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Jun 2nd 2010

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Climate change facts, uncertainties and actions

On Tuesday 26 May 2010, Lord May of Oxford gave a public lecture at the UTS School of the Built Environment. He outlined the science behind climate change, the UK response, and the international status quo after Copenhagen.

In the 150 years since Darwin’s Origin of Species, the world’s population has grown from less than one billion to almost seven billion people. The amount of energy required to support the daily activity of the average person – for food, transport, housing and so on – has also increased sevenfold.

The two combined mean that humanity’s total energy ‘footprint’ has increased more than fifty-fold – arguably beyond the limit of sustainability for the planet. Although there are variations between countries, the fact is that each year we burn about a million years’ worth of fossil fuel deposits, and it is beginning to affect the climate.

What we know (and don’t know) about the way we are changing the climate

The climate has undergone terrific changes over the five billion year history of planet earth – from snowball to tropical oven. Ice ages have come and gone even in the last 200,000 years.

But during the last 10,000 years (roughly since humanity began farming, built the first cities and started to increase in numbers), global temperature patterns have been relatively stable. There has been an atmospheric greenhouse gas (GHG) level of around 280 parts per million during this time, and scientists agree that this greenhouse gas ‘blanket’ is essential to maintain the temperature of the atmosphere.

Greenhouse gas levels in the atmosphere have increased sharply since the industrial revolution, accelerating through the last century to around 387-88ppm today – with no sign of slowing.

When concerns began about rising greenhouse gas levels, there was great uncertainty about the consequences. But as computing power has increased, we have been better able to model the effects of burning fossil fuels.

On the scale of tens of thousands of years we could expect global temperature swings due to factors other than greenhouse gases. Models suggest that, without fossil fuels, we might have seen the arctic cooling slightly in the next thousand years. However, we have seen it rise 0.7 degrees in the last century. By today, you cannot explain what we are seeing without recognising the effect of the thickening of the blanket.

Climate change sceptics are like people who say they don’t believe in tides because you can’t say when the next wave is coming. You have to distinguish sustained long-term trends from daily and seasonal fluctuations.

At the G8 summit in 2005, world leaders acknowledged three things: climate change is real; it is largely caused by us; and it is serious.

UK Legislation and consequences

In 2006, the Nicholas Stern Review looked at the effects of climate change on the global economy. The Review estimated the costs of stabilising GHG levels at 500-550ppm would be between 5% cost (or perhaps 2% gain) of global GDP.

By contrast, the costs of doing nothing would be 5-20% of global GDP (on average). There would be some winners in climate change, but the losers would be primarily equatorial places – already the poorer places in the world. The thinking was that if we can keep temperature increase to less than two degrees, then the worst consequences can be avoided.

The British response was a 2007 climate change bill calling for:

  • legally binding targets;
  • a committee to oversee those targets; and
  • a framework for fiscal instruments to help.

In December 2008, the Committee on Climate Change ( produced its first report, calling for a global emissions reduction target of 50%. In order to stabilise atmospheric greenhouse gas levels, a global average of 2.5 tonnes per capita would be necessary.

To reach the 2.5 tonne average, the UK would have to reduce its present per capita emissions by 80% by 2050, which would still allow developing countries like India and China (currently both well under 2.5 tonnes per capita) to keep increasing.

The interim target is 34% by 2020, but with the desired target of 42% if a global deal is achieved.

The Stern Report acknowledged that if we do this and no one else does, we still inherit others’ messes. However, decisive, early action remains a good economic idea, providing energy security, water security and efficiencies that other countries will not have.

To date, the UK is one of the few countries to have actually reduced greenhouse gas emissions on 1990 levels, but there’s a long way to go.

