climate change global warming

Debate: For and against climate change

Have scientists been responsible for exaggerating the extent to which human activity is affecting the global climate?

For: There is a conclusive body of evidence to support the existence of manmade climate change

By Peter Landon

Speaking as a palaeoclimatologist, reconstructing past climates, one of the key lines of evidence for human impact on climate change is that over the past few millennia we have never seen such a rate or magnitude of warming that we see now. Past climate tells us about trends and variations prior to human impact and when analysing these we never see a trajectory in temperature increases as we are seeing today.What the Intergovernmental Panel on Climate Change (IPCC) says is this: we have measured temperatures over a recent period, the past 150 years or so, on land, at sea and in particular the sea surface, which covers a large part of the planet.

Temperatures are rising and in the past few decades there has been unprecedented acceleration. We know that our production and burning of fossil fuels is rising. We can measure the chemical signature of the gases in the atmosphere, and they are not all natural. This is due to what we have burned and put into the atmosphere.

You can do a simple correlation to say that increased temperature and the presence of greenhouse gases are related. But obviously we have to deliver better science than that. One thing we can do is to look at the global climate computer models - and there are a lot of them - that represent our current understanding of how the climate works. If we run these models with what we call natural ‘forcings’ of climate - such as fluctuations in the strength of solar radiation over time - and compare them with what we have observed, then the two don’t fit. This is consistent across all the main global climate models.

There is more affecting the climate than natural forcings. This includes anthropogenic (i.e. human-induced) gases. The second thing you can do is to run the effect of these global-warming gases against what we have observed. And they don’t fit either. But, when you run the natural forcings and the anthropogenic gases together, they fit. The conclusion - and the IPCC says that this is extremely likely - is that the warming, especially in the past half-century, can’t be explained without the anthropogenic greenhouse gases.

This finding is one of the most amazing things we’ve done as scientists. We have gathered from all the major countries in the world people who are interested in understanding how climate change works and actually got them working together under the auspices of the IPCC. I can’t think of many other programmes where you have such a community of serious scientists collaborating on a global project pulling together. The majority of their data and modelling scenarios are in the public domain and it is all saying the same thing. To go against this with no evidence seems to lack an understanding of what science is for.

What’s next? As a scientist you typically collect the evidence and present it to policy makers. That is one of the tricky bridges that needs to be built. You need better dialogue with and influence over policy makers. But it seems to me that when the scientific evidence is so compelling to not do anything is very odd.

Even looking at the more moderate long-term projections of climate change you would have thought that curbing fossil fuel consumption has to be the way to go. But you could argue that economic power is the greatest power, and so unless you can cross the short-term economic argument things will get difficult.

The most important thing is that America and China come on board. If the greatest per capita emitters of greenhouse gases do not buy into the scientific findings then the future looks pretty grim. In 100 years’ time we will look back and think: “what on earth were we doing burning all that stuff, when the evidence was so overwhelming and when we had the opportunity to do something?” Ultimately, we’ll be judged by history and today we are simply not in a position to be judged favorably.

Against: There is no conclusive body of evidence to support the existence of manmade climate change

By Johnny Ball

When the climate-change furore began around 1988, I was alarmed and took a stance against it, earning the title ‘denier’. Now, 24 years later, everything I advocated then has been proven to be true. The damage done to the image of science, engineering and technology in terms of warping the minds of future generations of engineers and scientists, politicians and the general public will take years to repair. So on what did I base my opposition, with complete disregard to the danger to my reputation? Was the planet warming? Yes, it was, and by 1998 it had warmed 0.7°C in 100 years. But it had reached that peak in the 1930s and had been so much cooler in the 1960s as to suggest an oncoming ice age. There was, and still is, nothing alarming about the trend at all.

But the Intergovernmental Panel on Climate Change (IPCC) consistently claimed that catastrophic changes were taking place. We now know that all those claims were exaggerations and their leader Rajenda Pachauri has said: “There must be no more exaggeration!” In truth, there has been no sea-level rise, glacier depletion, ocean acidification or polar ice loss. All have fluctuated in line with normal expectations.

Burn anything, including food, and hydrocarbons split with oxygen to produce CO2 and water with usually two molecules of water for every one of CO2. Now the water is a greenhouse gas. Cloud traps heat and keeps things mild, while the absence of cloud lets heat disappear and we have morning frost. In fact, water is more than 85 per cent of the cause of local climate-change. But the IPCC never introduced water to the computer models that pointed the finger at CO2.

The major thrust of climate-change claims is that man is destroying the planet. There is much evidence to show that we are the greatest burden that Earth has to bear. To simply rape the earth of all its fossil-fuels would be gross folly.

But there is a conceit that mankind is so important. Less than 4 per cent of all CO2 produced is manmade. Every tree and creature grows, dies, rots and ferments, giving back its CO2. The oceans covering 70 per cent of the Earth’s surface contain 80 per cent of all plant and animal life. Man, compared to that, is far less significant. Only one-quarter of the 30 per cent of the planet that is land can support man unaided - just 7.5 per cent of the entire surface. Add volcanoes and natural phenomena, and man is quite puny. But we are a burden to the Earth and reducing that burden is our responsibility. The answer is engineering greater efficiency.

But look at our record in that. The Clean Air Act of the late 1950s means that today a building stays the same colour as when new. The catalytic converter means that vehicles are cleaner than even thought possible 25 years ago. It prevents sulphurs entering the atmosphere and turns unburnt or half-burnt carbons into CO2. Why? Because CO2 is harmless. More CO2 provides more plant food and is, in effect, greening the planet.

New cars require only half the engine size to produce the same power and twice the mileage. Electric generators that 25 years ago were around 30 per cent efficient are now around 70 per cent efficient. Yet the ‘greens’ would have us adopt wind generation, solar power or electric cars, none of which can ever approach the efficiency of boiling water to achieve a 600 times expansion and thus power the world as economically as is possible to date. Green policies cause more damage.

Whatever our future problems, including unburdening the planet, engineering is our only salvation, and improvements are huge in every aspect. Recent miracles will be dwarfed by those we will achieve in the future. But only if we put our faith in leading-edge engineers finding the best and safest way forward.

The day of the extreme, irrational, badly schooled yet powerful environmental lobbyists must come to a close, for all our sakes.

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