Two years after 200 countries, during a United Nations climate conference in 2010, agreed to control their respective carbon emission contributions to below 2 degrees Celsius or 3.6 degrees Fahrenheit, much has yet to be really accomplished, much more acted and worked on, after a new analysis from PricewaterhouseCoopers (PwC) showed the annual rate of reduction of carbon emissions per unit of GDP has exceeded a critical threshold.

In its latest annual Low Carbon Economy Index report, which analyses the developed and emerging economies' progress in lessening their respective carbon intensity, or emissions per unit of gross domestic product (GDP), PwC found that these global carbon emitters were only able to reduce emissions to a combined 0.7 per cent only in 2011, "a fraction what is required against the international commitment to limit global warming to 2°C."

To achieve the 2°C limit, the world would need to reduce global carbon intensity by an average of 5.1 per cent a year - a barometer the PwC said was never achieved since 1950 when the records first began.

"Because of this slow start, global carbon intensity now needs to be cut by an average of 5.1 percent a year from now to 2050. This rate of reduction has not been achieved in any of the past 50 years," the Low Carbon Economy Index report said.

Moreover, "governments and businesses can no longer assume that a 2°C warming is the default scenario." PwC noted investments in long term assets or infrastructure, especially in coastal or low-lying regions, need to take in hand far more pessimistic scenarios.

"The risk to business is that it faces more unpredictable and extreme weather, and disruptions to market and supply chains. Resilience will become a watch word in the boardroom - to policy responses as well as to the climate," Jonathan Grant, director, sustainability and climate change, PwC said.

"The new reality is a much more challenging future in terms of planning, financing and predictability. Even doubling our current annual rates of decarbonisation globally every year to 2050, would still lead to 6°C, making governments' ambitions to limit warming to 2°C appear highly unrealistic."

"This isn't about shock tactics. It is simple math," the report said.

Countries in the European Union gave off the highest rates of decarbonisation, according to the report. Britain, France and Germany reduced carbon intensity by more than 6 per cent in 2010-2011.

"The irony is that a key reason for lower energy use was the milder winter in the region. Both the UK and France also witnessed increased generation in low-emissions nuclear power, whereas Germany's exit from nuclear is reflected in its relatively lesser decline in emissions," PwC said.

The United States' carbon intensity in 2011 fell by 3.5 per cent, due to the shift in shale gas use.

Australia's and Japan's carbon intensity jumped in 2011 by 6.7 per cent and 0.8 per cent, respectively.

China's and India's decarbonisation, meanwhile, seems to have stalled in the last decade.