As you might expect, the UN Climate Change Conference in Paris, which reached an agreement yesterday to limit the rise in global temperature to less than 2C, has been an international festival of hot air.

The bland, suburban conference centre hosting the two weeks of talks is populated by oversized animal cut-outs – a blue giraffe, a red camel – that we attendees use as landmarks to find our way around.

You hear people shouting into their phone, ‘I’m waiting by the pink kangaroo!’ But the outwardly cheerful menagerie is actually a Noah’s Ark installation designed to remind delegates of the perils of inaction. Woe to the pink kangaroo if the delegates fail to halt global warming.

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The French foreign minister, pictured waving, revealed the 'historic' legally binding agreement, which aims to limit global temperature rises, to more than 190 officials in Paris

Even the ‘welcome bags’ are worthy, made out of politically correct recycled cloth.

Our French hosts are quick to point out that their government will purchase ‘carbon offsets’ – somewhere a lot of trees will be planted – to balance the environmental damage caused by this massive talkfest.

Within limits, of course. Though there are an astonishing 40,000 people here (30,000 more than recent conferences), the French will ‘offset’ the emissions of just 22,000 official delegates. The other 18,000 should presumably plant their own trees.

The first two days belonged to politicians, and were dominated by lofty rhetoric. Nearly 150 world leaders gathered, delivering speeches that were fairly interchangeable: there was much talk of ‘ambition’ and ‘the next generation’.

Zimbabwe’s Robert Mugabe stood out, lambasting the West for causing global warming, and declaring that Africa would not cut its carbon emissions.

The final draft of the world's first comprehensive climate agreement has been announced after two weeks of fraught debates. Above, Greenpeace protesters tried to draw a yellow sun around the Arc de Triomphe during the talks

Then, soundbites duly issued, the leaders jetted home, leaving hundreds of national delegates bustling from meeting to press conference to side event, and activists exhorting them via press releases to commit to ever-bigger carbon cuts.

Yet after two weeks of negotiations about rising temperatures, the main thing that has risen is expectations. When a deal couldn’t be reached, the conference was extended into ‘extra time’. Delegates talked around the clock, agreeing the fine print for an agreement that will commit the world to massive economic costs while doing very little for the environment.

In a peer-reviewed research paper based on pre-conference pledges, I measured the environmental impact of every nation fulfilling every carbon-cutting promise between 2016 and 2030. I found that the total temperature reduction will be just 0.048C by 2100.

Even if we assume that every one of these promises would not only be fulfilled but extended for another 70 years (and countries don’t just import more products from carbon polluting nations) then all the promises made in Paris will reduce temperature rises by 0.17C by 2100. This is very similar to a finding by scientists at the Massachusetts Institute for Technology.

Much higher figures have been bandied about by activists, delegates and even the United Nations’ global-warming body, the UNFCCC.

The problem is that such claims are based on a wholly unrealistic scenario where governments do little now, then embark on incredibly ambitious and unlikely climate change reduction policies after 2030.

This is vanishingly unlikely. The only global treaty to agree a cut in carbon emissions – the Kyoto Protocol – failed when it was never ratified by the US, and eventually abandoned by Canada, Russia and Japan. In the 1990s and early 2000s, we learned that the only surefire way to make substantial emissions cuts was to go through a major economic recession.

Activists dressed as polar bears in a bid to persuade officials they needed to take action over climate change

Emissions dropped precipitously when the Soviet Union collapsed, and again during the 2008 financial crisis. Understandably, this approach is not very popular with politicians or voters.

But still the politicians make lofty carbon-cutting promises. And what they don’t talk about is the cost. In Paris you won’t hear it mentioned that this is likely to be the most expensive treaty in the history of the world. If you try to cut carbon dioxide, even with an efficient carbon tax, you end up making cheap energy more expensive and this slows economic growth.

Energy-economic models, including the gold standard Stanford University Energy Modelling Forum, show the EU’s GDP will have grown 1.6 per cent less by 2030.

Dishing out solar panels is feeble - even immoral

That means the Paris agreement will cost Europe £200 billion in lost GDP every year by 2030 – and this is if the EU enacts its regulations most efficiently. Otherwise the cost could double to £400 billion a year. For the United Kingdom, that could mean £50 billion lost every year. And for the world, this bill could run from £600 billion to £1.2 trillion per year.

Why so expensive? Because current green technology is inefficient. If it were economically advantageous to dump fossil fuels, why would we need to sign a treaty? Every right-thinking nation on the planet would stampede to cut CO2.

There has been much focus in Paris on the £65 billion committed to ‘climate aid’. This includes £4 billion from the UK. Much of that money – including the UK’s portion – is coming from cash intended for global development. Yet climate aid is a feeble response to global challenges.

Concerned about agriculture? Then invest directly in agricultural research and better farming technologies, not subsidising inefficient wind turbines.

Worried about ‘extreme weather’ events? These hit the poor the hardest: helping people out of poverty is a thousand times more effective than relying on carbon cuts.

Nor is climate aid what the world’s poor want. A global poll of 9.7 million people shows that the citizens of the world’s poorest countries say climate action is their lowest policy priority, behind education, healthcare, jobs and governmental reform.

When two billion people suffer from some form of malnourishment, and it is an underlying cause of death of 2.6 million children each year, 1.2 billion people live in extreme poverty, and 2.4 billion lack clean drinking water and sanitation, then dishing out solar panels is a feeble – and even immoral – response.

We can help them better, cheaper and more effectively.

The final draft of the world's first comprehensive climate agreement has been announced by French foreign minister Laurent Fabius (right) and French President Francois Hollande (centre) following two weeks of fraught debates

Two banners read 'Stop Climate Crimes' and 'Debout et Determines pour le Climat', meaning Raised and involved for Climate, are pictured as thousands of people demonstrate in front of the Eiffel Tower for climate change in Paris

However there has been some good news from Paris – and it has nothing to do with the agreement. It’s something that was announced on the sidelines on the first day, when Microsoft founder Bill Gates, other wealthy individuals and about 20 governments revealed that they will double green energy research and development.

This could put us on a pathway towards finally solving global warming. A huge increase in spending on research and development is the most efficient way to find new breakthrough energy technologies cheaper than fossil fuels.