A lot of questions swirl around the subject of global warming.
Here's the main one: Is it really happening?
Despite skeptics and dismissals, an increasing body of scientific work appears to confirm warming and its impacts.
Recently, two major reports added considerable weight to the warming argument. The first — the most comprehensive study of polar ice ever — shows the planet's ice sheets are melting at an accelerating rate.
The impact of this change varies, the report published by the journal Science notes. Most dramatic are changes seen in Greenland, while Antarctica's melt is occurring much more slowly. Yet the receding ice sheets are adding to rising sea levels.
The second report, from researchers with the Global Carbon Project, says that 2011 was a record year for increases in carbon dioxide emissions. And 2012 is expected to surpass that level.
Carbon dioxide, of course, is the most common "greenhouse" gas believed to contribute to global warming. The amount of this gas pumped into the atmosphere rose 3 percent in 2011 and is expected to be 2.6 percent higher this year.
This latest data on carbon dioxide comes at a time nations are supposed to be cooperating on efforts to scale back its production. While modest success is seen in certain industrialized nations — including the United States — other countries, most notably China and India, are more than making up the difference with even greater carbon contributions.
The ongoing increases in carbon dioxide production indicate that international goals to limit global temperature increases to 3.6 degrees are quickly becoming unattainable, the Global Carbon Project states. Despite ongoing talks and pledges, real action on the matter is hard to come by.
Even as official rejection of global warming melts away with Greenland's glaciers, there is still stiff resistance to calls for action. In some circles, warming is tied to natural phenomena, rather than human activity. Conversely, even among people who acknowledge the human factor in warming, many argue the overall impact on the planet will be minimal.
What will happen as a result of global warming is indeed a matter of widely diverging debate. That's because it's far easier to assess what has happened to the planet than it is to predict changes in the future.
Computer models — which depend on the information supplied to them to offer results — provide possible impacts that range from minimal to catastrophic. The fact is, we don't know how bad global warming will be.
But melting ice sheets raise a concern. Right now, ice and snow at the poles reflect sunlight back into space, thus lowering the planet's temperature.
As these ice sheets melt, their reflective abilities decrease, possibly producing even greater warming.
A common question about warming involves how hot things will get. But what if warming is an ongoing process? And what if it occurs at a far faster rate than previously envisioned?
Some critics of environmental action to stem greenhouse gas emissions say more evidence is needed to show carbon dioxide is a culprit.
But considering all that's at stake, maybe it's time to demand proof that humans are not making the planet grow hotter.
Otherwise, that data now pouring in points to a growing need to reverse our carbon course.
Mitchel Olszak is a columnist for the New Castle (Pa.) News.