With all eyes riveted on the debt talks and efforts to avert an economy-busting government default, little attention is being paid to another debt that is similarly ballooning out of control and threatening to spur its own economic chaos.

The carbon debt. Those pesky greenhouse gas emissions that we spew to power our businesses, drive our cars and heat and cool our homes are accumulating in the atmosphere like an unpaid bill with compounding interest.

Economists now say that the bill for all that unchecked carbon pollution is a lot bigger than previously thought -- and that the longer we wait to pay it, the more it's going to cost us.

A new peer-reviewed report released this week by the Economics and Equity for the Environment (E3) network found that each ton of carbon dioxide emitted in the atmosphere results in as much as $893 in economic damages, far greater than the government's current estimate of $21 per ton.

This figure, known as the "social cost of carbon," is used by federal agencies when weighing the costs and benefits of carbon-reducing regulations, such as appliance efficiency standards or fuel economy standards for cars and trucks. It's an estimate of the monetary damages caused by higher global temperatures, such as extreme weather events, rising sea levels, agricultural losses and wildfires.

The government's substantially lower social cost of carbon -- which E3 calls "fundamentally flawed" and a "gross underestimate of the potential impacts of climate change" -- means that it is much harder to justify more stringent regulations to limit carbon pollution.

E3's new report further concludes that, "it's costing us more to do nothing about climate change than it would to adopt mitigation measures."

"Investing in reducing our emissions is clearly the prudent option," says Frank Ackerman, an economist with the Stockholm Environment Institute and a report author. "It's the difference between servicing your car, or waiting for it to break down on the highway."

A second report released the same day by the World Resources and Environmental Law institutes similarly agrees that the government's model for estimating a social cost of carbon oversimplifies assumptions about climate change and discounts the costs of future mitigation, resulting in an underestimate of true costs.

But look no further than recent headlines for real-world proof that government economists may be low-balling the costs of climate change.

Earlier this week The New York Times reported that unprecedented drought and heat across 14 states from Florida to Arizona is creating huge agricultural losses expected to exceed $3 billion in Texas alone and exacerbating long-standing water feuds between southern states.