It starts with sunlight.
The sun shines on Earth, meaning that it sends radiation that passes through the atmosphere and provides warmth and light to the planet. Some of that energy is reflected back from the surface of Earth and up toward the atmosphere. Sometimes that energy passes through the atmosphere and heads back into space. Sometimes that energy encounters a gas molecule in the atmosphere, where it is absorbed. And sometimes those molecules end up expelling that energy in a random direction, including at another molecule or back toward Earth.
Understandably, the more molecules there are in the atmosphere that can absorb that energy, the more likely it is that the energy hits a molecule and is absorbed and potentially radiated back toward Earth. Also understandably, the more likely a molecule is to absorb that heat, the more likely it is to do so. So the more molecules floating in the atmosphere and the more of those molecules that are good at absorbing heat, the less likely it is that heat will escape into space. And, by extension, the more likely it will remain in the atmosphere.
This is the essence of global warming: More molecules in the atmosphere, thanks to extracting and burning fossil fuels or from decomposing organic material, means more heat trapped in the atmosphere. Which means a warmer planet. That warming leads to a number of changes in the global climate.
We can see one effect of that right now. Hurricane Florence is spinning toward the Mid-Atlantic coast, quickly gaining energy as it approaches. That energy comes from warm ocean waters, a function, in part, of the oceans absorbing more heat than in the past, thanks to a warmer climate.
Our Chris Mooney explains the science behind the increase in gigantic, powerful storms:
There are many relatively weak [hurricanes] — Category 1 and 2 — but also many dangerous and intense storms with winds that exceed 130 mph.
The difference between the two groups, prior research has found, is often a difficult-to-forecast process in which the hurricane rapidly strengthens, usually in the presence of highly favorable environmental conditions, such as extra warm seas to considerable depths, lots of available humidity in the air and slack winds around the storm.
Because warmer ocean conditions are exactly what climate change is expected to produce, it has been natural to wonder whether more fast-intensifying storms will be in the offing. Now, the new research has suggested that this will indeed be the case.
Most of the greenhouse gas in the atmosphere is carbon dioxide, and most of the greenhouse gas produced in the United States comes from burning gasoline in cars and trucks (28 percent of emissions in 2016) and burning fossil fuels for electricity (an additional 28 percent).
This week, the New York Times reported on a new proposal expected shortly from the Trump administration. President Trump's team has already announced plans to scale back higher fuel efficiency standards and rescinded a plan by President Barack Obama that would have cut back on greenhouse gas emissions at existing coal-burning power plants. The new change would roll back regulations mandating that fossil-fuel extractors — that is, oil and gas companies — have to track and contain methane that escapes during the extraction process.
Scientists have a metric to evaluate the extent to which molecules will play a role in absorbing heat called “global warming potential.” A molecule's GWP is a measure of how effective it is at absorbing heat and how long it lasts in the atmosphere before breaking down. Molecules are measured against carbon dioxide, which is assigned a GWP of 1. Methane is assigned a GWP of 28 to 36 by the EPA — meaning it has 28 to 36 times the global warming effect of carbon dioxide over the span of a century. Methane is much better at absorbing radiation than carbon dioxide. It also breaks down faster than carbon dioxide, so over a shorter period of time, its GWP is even higher since less of it hangs around for 100 years.
On Wednesday, the Energy Information Administration announced that the United States became the world's largest producer of crude oil earlier this year. You'll notice on the graph below that American production surged not under Trump but under Obama, in about 2012 or so.
Why? Fracking. Technically known as hydraulic fracturing, the fracking process involves drilling long, horizontal channels in shale formations. A water-based mixture is forced in and the rock cracks, releasing oil and gas. The technology that allowed this to work effectively was developed relatively recently — it began to expand and developed here, so we've seen a boom where other countries haven't.
That boom in extraction has meant a boom in methane production in the form of natural gas. Some portion of that gas escapes into the atmosphere at the drilling site, where it gets to work being 28 to 36 times as effective at capturing heat as its more numerous carbon dioxide neighbors.
Natural gas production in the United States began to rise thanks to the fracking boom in about 2006. That's about the time period when atmospheric methane levels began to increase after remaining flat for about a decade.
Obama, worried about climate change, wanted to ensure that as little methane as possible was escaping. Trump, not worried about climate change, is acquiescing to the industry's argument that the methane rules were unduly burdensome. Those burdens haven't kept the United States from seeing an explosion in production, certainly, but Trump promised to aid the energy industry on the campaign trail and he has kept that promise since arriving in Washington.
"That administration trusted environmentalists,” one energy industry official told the Times about Obama. “This one trusts industry."
That's a formulation that's both hard to debate and which will be interpreted in different ways by different people.