems--rising sea level will probably flood the place.
Los Angeles and Denver, with cooler climates than Miami, will see improvement during winter and the adjacent months, with serious degradations during the warm months. Same thing for Chicago and New York City.
But Seattle is different. We are real winners. There will be substantial increases in the number of mild days from June to October, while the loss of mild days in mid-summer are relatively small. But it is really better than that. None of our winter days will be in the mild category (64 to 86F), but they will be considerably more pleasant than today (46 feels a lot warmer than 39F) .
And did you note the percentage of mild summer days in Seattle has been and will be around 70%...higher than almost any place else in the country any time of the year? Only LA in November and May are as good. And who would want to live in LA, anyway?
The Climate Change paper also took a global view, as shown in the figure below. Folks living in locations that are relative warm in summer (tropics, subtropics, India, SE Asia, SE U.S., China) will be losers. That includes most of the Earth's population. In contrast, Canada, Russian, the NW U.S., southeast Australia, lower South America, and northern Europe will be winners--more mild days. Canada does particularly well. Africa will be hit hard as will Brazil.
Western Washington and Oregon will relatively favored (at least in temperature) by global warming because we start off on the cool side, with warm extremes reduced by the cool eastern Pacific. The warmer the land gets in summer, the more onshore (cool) flow develops--our natural air conditioning. And offshore (downslope) flow over the Cascades is predicted to decrease with global warming.
But although our temperatures will get progressively more pleasant during this century, other changes will not be as favorable, such as more extreme rainfall in winter, reduced snowpack, and worsened flooding in the fall. So lessening the increase in greenhouse gases would certainly be in our own best interests. You can always put on a sweater.