Copenhagen and the Financial Crisis: good news and bad news

The bad news out of Copenhagen was that there was no ‘Kyoto 2’ agreement. However, there was some consensus:

  • Climate change is real
  • Global average temperature increases should be kept to 2°
  • The science demands deep cuts in global emissions
  • It is more efficient to do things early than late
  • We need a tough set of targets

Leaders agreed that, to reach a global average, developed countries must move down to it, while developing can move up. Developing countries agreed to commit to targets, self-measured, but reported, and developed countries commited to providing resources and technology to help them achieve their targets.

During the Financial Crisis, many economic stimulus packages had green measures. There have been hiccups – a recent Utah bill in the US that said that there is no such thing as climate change, for example – but most countries are acknowledging the problem, and making gestures towards doing something about it.

The UK is one of the only places which has managed to reduce its carbon emissions in the last fifteen years. In all, what is important is how soon – earlier actions will have disproportionately large effects.

Climate change is real, and has serious implications for biological diversity, water scarcity, food security, hunger, coastal risk, and crop decline. Although we don’t yet know all the consequences, we do know that equatorial and developing countries will bear the brunt.

The hard sciences are rigorous. They are relatively easy. In some ways, the most important sciences are the social sciences that ask ‘how do you motivate people to do something?’

Lord May’s lecture was jointly presented by the UTS School of the Built Environment, Faculty of Design, Architecture and Building, and the Australian Institute of Building, with support from the APCCRPR and BEDM.


  1. Mike Flynn says:
    AGW is caused by heat, not CO2. Measuring CO2 levels is fairly pointless. Consider a submerged nuclear submarine warming the ocean with its waste heat, and hence contributing to AGW. Now go a step further. Replace all fossil fuel generated heat (including waste heat, with non carbon based heat - nuclear, hydro whatever. Same heat, no increase in CO2. Your blanket analogy is accurate, but the blanket of the atmosphere acts to slow, not trap, outgoing LWIR. Exactly as any other low value insulator would. And in fact, acts both ways. It slows the heating caused by insolation. Removing CO2 (an essential part of life on Earth) would make as much difference as replacing 400 parts per million of your blanket with a different fibre. Maybe this makes sense to you. I obviously just don't "get it".
  2. Eric Crane says:
    A natural system known as the "greenhouse effect" regulates temperature on Earth. Just as glass in a greenhouse keeps heat in, our atmosphere traps the sun’s heat near earth’s surface, primarily through heat-trapping properties of certain “greenhouse gases”. Earth is heated by sunlight. Most of the sun's energy passes through the atmosphere, to warm the earth's surface, oceans and atmosphere. However, in order to keep the atmosphere's energy budget in balance, the warmed earth also emits heat energy back to space as infrared radiation. As this energy radiates upward, most is absorbed by clouds and molecules of greenhouse gases in the lower atmosphere. These re-radiate the energy in all directions, some back towards the surface and some upward, where other molecules higher up can absorb the energy again. This process of absorption and re-emission is repeated until, finally, the energy does escape from the atmosphere to space. However, because much of the energy has been recycled downward, surface temperatures become much warmer then if the greenhouse gases were absent from the atmosphere. This natural process is known as the greenhouse effect. Without greenhouse DUH! It`s not rocket science
  3. Eric Crane says:
    Without greenhouse gases, Earth's average temperature would be -19°C instead of +14°C, or 33°C colder. Over the past 10,000 years, the amount of greenhouse gases in our atmosphere has been relatively stable. Then a few centuries ago, their concentrations began to increase due to the increasing demand for energy caused by industrialization and rising populations, and due to changing land use and human settlement patterns. Sorry missed this bit on the end
  4. Fact: one does not fix the problem - overpopulation by treating the symptoms and hoping the root cause will go away. This month we made the fastest billion people ever. It took us just 12 years. By 2050 the US median forecast is for another 2 billion on top of that. If you think any of the measures introduced by government will have any effect in the face of a 50% increase in global population you need to come back from la-la land.
  5. Hmm is anyone else encountering problems with the pictures on this blog loading? I'm trying to figure out if its a problem on my end or if it's the blog. Any feed-back would be greatly appreciated.

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