This morning, the Obama Administration released a major report showing how climate change is already upon us. From agriculture to human health, global warming is already having wide impacts, all the evidence shows. And, of course, what's happened so far is just a prelude. It's going to get much worse unless we stop exacerbating the problem by putting more carbon into the atmosphere.
The third National Climate Assessment (NCA) is based on the work of 200 scientists and is the most comprehensive study of its type to date. Below are a few key points:
Since 1895, national temperatures have increased by between 1.3°F to 1.9°F, with most of that jump coming since 1970. Alaska has seen the biggest rises—its temperatures have risen about twice as quickly as the rest of the U.S. The Southeast has seen the smallest increases.
Warmer water expands, leading to ocean level rises. Since 1880, global levels have increased by 8 inches. By the end the century, they're set to rise by between 1 and 4 feet, going at current rates. At the same time, the ocean is becoming more acidic (carbon dioxide absorbed into water forms carbonic acid). That's particularly bad for creatures with shells, like shellfish.
California's monster drought is a taste of what many states are likely to experience. "The human influence on climate has already roughly doubled the probability of extreme heat events," the report says. The Southwest is likely to see the worst effects, leading to water shortages and, probably, more competition for resources.
Climate change increases the likelihood of heavy precipitation events. And so far, the Northeast, Midwest, and Great Plains have seen the worst of this phenomenon. The Northeast saw a 71 percent increase in such events between 1958 and 2012, for example. "Heavy downpours have frequently led to runoff that exceeded the capacity of storm drains and levees, and caused flooding events and accelerated erosion," the report says.
Droughts and heavy downpours generally aren't good for farmers. The report predicts that productivity will suffer from "direct impacts on crops and livestock from changing climate conditions and extreme weather events and indirect impacts through increasing pressures from pests and pathogens." Having said that, it may not all be bad. Climate change will reduce frost and extend growing seasons in some places, it says.
Explore more the report here using a handy guide. It doesn't make for happy reading, but the NCA is as categorical and evidence-based as it's possible to be. It really is time we started acting on its findings.