Over the past four years, the Republican Party has undergone a fairly dramatic shift in its approach to energy and environmental issues. Global warming has disappeared entirely from the party's list of concerns. Clean energy has become an afterthought. Fossil fuels loom larger than ever. And one way to see this shift clearly is to compare the party's 2008 and 2012 platforms.

It may seem difficult to believe now, but back in 2008, the Republican Party's platform (pdf) had a long and detailed section on "Addressing Climate Change Responsibly." Here's how it opened:

The same human economic activity that has brought freedom and opportunity to billions has also increased the amount of carbon in the atmosphere. While the scope and longterm consequences of this are the subject of ongoing scientific research, common sense dictates that the United States should take measured and reasonable steps today to reduce any impact on the environment. Those steps, if consistent with our global competitiveness will also be good for our national security, our energy independence, and our economy.

The 2008 platform went on to call for "technology-driven, market-based solutions that will decrease emissions, reduce excess greenhouse gases in the atmosphere, increase energy efficiency, mitigate the impact of climate change where it occurs, and maximize any ancillary benefits climate change might offer for the economy."

This language didn't just come out of nowhere. At the time, a handful of prominent Republican politicians appeared genuinely interested in tackling climate change. Then-Senator John Warner (R-Va.) was co-sponsoring legislation to reduce the country's greenhouse-gas emissions. On the presidential campaign trail, John McCain was talking up his cap-and-trade program that would put a price on carbon. (McCain, for his part, was one of the earliest members of Congress to endorse this idea.)

The 2008 GOP platform certainly didn't agree with liberals and environmentalists on everything. Far from it. The document put a heavy emphasis on nuclear power, which tends to cause some green groups to bristle (although many Democrats softened their opposition to atomic energy in the years that followed, in a failed effort to woo conservatives on climate policy). The platform also had harsh words for "doomsday climate change scenarios" and "no-growth radicalism." Yet the 2008 GOP platform was, essentially, taking part in a debate over how best to tackle greenhouse gases—not about whether the climate was changing at all.

Skip ahead to 2012, and the GOP platform takes a markedly different tone. That section devoted to climate change? Gone. Instead, the platform flatly opposes "any and all cap and trade legislation" to curtail greenhouse gases. It demands that Congress "take quick action to prohibit the EPA from moving forward with new greenhouse gas regulations." It criticizes the Obama administration's National Security Strategy for "elevat[ing] 'climate change' to the level of a 'severe threat' equivalent to foreign aggression." The platform even tosses in what appears to be a subtle swipe at climate scientists:

Moreover, the advance of science and technology advances environmentalism as well. Science allows us to weigh the costs and benefits of a policy so that we can prudently deal with our resources. This is especially important when the causes and long-range effects of a phenomenon are uncertain. We must restore scientific integrity to our public research institutions and remove political incentives from publicly funded research. [Emphasis added]

The language echoes an op-ed written by Paul Ryan in December of 2009, which  accused climatologists of using "statistical tricks to distort their findings and intentionally mislead the public on the issue of climate change." Ryan's charges were untrue; a number of subsequent investigations into the leaked Climate Research Unit e-mails found no evidence of wrongdoing by the scientists involved. Nevertheless, the insistence that research institutions lack "scientific integrity" remains intact.

It's worth noting that the GOP is moving to dismiss climate change at a moment when the scientific evidence on our warming planet continues to pile up. To take one example: In 2010, UC Santa Barbara’s William Freudenberg gave a presentation in which he revealed that “new scientific findings [since the IPCC report in 2007] are found to be more than twenty times as likely to indicate that global climate disruption is ‘worse than previously expected,’ rather than ‘not as bad as previously expected.’ ”

A more modest shift, meanwhile, has occurred in the Republican Party's treatment of clean energy sources like wind, solar, and geothermal. In 2008, the GOP platform noted that "alternate power sources must enter the mainstream," and that the way to achieve this was through "a long-term energy tax credit equally applicable to all renewable power sources." This tax credit would be worth the price tag, the platform explained, because sources like wind offered longer-term benefits "both in terms of cost and environmental protection."

Four years later, the GOP platform still promises to "encourage the cost-effective development of renewable energy," but there's no longer any explanation of how to get there. On the contrary, Mitt Romney has said that he would allow the tax credit for wind power to expire at the end of 2012. And the GOP platform now says that the Republican Party "will let the free market and the public’s preferences determine the industry outcomes."

One possibility here is that the Solyndra debacle—in which the Obama administration gave a $535 million loan guarantee to a solar manufacturer that went bankrupt—has soured the GOP on the government's ability to act as a venture capitalist, picking and choosing technologies. Yet the sort of renewable tax credits for wind and solar that Republicans backed in 2008 are a different program entirely than the loan guarantees given out to Solyndra. It would be possible to support the former and oppose the latter. But the GOP now opposes all such clean-energy programs.

Instead, much like Mitt Romney's recently released energy plan, the GOP platform focuses almost entirely on exploiting America's vast fossil-fuel resources. Looked at from one angle, that's understandable. Over the past four years, the United States has seen a surge of oil and natural gas production from places like North Dakota's Bakken Formation and the Marcellus Shale out east. New drilling techniques in shale rock could help reduce U.S. oil imports, raise the country's GDP and tamp down on the cost of electricity. With the nation's economy still struggling, those benefits are impossible to ignore.

That said, there's no reason why the recent boom in natural gas from shale, say, couldn't be compatible with longer-term efforts to reduce carbon emissions and tackle climate change. Michael Levi of the Council on Foreign Relations has been making this case for quite some time. Four years ago, the Republican platform made some effort to balance all of these competing concerns. This year, not so much.