Drought is the slow-motion natural disaster—the kind that’s easy to overlook as it’s happening—but what hit the U.S. corn belt this summer was so historic that it was impossible to miss. As of mid-October, nearly three-fourths of the U.S. was in some state of drought, and the extreme dryness took a terrible toll on crops. Corn yield per acre is on track to be down 25% below normal, while soybean yields are down by 14%. Approximately 2,500 counties nationwide had to receive some form of disaster relief because of the drought, which is likely to cause retail food prices to rise 3 to 4% next year. Worst of all, the climate change problem is only getting worse, so this year’s drought may just be a taste of what a warmer world has in store for the American breadbasket.

Genetically modified crops are everywhere in the U.S.—some 85% of corn, the staple crop in the U.S. food system, is genetically modified. Though mainstream scientific research says that GM foods are harmless, a growing number of environmentalists still view them with suspicion. Hence California’s Proposition 37,  on the ballot in November,  which would have required the labeling of all foods made with genetically modified ingredients. Though the pro-Prop 37 forces—led by prominent food writers like Michael Pollan—held an early advantage, the proposition ended up losing, thanks in part to tens of millions of dollars in campaign spending by agricultural companies like Monsanto.

Cap and trade died an ignominious death in the U.S. Senate in 2010, when proponents were unable to bust a Republican-led filibuster threat. Even after President Obama’s re-election, federal climate action still seems like a long shot. But ultra-green California is a different story. Six years ago, the state legislature passed Assembly Bill 32, designed to establish a statewide cap on carbon emissions from industry. After years of legislative wrangling and one failed ballot challenge in 2010, the law was at last set to go into effect at the end of 2012. Businesses will need to figure out how to reduce their carbon emissions gradually over the coming decade—and if AB32 is successful without crippling California’s economy, it could pave the way for real federal action on global

Every U.S. President since Richard Nixon has promised to get America off foreign oil—and yet, American dependence on imported crude only seemed to grow. But in 2012 that changed definitively. Thanks in part to new sources of shale oil in North Dakota and Texas—as well as conservation efforts to reduce oil consumption—the U.S. has enjoyed a major domestic oil boom. By November the country was producing 6.68 million barrels of oil a day, the highest level in 18 years—enough to make it a net exporter of petroleum products. By some estimates, the U.S. might eventually overtake Saudi Arabia as the world’s biggest oil producer. But the boom has its dark side—shale drilling requires hydrofracking, which may pollute local water supplies.

5. The Battle Over Keystone XL

By Bryan Walsh Dec. 04, 20121 Comment

The domestic oil boom in the U.S. is getting a big boost from a major new supply of crude imported from the friendly neighboring nation north of the border. But Canadian crude from the oil sands of Alberta—or tar sands, as environmentalists call it—also comes with a heavy environmental cost, both in terms of local water pollution and greater carbon emissions. That led greens to oppose the construction of the Keystone XL pipeline, which would have transported hundreds of thousands of barrels of oil sands crude down to the U.S. At the same time, Republicans—and more conservative Democrats—were pushing for the pipeline as another step towards continental energy independence. In the end, President Obama decided to block the project temporarily—but with re-election assured, he may take a second look at Keystone.

6. Arctic Sea Ice Melts to Record Low Levels

By Bryan Walsh Dec. 04, 2012Add a Comment

Climate change has always happened faster in the Arctic than anywhere else,partly because of a sort of accelerating feedback loop. Reflective ice absorbs less heat than dark sea water, so as ice cover gets smaller and smaller, the water gets warmer and warmer. But what happened to the North Pole in 2012 was record-breaking. Arctic sea ice—the ever-changing cap over the top of the globe—melted this summer to just 1.32 million sq. miles (3.41 sq. km), the lowest level since satellite records began in 1979. This year’s minimum extent is 50% smaller than the average between 1979 and 2000. And the melting is unlikely to stop—scientists believe that the Arctic itself could be ice-free during the summer as early as the end of the decade.  That has an additional effect on warming—white sea ice reflects sunlight back into space, while dark open water absorbs it, further speeding global warming in a feedback process.

Climate change is going to have a number of unpredictable effects, but here’s we know: it’s going to keep getting warmer. We saw that in 2012, which is on track to be the hottest year globally on record, going back well into the 19th century. The winter was particularly hot—normally snowbound parts of the U.S. like Minnesota and North Dakota experienced days of mild temperatures. By the summertime, it was miserable—July was the hottest single month ever in the U.S., which only intensified an unusually brutal drought. The year just past will almost certainly be a record-breaking year—but don’t expect that record to stay unbroken for long.

Evidence of global warming was everywhere in 2012—except for the Presidential election. During the campaign, climate change virtually disappeared as an active issue, with Republican Mitt Romney mocking even the suggestion of climate action, while Democrat Barack Obama mostly ignored it. That was chiefly due to the bad economy, which sucked up most of the campaign season’s energy and voter attention. But it was also a mark of how politically polarized climate has become in national politics—and a sign of just how difficult it will be to get the momentum needed to do something at last about what might be the problem facing humankind.

The record melting of Arctic sea ice wasn’t just a sign that climate change was real and happening. It was also an opportunity—ironically, for the very companies responsible for much of that warming. This September, with the blessing of the Obama Administration, Shell began drilling an offshore oil well about 70 miles (113 km) off Alaska’s northern coast. The effort quickly hit a snag: ice in the water led Shell to suspend the operation until the summer of 2013. But make no mistake—there are billions of barrels of oil in those Arctic waters, and the drilling ships will be back. Given the damage a spill could do in the remote and bitterly cold waters of the Arctic, that scares environmentalists.

No, we can’t say exactly how much responsibility man-made global warming bears for the massive storm that slammed into the Northeast at the end of the October, killing over 100, flooding chunks of New York City and leaving more than 8 million people without power. But we do know that climate change—especially because of rising sea levels—is likely to make the Sandys of the future that much more dangerous. One thing should be clear: with nearly 4 million Americans living within a few feet of high tide, we need to better prepare our coastal cities for the storms to come.