THE carbon express is rolling. While a political brawl over emissions trading gets more farcical, events at home and abroad keep us focussed on the rapid developments in this new industry.

An Australian Farm Institute study released last week found the Federal Government's Carbon Pollution Reduction Scheme could cost the farm sector $2.4 billion a year by 2020, and $10.9 billion a year by 2030.

Critics will dive into the numbers but it is important that industry continues to have a stab at what emissions trading will do to agriculture as more details on the policy seep out.

It shows what is at stake if we do nothing, and if we go into this alone.

Many policy variables will determine the responses of the farm sector to a new regime, including how emissions are measured, who is accountable for them and the timeframe in which free entry on to the carbon playing field will convert into an obligation.

The infamous modelling by the Government was based on a world economic order that has now been shattered.

The uncertainty caused by the meltdown may or may not change the way in which commodity trading systems work in the future, or how sensitive industries are to adjustment.

The AFI study does not assume a utopia wherein the whole world gleefully steps into a compatible trading system.

A unilateral lowering of trade barriers might in theory seem to have a far better chance of getting off the ground now as the world's leaders look for ways of unfreezing financial flows to stimulate business recovery.

Protection of jobs, consumers and farmers now stands in the way of that deal.

One of the last things anxious politicians anywhere want is committing to a system that adds to household and business costs without an ironclad assurance that everyone will be in the club - and that it will actually reduce world pollution anyway.

But an ambitious new US president has boosted hopes of supporters of a global climate change agreement and free trade in carbon credits by last week putting forward a plan for the US to establish a "cap and trade" carbon trading system by 2012!

All of a sudden it is the US which is at the forefront of the international climate taskforce, raising hopes that an effective international agreement might be possible.

Obama's plans were fleshed out in his new administration's proposed four-year budget which assumes revenue of $80 billion annually from selling carbon allowances from 2012.

That's a very far cry from his predecessor who no doubt still thinks that climate change was the subject of a sci-fi film starring Al Gore.

Meanwhile there is a huge amount to do regardless of the Obama effect, as the Rudd Government now seems trapped in this policy.

Last week, Federal Agriculture Minister Tony Burke unveiled $27 million in spending on 18 projects over four years as part of its climate change research program.

Agribusiness doesn't actually have four years to work out how to measure, operate and mitigate in the new world, if current timelines hold.

If Barack Obama leads the world into a climate-friendly future, we have even less time.