The National Climate Assessment, an impressive report released this month by 13 federal agencies and the White House, showed that climate change is already having devastating effects on our health and our economy and that the cost is hundreds of billions Dollar could increase the end of the century.
The report describes what we can expect if we aggressively cut greenhouse gas emissions now and what happens if we do nothing. As part of our Weather 2050 project, we have used the latter scenario to investigate what can happen to mid-century temperature and precipitation in US cities.
We've found that many US cities can see hotter, more southern parts of the country by 2050. Here are some of the most striking transitions:
As you can see on this map, climate change means that cities can move farther south in terms of temperature and precipitation patterns. In some cases, the closest match may be hundreds of miles away. If you want to get an idea of what climate change could mean to your city, you may need to take a trip.
By 2050, the average summer high in Cleveland, Ohio, will warm by 5.4 ° F. The average winter low rises 5.3 ° F. That means Cleveland will have the climate of a suburb of St. Louis more than 500 miles away.
Let us explain in more detail how the climate in different regions could change. Take a look at this animation of change in the Northeastern US:
You see that Scranton, Pennsylvania, will have a climate that today resembles that of Round Hill, Virginia. This is a distance of about 220 miles (as the crow flies), but this means that Scranton expects average summer peaks that are 4.8 ° F higher and the winter temperature 5.5 ° F higher.
We can also see that in the southeastern United States:
The cities in the south are moving even further south. By 2050, annual temperature and precipitation patterns in Atlanta, Georgia, will look more like Selmont, Alabama today. This is a movement of more than 200 miles, with the average summer high rising 4.1 ° F to 92.6 ° F.
Other parts of the country may have minor shifts until 2050, as you can see on this map of the Southwest:  Apache Junction, Arizona, is likely to experience a year-round climate more like Peoria, Arizona, a city which is only 80 km to the west. However, this still means that the average summer high of today, 103.5 ° F, will increase by 4.9 ° F by 2050.
What Climate Change Meant to the United States
For any given city there are some degrees of heat and more a few extra or less inches of rain over a season does not seem like much. But it can be the difference between enough rain for a healthy harvest and a drought that kills them. It's the difference between a wet winter and a white winter.
Not every part of the country changes at the same speed. In general, the northern parts of the US are warming faster than the southern ones, so climate change tends to be greater. Cities in the eastern United States and upper Midwest are likely to experience greater change than in the West.
However, it is clear that hundreds of cities have to adapt to changes that could be fundamental to people's lifestyles. More houses will need air conditioning as the summers are filled with deadly heat waves. More vegetation will dry out, causing more forest fire. This, in turn, could affect the local economy as climate-related industries such as agriculture or outdoor tourism decline.
It is important to know that the averages we quote do not tell the whole story. Some of the more temperate areas of the US, such as the California coast, will experience greater fluctuations in their weather. Rather than spreading rainfall all year round, periods of intense rain are expected in California, followed by extreme drought, a phenomenon described by researchers as a weather forecast.
The planet as a whole has been warming by 1 ° C since the beginning of the Industrial Revolution, and we are currently well on the way to seeing 2 ° C warming by 2040. But we still have the opportunity to prevent this from worst-case scenarios. And we already know what to focus on. Here are 10 ways to accelerate progress against climate change and a simple guide to working climate policy.
How We Made These Maps
We generated our city pairs by adjusting future annual temperature and precipitation forecasts. Today's climate patterns are year round in search of present and future cities, the most closely connected are.
To make our comparisons, average monthly minimum and maximum temperatures and precipitation patterns were averaged over a 30-year period (1986 to 2015) to establish a climate base for cities. Then we looked at how these cities would warm up by 2050, again on average over 30 years (2036 to 2065).
These projections are based on a set of climate models summarized in the Localized Constructed Analogs dataset developed by the Scripps Institution of Oceanography at the University of California at San Diego.
This scenario is based on a standard set of assumptions in climate models known as RCP 8.5. This is generally considered to be a highly estimable estimate of warming since it is expected that the world will continue on the same path of carbon emissions with limited improvements in technology or efficiency.
That is, it accurately tracks the current location and serves as a useful upper limit to what we can expect. Also, RCP 8.5 does not lead to large differences in estimates of climate change compared to other scenarios, considering the mid-century. The biggest deviations under RCP 8.5 occur around 2100.
There are some important limitations in our analysis. One reason we do not see such big geographic changes in analogous southern cities is that we do not have enough cities to compare. Our dataset covers only the continental US, but in Texas, the climate looks more like a city in Mexico, and a city in Florida may resemble an island in the Caribbean. So there were many cities in the South for which we have no matches at all. We have selected the best available matches with the data we have.
We also only compare cities based on temperature and precipitation and see which cities today are closest to the projected changes in a city by 2050. These are just two variables of dozens that define a local climate. In addition, mid-century temperature projections tend to be more robust than precipitation models, which are much more dependent on local variables and provide more uncertainty.
However, the biggest uncertainty here is the same as in all climate predictions: how fast will we respond to climate change? Whether the world is switching to cleaner energy, eating less meat, better managing land, extracting carbon dioxide from the air, or behaving as usual will mean a significant degree of future warming.
What we do from here is important to our hometowns, our country, and future generations around the world.