If the UN summit on climate change in Copenhagen ends with an agreement on legally binding targets (which it almost certainly won't), the hard work of implementation would still need to be done. Targets have value - they focus political, business and media attention - but they don't automatically lead to delivery.
Look at Kyoto. The fairest overall assessment of it is that the developed countries which ratified the protocol have allowed their emissions to increase by 9.1 per cent, while the US allowed its emissions to increase by 14.4 per cent. Kyoto can plausibly be said to have reduced non-US, developed-country emissions by about 5 per cent from what they would have been without the deal, which is better than nothing. But it's not nearly enough.
The EU's target of a 20 per cent reduction in greenhouse-gas emissions by 2020, though still not enough, is at least enforceable. And the EU has significant policy levers - regulatory powers and money to invest in clean energy. So, even though Copenhagen is important, the EU Council of Ministers is the crucial forum for UK politicians wanting to control climate change.
The EU has led international negotiations on climate. Its commitment to reduce emissions is not dependent on what anyone else does. Its target to get 20 per cent of all energy from renewables by 2020 is achievable and it has the money to help construct the more extensive and efficient infrastructure needed, including grids across the North Sea and the Mediterranean. It has also said that it will have up to 12 large-scale carbon capture and storage (CCS) plants operational by 2015. Although this is just a target and the words "up to" are classic fudge, the Commission has already allocated more than €1bn (£910m) to CCS projects under the European Economic Recovery Plan and has selected the projects to receive the money, which national governments seem to find hard to do.
There is no significant disagreement between the UK's main political parties about climate change, but there certainly is disagreement over the EU. New Labour has generally been pro-EU; the Liberal Democrats are very pro, but the Conservatives remain divided (though David Cameron's sensible decision not to hold a referendum on the Lisbon Treaty failed to produce the ructions that some expected, or hoped for). Cameron and the shadow energy secretary, Greg Clark, are serious about controlling climate change. But the damage done to relations with other centre-right parties by the Tories leaving the European People's Party (EPP) may be a significant obstacle.
Trouble on the right
The Conservatives have good policies on the low-carbon transition. Yet I know from my own experience that it is considerably less difficult to adopt good policies in opposition than it is to achieve good outcomes in government.
From 1992-94, I was adviser to the then shadow environment secretary, Chris Smith, and secretary of the Labour policy commission on the environment. This produced In Trust for Tomorrow, which proposed targets to reduce carbon dioxide emissions by 20 per cent by 2010 and to generate 10 per cent of electricity from renewables in 2010. Smith negotiated the considerable internal discussion about this with skill and determination.
Then, from 1997-99, I was adviser to the environment minister, Michael Meacher. He and John Prescott played an important role in the Kyoto negotiations and tried hard to make our economy less climate-damaging. The changes in performance since 1997, however, have been very disappointing. The UK will meet its Kyoto target, due largely to the "dash for gas" that Labour inherited from the Tories. In office, ministers have had to deal not only with Labour Party politics, but also with interdepartmental Whitehall politics. Too often, these have proved insuperable barriers. The 2010 targets for carbon dioxide and renewables will both be missed. The UK gets a lower proportion of its energy from renewables than any EU country except Luxembourg and Malta.
I am no longer a member of a political party, and so do not have inside knowledge of politics today. But it is worrying that Tory ministers trying to implement their climate plans would have to deal not only with internal party and Whitehall politics, but also with difficult relations with other centre-right parties. Cameron, William Hague and George Osborne have all said that the EU should focus on global issues such as climate change. Yet, by leaving the EPP, the Tories have made it more difficult for the party to achieve this. For instance, a central part of developing clean energy sources is to get the EU emissions trading scheme working better. The scheme has had little impact so far because the price of carbon is unpredictable and too low; the best way to improve it would be to set a floor price. This could be done formally through the EU, but that would take many years. It could be created instead through a bilateral deal between the UK and German governments, which have enough allowances in effect to guarantee a floor price. But the Tories have reduced their influence with Angela Merkel's Christian Democratic Union.
The Conservatives accept that climate protection cannot be left to the market. They have called for an Emissions Performance Standard (EPS) to set a maximum pollution level from any power plant. This was an excellent proposal, as Ed Miliband, the Climate Change Secretary, recognised when he said that an EPS could act as a "safety net" in case CCS is not as effective as hoped. The UK could introduce an EPS on its own, but it would be much more effective if introduced across the EU.
Let us not lose faith
The EU's target to improve energy efficiency by 20 per cent by 2020 is merely an aspiration at present. The Commission is now saying that the target should be made binding, with predictable hostility from national governments. Allowing decisions to be made by the right tier of government is important, but not as important as taking the right decisions.
However, one way to get one tier to do certain things is to get another tier firmly committed. If Copenhagen and the follow-up negotiations in 2010 can secure legally binding commitments, it will concentrate minds. Several EU governments have been more willing to accept EU directives because they have a legally binding Kyoto target. The EU itself has said that if there were a strong international agreement, its reduction target would be 30 per cent, not 20.
So let us not lose faith entirely in Copenhagen. It is good that Gordon Brown and other world leaders are going to the summit (although, for Brown to be credible, he must put serious money into the low-carbon transition in the pre-Budget report). The real challenge, however, will come after Copenhagen. For it to be met, whoever forms the next UK government must engage extensively, seriously and constructively with Europe.
Stephen Tindale is a climate and energy consultant and co-founder of Climate Answers 
Take a walk on the dark side
In June, David Cameron pulled his party out of the centre-right European People's Party (EPP). He has argued that leaving the EPP will be good for European democracy, but the Tories' departure has distanced them from old conservative allies in Europe. In 2006, Cameron signed a joint declaration to form a new partnership, the European Conservatives and Reformists Group (ECR), chaired by Michal Kaminski.
The Conservative leader has pointed to the ECR's anti-federalist stance in attempting to justify his party's new alliance in the European Parliament, but among the politicians in the group are some who hold sexist, homophobic and racist views. Kaminski has come under scrutiny in recent months for his previous membership of the National Revival of Poland party, which has been accused of neo-Nazism.
The Tories may now lose influence in Europe in important settings such as the environment, public health and food safety committee (vice-chaired by Boguslaw Sonik, a member of the EPP), the committee on industry, research and energy, chaired by an EPP member, and the economic and monetary affairs committee, which has two EPP vice-chairmen.
The Conservatives are the largest party in the new parliamentary grouping, making up 25 of the ECR's 54 members. Its two other main partners are Poland's Law and Justice party and the Czech Republic's Civic Democratic Party.