How the politics of climate change have changed! By contrast, over the past 20 years, climate change policy has not changed as much as you might think.

Save for the period Tony Abbott was opposition leader, over the past two decades, both the major political parties have implemented and supported policies designed to lower Australia's greenhouse gas emissions.

John Howard first ramped-up the push to put more renewable energy into the system in 2001.

His Mandatory Renewable Target (MRET) sought to grow the share of renewable power in the system to two per cent and then five per cent of generation.

It did so by issuing certificates to those producing renewable energy from large-scale generation projects and insisting retailers either purchase more renewable energy or purchase certificates.

A decade later, a Labor government further legislated to raise the target to 20 per cent.

The MRET (later the RET) was a screaming success. Its mission is complete.

In the lead-up to the 2007 election, Labor declared that a more ambitious program was needed and promised to introduce an "Emissions Trading Scheme".

Kevin Rudd read the national mood well and by election day John Howard was forced to make a similar commitment.

It wasn't enough to save his ageing government, but following Rudd's 2007 win, the Coalition's new leader Brendan Nelson maintained the Coalition's commitment to meaningful action. Malcolm Turnbull did so too, but his attempts in government to secure party room support for various mechanisms designed to constrain carbon output failed.

Tony Abbott has also been part of the policy commitment. In opposition, he blocked Rudd's Carbon Pollution Reduction Scheme (CPRS) and took a wrecking ball to Julia Gillard's Carbon Pricing Mechanism (CPM), which he labelled a "carbon tax".

But in government, after successfully repealing the CPM, he introduced his own cap and trade scheme.

It's called the Safeguard Mechanism and still exists today.

Having railed against a "carbon tax", Abbott introduced one himself.

Arguably not one a meaningful one, but a "cap and trade" system just the same.

So when you look through all the politics, the major parties have been pretty consistent in their recognition of the climate change problem and each has remained committed to policy mechanisms to address it for most of the last twenty years.

So how could an issue capable of establishing so much policy consistency across the political divide, generate so much toxic political debate?

How could it have played a part in the demise of arguably, five parliamentary leaders on both sides of the political divide? And why has the political dynamic changed so much?

The toxicity of the debate and the number of political casualties is easy to explain. We live in an energy-intensive economy and are served by a parliamentary democracy with three-year electoral cycles - so inviting of political opportunism.

The reasons for the change in the political dynamic are more numerous and complex.

First of all, pressure to take more meaningful action on climate change was always going to increase over time, both domestically and globally.

Second, and without lowering its commitment or ambitions, after almost a decade in opposition Labor has learnt not to leave itself so open to misrepresentation and political attack.

Third, having taken the target off its back, Labor has denied the Coalition a distraction from the main game.

While all the attention has been on Labor, there has been too few column centimetres left to highlight the Coalition's pedestrian approach. The Coalition parties have now been left to fight among themselves. That always commands media space.

Finally, the advances in technology since the Climate Wars began have been substantial. That has taken the focus off cap-and-trade mechanisms as a solution.

Rather than argue about how we price carbon and punish emitters, we now spend more time talking about how innovation can be accelerated.

This will enable hydrogen to be produced more cheaply sooner and make electric cars more affordable and popular.

Additionally, it will allow a greater focus on which low-emissions technologies might be worthy of government investment support, and how our natural landscapes might be improved to allow for the greater absorption of carbon from the atmosphere.

Carbon constraints no longer feature much in the debate, although the Business Council of Australia has canvassed changes to the Safeguard Mechanism, which both broaden its scope and lower its tolerance of emitters.

Whatever the causes, the change in politics is a good thing. It may both path the way to action commensurate with community expectations and finally put an end to the Climate Wars. Climate change policy can only be meaningful if it's long-lasting and not subject to repeal after a change in government.

In other words, when all the politicians decide climate change is a policy issue more than a political opportunity, we will secure some meaningful and long-lasting action.

The lowering of the political temperature now offers us the best chance to do so in a long time.