The International Energy Agency (IEA) has released unpublished estimates of 2010 global carbon dioxide (CO₂) emissions, and the news is not good.

Between 2003 and 2008, emissions had been rising at a rate faster than the IPCC worst case scenario. However, the global recession slowed the emissions growth considerably. In fact, they actually declined slightly from 29.4 billion tons (gigatons, or Gt) CO₂ in 2008, to 29 Gt in 2009.

However, despite the slow global economic recovery, 2010 saw the largest single year increase in global human CO₂ emissions from energy (fossil fuels). They grew a whopping 1.6 Gt from 2009 to 30.6 Gt. The previous record annual increase was 1.2 Gt from 2003 to 2004.

As illustrated in Figure 1, in 2009 we had dropped into the middle of the IPCC Special Report on Emissions Scenarios (SRES) scenarios, but the 2010 increase has pushed us back up toward the worst case scenarios once again.

Currently, in terms of both cumulative and annual emissions, we are on track with Scenario A2, the description of which matches what’s happening in the real world fairly accurately thus far:

• Relatively slow end-use and supply-side energy efficiency improvements (compared to other scenarios).

• Delayed development of renewable energy.

• No barriers to the use of nuclear energy.

The major exception is that several countries are transitioning away from nuclear power in the wake of the Japanese Fukushima disaster. This could slow emissions reductions even further.

So, what does continuing on our current path look like?

Scenario A2 puts us at 850 ppm atmospheric CO₂ in 2100, with an average global surface temperature 3.5°C hotter than in 2000 (more than 4°C above pre-industrial levels).

If we return back up to Scenario A1FI (fossil fuel intensive), which we were exceeding until the global financial crisis, we’re looking at 950 ppm CO₂ and 4°C global warming over the 21st Century (more than 4.5°C above pre-industrial temperatures in 2100).

Clearly this is very bleak news. In an interview with The Guardian, IEA Chief Economist Fatih Birol said:

“I am very worried. This is the worst news on emissions…It is becoming extremely challenging to remain below 2 degrees. The prospect is getting bleaker. That is what the numbers say.”

Indeed, limiting global warming to 2°C above pre-industrial temperatures, which is considered the “danger limit” but which may even be too risky, is a challenge to achieve even in the most optimistic IPCC CO₂ emissions scenarios.

In fact, the UK Hadley Centre Met Office recently found that just to limit global warming to 3°C, we should have started taking serious action to reduce emissions in 2010 (Figure 4).

Right now we’re on track with the orange and red arrows in Figure 4. If we continue with this business-as-usual high emissions path, the consequences could be dire.

Some of the impacts listed in the IPCC report for global warming of 3–4°C above pre-industrial levels include:

• hundreds of millions of people exposed to increased water stress

• 30–40% of species at risk of extinction around the globe

• about 30% of global coastal wetlands lost

• increased damage from floods and storms

• widespread coral mortality

• the biosphere – soils, plants etc – stops absorbing carbon and starts releasing it

• reduced cereal production

• increased death and illness from heat waves, floods and droughts.

The IEA also found that about 80% of the power stations likely to be in use in 2020 are either already built or under construction. This means we’re “locked in” for continued emissions from these power plants, which constitute about one-third of global human CO₂ emissions from fossil fuels.

So it’s going to be difficult to transition off of these high emissions scenario paths, and we’ll have to find wiggle room in other sectors like transportation.

Birol said that this alarming news should serve as a “wake-up call” for international climate negotiations and other emissions reduction efforts:

“This should be a wake-up call. A chance [of staying below 2 degrees] would be if we had a legally binding international agreement or major moves on clean energy technologies, energy efficiency and other technologies.”

These findings should serve as an alarm bell to warn us that our window of time to avoid potentially catastrophic consequences from climate change is running out fast.

We need to get on track with the green arrow in Figure 4: immediate and rapid action to reduce global carbon emissions.

This story was co-authored by Dana Nuccitelli. Dana is an environmental scientist and a writer for the climate science blog Skeptical Science.