In the last of its series of reports on the state of our climate change knowledge, the Intergovernmental Panel on Climate Change (IPCC) warned that the world is perilously close to overshooting a previously agreed upon target for slowing worldwide temperature increase, according to the text of the report’s Summary for Policymakers released in Berlin Sunday.

If nations do not commit to reduce aggregate emissions 40 percent by 2050, there is an even chance the rate of planetary warming will be such that the world will not be able to avoid expensive and extremely damaging effects.

As explained previously, the IPCC is conducting its assessment of the scientific literature on climate change, the first assessment since 2007. This particular report tackles mitigation, defined as “a human intervention to reduce the sources of enhance the sinks of greenhouse gases.”

Unfortunately, the years 2000-2010 saw the greatest concentration of greenhouse gases in human history, 78 percent of which was directly attributable to carbon dioxide emissions, driven by population and economic growth both increasing demand in the  electricity, industry, and transportation sectors, all of which, despite growth in renewables, rely primarily on fossil fuels.

Based on the state of the research and these conclusions, there is a high probability that, without significant policy changes, the world will not be able to abide by the commitment made at the Copenhagen Climate Summit in 2009 to limit global temperature rise to two degrees celsius above pre-industrial levels.

Warming above these limits, which a 2012 World Bank report believed was plausible with the current emissions pathway, would cause “unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on human systems, ecosystems, and associated services.” What is worse, in the World Bank’s estimation, is that adaptation to such severe warming trends may not even be possible.

Unfortunately, any effort to forestall this eventuality would necessitate capping the emissions of greenhouse gases (carbon dioxide and some equivalents, such as methane) to 450 parts per million by 2100 (for reference, the estimated concentration in 2011 was 430 parts per millions). Such a reversal in our emissions pathway would require a radical change in the sources of electricity generation, including a possible quadrupling of renewable and zero-carbon electricity generation, the widespread adoption of nuclear power, and investment in carbon capture and storage technologies for any remaining exploitation of fossil fuel resources.

Any delay in these efforts, the IPCC warns, would only raise the cost of future mitigation, as well as limit the possible scenarios for avoiding future catastrophic warming. Actions taken today which do not follow a low- or net-zero carbon pathway (such as the continued construction of coal-burning power plants without carbon storage) risk “locking-in” future emissions sources for decades, further undermining the chances of success.

Progress on developing and implementing mitigating technologies has been slow. The adoption of carbon capture and sequestration for power plants is still not market-ready. Analysis from the Congressional Research Service’s Peter Folger demonstrates that much of the research and development activity in its earliest stages, and the systems that are closer to deployment are prohibitively expensive to adopt.  

While renewable energy has made impressive leaps integrating itself into the energy market, there are still many places where they require outside support (through subsidies or renewable energy mandates). Nuclear power, additionally, suffers from a legacy of catastrophic accidents, most recently in Japan, which increase the barriers for its widespread use. A major part of the problem is that there are no policies in place, such as carbon pricing or aggressive emissions regulation, to push the market in this direction.

While the IPCC does not “endorse” any specific decisions on mitigation, it does highlight how behavior change, especially with regard to energy demand, is the key factor in how quickly we can set ourselves on the correct carbon pathway.

Currently, the emissions damage done by fossil fuels, including coal, is not priced into market cost of using such sources for power generation. Changing these market signals, through a carbon tax, cap-and-trade, or government regulation, would be required to make the expense of fossil fuel usage reflect its climate damage.

As yet, there is little political appetite in the United States to factor in these costs. And, perhaps more importantly, countries in the developing world are reluctant to forgo using fossil fuel resources they may have in abundance, a step which would constrain economic growth in their own countries.

While the UN Framework Convention on Climate Change has raised awareness of these issues, there still does not exist a global consensus for coordinated, concerted action that would set the world on a reduced carbon emissions pathway. What this latest IPCC report makes clear is that such an effort is necessary sooner rather than later, if we are to have any chance of avoiding a future of highly damaging warming trends.