Tony Juniper: Never mind the credit crunch, what about the climate crunch?

The budget had most of the key green catchphrases, but whether it lays the foundations for a truly green economy is a different matter.

Welcome were the commitments to energy efficiency, additional money for offshore wind and other renewable power technologies and incentives for the use of combined heat and power. It was good to hear the fuel duty escalator will remain and that there is now at least some recognition of the need to build a skills base in the cutting-edge green technologies for the future. So there was a green thread, although most of it was vague. The details will be vital, however. Some of Britain's renewable power companies are in crisis because of past policy bungles, and one test of the success of this Budget will be if they once more begin to grow.

Less welcome was the implicit view in the budget that we can rebuild the old consumerist economy – only with a few green knobs on, and that all will be fine. Also less welcome was the absence of any real sense of urgency as to the nature of the crisis we face. While the credit crunch and recession dominated Mr Darling's announcement, the climate, resources and nature crunches that could cause quite profound problems in the near future were hardly acknowledged.

For example, the commitment Mr Darling announced to put in place a 34 per cent carbon dioxide reduction target for 2020 is not sufficient. To have any chance of remaining below 2 degrees of average global warming (the UK and EU's official target), a cut in excess of 40 per cent is needed. And much of the 34 per cent target will be met through credits generated overseas. In other words, the Budget lacked science-based ambition and again put off the inevitable scale of change that we need to make.

While politics is about compromise, the atmosphere knows only limits. And while the economics is all about growth, Nature still suffers massive depletion. These fundamental truths still did not penetrate into the substance of the Budget, even though the science now tells us that we need fundamental transformations if we are to navigate the sustainability challenges that lie ahead.

The Budget should have been the moment to unite the previously disparate economic and sustainability agendas, but instead was one more attempt to shore up a deeply flawed economy system with some modest nods toward green job creation.

The Budget was greener than it might have been, but did not signal the scale of change needed to match the challenges we face. It is not only a financial debt that our children will inherit from our present approach to economics; they will at this rate also suffer the consequences of a rapidly changing climate and depleted natural resources.

Tony Juniper is the Green Party parliamentary candidate for Cambridge