The White House will be going hard on climate change all week, thanks to a new National Climate Assessment report looking at what climate change means for the U.S., short and long-term. And surprise: researchers had no trouble documenting the already present effects of rising global temperatures on the country, region by region.
In a sense, the findings of the government's report aren't news, thanks to several studies documenting changes in, for example "extreme precipitation," over time. We've even had climate change maps of the U.S. before. But this report is why you'll see President Obama giving interviews to meteorologists on the local news tonight. Climate change is a global issue, but recent reports, including this one, have tried to emphasize just how local and observable it is. Here's a key paragraph from the report:
“Americans are noticing changes all around them. Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours. People are seeing changes in the length and severity of seasonal allergies, the plant varieties that thrive in their gardens, and the kinds of birds they see in any particular month in their neighborhoods.”
All that with a rise of just 2 degrees Fahrenheit in global temperatures.
According to the report, the Northeast has been blessed with the greatest increase in extreme precipitation, compared to every other part of the country. From 1958 to 2010, that's a 70 percent increase in "the amount of precipitation falling in very heavy events." That increased rain and snow, along with rising sea levels on the Northeast coast, will translate into more flooding across the region. New Englanders don't need to be told that the infrastructure in the area is on the older side, or that the increased flooding that's happening already has challenged that infrastructure.
There's another major effect the Northeast is already feeling: increased heat waves. And that's going to get worse, no matter what we do. Look at the map above, provided by the study. As you can see, climate change is threatening to burn up Maryland with dramatically more days over 90 degrees per year. Compared to that number at the end of the 20th century, the southern Northeast could be looking at more than 60 additional days a year of heat-wave level temperatures, the study notes. New York City doesn't look that cool either. The map presents two scenarios, "high emissions" and "low emissions" projections for the number of likely 90 and above days in the years 2041 to 2070. If we dramatically cut emissions, we're still looking at a lot more hot days in the summer. If we do nothing, it'll be even worse.
As is true in many regions, the changes in climate will negatively impact the region's farming, and fishing industries, and its ecosystems.
The report's authors are sure of one thing for this region: it will see a dramatic increase in the number of extra-hot days per year, with the intensity of that change depending on whether we reduce emissions or not. However, the science is less clear on what climate change will bring for the region precipitation-wise, in part because the Southeast seems to straddle the border between two different scenarios:
Because the Southeast is located in the transition zone between projected wetter conditions to the north and drier conditions to the southwest, many of the model projections show only small changes relative to natural variations. However, many models do project drier conditions in the far southwest of the region and wetter conditions in the far northeast of the region, consistent with the larger continental-scale pattern of wetness and dryness.
The effect is also less certain on the region's already extreme weather events, like hurricanes and tornadoes. The researchers note that the recent increase in tornadoes across the region is not statistically significant. Hurricanes, however, could become fewer in number yet more intense and therefore damaging. That, combined with rising sea levels, should be worrisome to the region's low-elevation coastal communities, who are particularly vulnerable to coastal flooding.
The Midwest is one of the few regions that will see a positive effect from climate change: longer growing seasons. However, the researchers note, there will also be more extreme weather events hitting the same areas, meaning that all those crops will be at risk anyway. Overall, the additional stresses on the Midwest will "alter the ecosystem and socioeconomic patterns and processes in ways that most people in the region would consider detrimental." Like almost everywhere else, that will include hotter summers. That's not great for two of the region's key crops: corn and soybean.
Meanwhile, climate change has and will continue to alter the forest composition in the region. The habitats for many of the regions trees will move northward.
The Midwest is also responsible for emitting greenhouse gasses at a rate 20 percent higher than the rest of the country, meaning that the region has an increased potential to dramatically impact a reduction in the country's emissions as a whole.
"Even under a scenario of substantial reductions in heat-trapping gas emissions," the report says on the Great Plains region, "days over 100°F [are] projected to double in number in the north and quadruple in the south by mid-century." The stresses produced by that change will "more than offset" the single benefits a longer growing season and warmer winters.
The Great Plains, like the Southeast, won't see just one change in precipitation levels. While the northern part of the region will probably end up with more precipitation, according to their projections, "Large parts of Texas and Oklahoma are projected to see longer dry spells."
Although the increased precipitation in the north will help the agricultural industry there, things look a little more bleak for the southern part of the region. Dry spells combined with increased evaporation from those dramatically higher temperatures will exacerbate the stress on the region's water supply.
The hottest and driest region in the U.S. will get, well, hotter and drier. The region that produces more than half of the nation's high-value specialty crops is staring down a future of increased temperatures, decreased rain and snowpack, and increased insect outbreaks. Oh, and those wildfires? They'll get worse, too.
"The region has heated up markedly in recent decades, and the period since 1950 has been hotter than any comparably long period in at least 600 years," the report says of the already dramatic effects of climate change on the region. Here's more:
There is mounting evidence that the combination of human-caused temperature increases and recent drought has influenced widespread tree mortality, increased fire occurrence and area burned, and forest insect outbreaks. Human-caused temperature increases and drought have also caused earlier spring snowmelt and shifted runoff to earlier in the year.
Like its neighbors to the south, the Northwest will experienced increased stresses on the water supply with changes to the timing of snowmelt streamflows to the region. The area is already experiencing increased tree die-off, and under a higher emissions scenario, "extensive conversion of subalpine forests to other forest types" is likely by 2080:
While increased area burned can be statistically estimated from climate projections, changes in the risk of very large, high-intensity, stand-replacing fires cannot yet be predicted, but such events could have enormous impacts for forest-dependent species. Increased wildfire could exacerbate respiratory and cardiovascular illnesses in nearby populations due to smoke and particulate pollution
The Northwest has gotten away with relatively low increases in temperature so far, the report says, along with no statistically significant changes in precipitation. However, rising sea levels will put many of the region's coastal populations at risk, thanks to their low elevations.