22 july 2011

The art and the science of climate change

Speech by Secretary of State for Energy and Climate Change, Chris Huhne. UK Government website, 21 July 2011

I am delighted to be here today, and to give the last of a series of three speeches about climate change.

Three weeks ago, I spoke about the economics of climate change. The case for green growth.

Two weeks ago, I spoke about the geopolitics of climate change. About how it threatens our security in ways we haven’t yet grasped.

Today, I will talk about the science of climate change, and what it tells us about the timetable we have.

And the global negotiations, and how long it will take to reach an agreement. It is the tale of two timetables: the scientific, and the political.

But first, let us remember how we got here.

The basics

Nearly two centuries ago, a French mathematician and physicist named Joseph Fourier wondered why the Earth was warm enough to support life.

We are the best part of 100 million miles away from the sun. The planet ought to be much colder.

Fourier considered a new possibility: that the atmosphere that we breathe also traps heat. In 1827, he described the greenhouse effect.

Let me put that into perspective. Our understanding of the greenhouse effect has been around longer than the periodic table. It predates the study of genetics and the theory of evolution.

It not only well-understood – it essential to life. Energy from the sun passes through the atmosphere and warms the earth. The earth radiates heat, which is absorbed by the trace gases in the atmosphere. The warming is fed back, and amplified. Without it, our planet would be some 33 degrees colder.

Over millennia, global temperatures and weather patterns vary. A natural equilibrium keeps it all in balance. Given enough time, Nature is largely self-correcting.


But since Fourier made his discovery, things have changed.

Much of the planet has industrialised. Its population has soared. We have moved from small scale agriculture to large scale industry. We have swapped horses for horsepower. And we are emitting more greenhouse gas than ever before.

The amount of carbon dioxide in our atmosphere is rising. Concentrations of CO2 have grown by 40% since pre-industrial times. Two thirds of that increase has happened in the last 50 years.

With all this extra greenhouse gas floating about, we would expect the Earth’s surface to get warmer. And so it has: by about 0.8 degrees in the last century.

Much of this warming has occurred in the last 50 years. From 1960, temperatures have risen at an average rate of 0.13 degrees per decade. The ten warmest years on record were all from 1998 onwards.

So the basic science is clear. It tells us these three things: greenhouse gases warm the planet. Global emissions continue to climb. And the world is warming up.

It is a compelling picture, and one supported by a growing body of evidence.

Arctic sea ice is melting. Since 1900, global sea levels have risen by more than eight inches.

Severe droughts are now twice as common as they were in 1970.
Research suggests human action doubled the risk of the 2003 European heatwave.

And climate change made the autumn 2000 floods in the UK about twice as likely.

Every major scientific institution in the world concurs: the Royal Society, the US National Academy of Sciences, the Academie des sciences. Change on this scale cannot be explained by anything else.

There is no computer model of world temperature and climate that can explain what has happened without greenhouse-gas induced global warming. None.

Unless we act to curb greenhouse gas emissions, continued warming is not a matter of speculation. It is inevitable. And scientists fear it will accelerate.


As temperatures rise, so does the risk of crossing dangerous thresholds in the climate system – leading to sudden, irreversible change.

The Amazon rainforest holds about 10% of all the carbon stored in ecosystems. If it dries out, scientists fear it could release more carbon than it absorbs. Warmer temperatures and more frequent droughts would kill more trees, releasing more carbon.

Arctic ice helps to regulate global temperature by reflecting sunlight back into space.

As it melts, it exposes dark ocean beneath, which absorbs more heat, melting more ice and amplifying the warming.

The dangers

We cannot risk setting off these climate chain reactions. Let us be clear: the kind of world where global warming hits three or four degrees is not the kind of world we want to live in.

It is not about sunbathing in the Scottish Highlands. It will likely be a nastier, more brutal world. Climate change above 2 degrees is called catastrophic for a reason.

Warmer air carries more water. Humidity means storms, hurricanes, flash floods.

Understanding these risks means setting aside ideology and being clear-eyed about the dangers. Forget the political posturing, and listen to the people who are paid to think about risk.

In 2009, the Association of British Insurers said – and I quote – ‘our assessment of climate change convinces us that the threat is real and is with us now’.

