Britain's carbon emissions grew faster than the economy last year for the first time since 1996, as a cash-strapped population relegated the environment down its league of concerns and spent more money keeping warm, according to a new report.  The rise in Britain's so-called carbon intensity increases the danger that the country will miss legally binding targets on reducing emissions, warns PricewaterhouseCoopers (PwC), the consultancy behind the report.  Furthermore, it found that Britain's rising carbon intensity is part of a worldwide trend which threatens to push global warming above a two-degree Celsius increase on pre-industrial levels.  This is the temperature that the G8 group of leading economies has pledged not to breach in the hope of avoiding the worst consequences of climate change.  Leo Johnson, partner for sustainability and climate change at PwC, said: "Our analysis points unambiguously towards one conclusion, that we are at the limits of what is achievable in terms of carbon reduction.  "The G20 economies have moved from travelling too slowly in the right direction to travelling in the wrong direction. The results call into question the likelihood of global decarbonisation ever happening rapidly enough to limit global warming to 2 degrees Celsius," Mr Johnson added.  Experts calculate that limiting