Last month, more than 70 European companies, including Ikea and Coca Cola, asked the European Union to aim for more ambitious carbon cuts.

Scientists tell us we must act. Businesses tell us we must act. Even militaries tell us we must act. We have a democratic responsibility to answer the call.

Government governs with the consent of the people. That consent is given only in exchange for basic assurances: that government will provide and protect. Climate change threatens our ability to do both.

Government cannot sit idle. If it were any other threat to our very existence, we would act.

We would not shirk from our duty to provide our people with clean water, or enough food, or protection from invasion. A stable climate is no different.

The deadline

Luckily, there is a growing political consensus, as we saw in Cancun; and a plan. We need to keep global warming to within 2 degrees of pre-industrial levels to avoid the worst effects of climate change.

That doesn’t sound ambitious. The kind of timescales used in climate science - looking ahead to 2050, or back to the 19th century - can give the impression that this is all quite distant.

Nothing could be further from the truth. Unfortunately, in our complex climate system, there is a delayed reaction between emissions and warming.

We could turn off the engine today, but the flywheel is still spinning. It will not come to rest for some time.

Temperatures have risen by 0.8 degrees already. Even if we completely stopped all emissions, today, they would still rise by about half a degree.

That takes us more than halfway toward our limit. Next time someone mentions the 2 degree limit, remember that we are already 1.3 degrees along the way.

So this is not an abstract discussion. There will come a time when it is too late to turn this thing around. That time is rapidly approaching.

If we do nothing now, it will cost us more to do something later – environmentally, economically, and politically.

Sticking to our 2 degree limit means global emissions must peak by 2020 at the latest.

To avoid radical upheaval, we need to shift the world economy onto a low-carbon path by the middle of the decade.

What does this mean?

This Parliament will end in 2015. If we have not achieved a global deal by then, we will struggle to peak emissions by 2020. It will be more expensive, more divisive, and more difficult.
This is the last Parliament with a chance to avoid catastrophic climate change.

The gap

The good news is that we have already started.

Every major economy in the world has targets that will curb carbon emissions.

The US plans to cut its emissions by 17%. China wants to reduce the carbon intensity of its economy by between 40 and 45%. Brazil has targets to reduce its emissions by at least a third below projected levels.

These countries – along with all major economies – are making progress on the practical programmes to deliver their commitments.

The bad news is that - although it is significant – it is not enough. We have rather a long way to go. Current global pledges will only get us halfway to a safer path.

If every pledge made at Copenhagen was implemented in full, we would still be some 5 Gigatonnes short of our target. To give you a sense of scale, that’s the equivalent of total global emissions from cars, trucks and buses in 2005.[1]

Over the next ten years, emissions must rise less than they did between 2009 and 2010.[2]

So there is a gap between the scientific reality and the political response. How can we close it?

Finding a fair and just answer to that question is the one of the sternest tests of diplomacy we have ever faced. Therein lies the art of international climate change: the co-operation and negotiation that will lead us to a safer, cleaner future.

The solution

We must do three things.

First, we need to walk the walk. We need to change the investment landscape, locking in low-carbon energy and infrastructure. That means demonstrating we can build a thriving low carbon economy here in the UK – and more widely in the EU.

It also means demonstrating the advantage of low-carbon growth. Not just in developed but also in developing countries, which can leapfrog our old technologies and take advantage of new ones.

The best way to get electricity to a village in India might not be to connect to an old grid, but with solar power and decentralised storage. We must show that the pathway to prosperity for all the world’s people does not lie with pollution.

Second, we need to rebuild public and political support for action at home and abroad.

That means using soft diplomacy to shift the politics and build coalitions. Explaining the case for action not just on environmental grounds, but on economic and security grounds as well. Using targeted financial and practical support to help developing countries build cleaner, more climate resilient economies.

And third, we need to come together to forge a new agreement on global emissions.

That means further developing the global legal framework over the next few years. And working with major economies to build the political conditions that must be met before a deal can be signed.

These three tasks must be carried out with clarity of purpose and strength of ambition. We cannot afford to ignore any one approach, or favour another. We must pursue each with vigour.

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