Global warming: fact or myth?

Fact, says Phil Ineson, Professor of global change ecology at the University of York.

EACH year we seem to break more rec-ords for "the hottest summer", the "wettest day", the "warmest night".

Are we really living through a critical man-induced change in climate? Is this all part of a natural cycle, or are we sim-ply just better informed?

The confusion is not helped by opposing groups of scientists telling us, on one hand, that climate change is a normal part of our planet's behaviour, while others frighten us with tales of human-induced accelerated release of greenhouse gases, resulting in unpar-alled and runaway climate change.

Potential consequences of climate change are of such importance that governments world-wide have brought together a large international group of scientists to consider the available evidence and provide an impartial consensus of opinion. This group of experts is called the Inter-governmental Panel On Climate Change (the IPCC) whose job has been to sift through the thousands of pages of scientific evidence from around the world. The IPCC chairman has summarised these findings quite simply: "the overwhelming majority of scientific experts, while recognising that scientific uncertainties exist, nonetheless believe that human-induced climate change is already occurring".

So, while I welcome the individual voices which offer alternative assessments, and emphasise the 'uncertainties' which the scientists clearly have, I have read the IPCC evidence and I know where I place my trust. Brushing aside the conclusions of the IPCC is the environmental equivalent of ignoring advice from your doctor - unfortunately it is a bitter pill, but one which really needs to be swallowed.

Important pieces of information about past climate are gained, for example, from the detailed examination of air trapped in ice cores, drilled from up to three kilometres below the current Antarctic ice surface. Data from these cores tell us the carbon dioxide (CO2) concentrations in the atmosphere have been fairly consistent over a 400,000 year period, steadily cycling between 200 and 300 ppm (parts per million), with the time between peaks of about 40,000 years.

One of the most astonishing revelations from these cores is the incredibly tight link between these atmospheric CO2 concentrations and air temperatures; as the CO2 rises and falls, so does the temperature.

Alarmingly, the ice cores also show us that we have done something to the at-mospheric concentrations of CO2 unprecedented over the last 400,000 years, in that we have pushed the CO2 concentrations to over 360 ppm, and show no signs of slowing down. Unfortunately, the temperature also seems to be following.

What does this mean for Yorkshire and Humberside? A recent detailed local study on the likely extent and impacts of climate change has told us to expect warmer temperatures all year round, with an increase in annual temperatures of a few degrees C. This will be accompanied by a redistribution of rainfall. There will be the same overall annual volume of rainfall, but rain can be expected in shorter, sharper bursts with greater extremes of flooding and droughts. Very cold winters, with extensive snow falls, will become a thing of the past.

Whether we like it or not, climate change will affect human activity around the globe and while the local impacts of flooding in Yorkshire may range personally from the mildly inconvenient through to a major disruption, it is worth noting one other IPCC conclusion.

The impacts of climate change will actually fall disproportionately on the developing countries, where there are limited resources to deal with the prob-lems. So I think the science is quite clear; the really cloudy areas are the political and social responses.

Myth, says naturalist Professor David Bellamy.

I first became sceptical about the latest bout of so-called global warming being due to a rise of the levels of carbon dioxide when I took a look at the facts and figures of past climate change recorded in scientific texts and papers.

The glaciers of the last ice age began to melt in earnest about 15,000 years ago, thanks to completely natural causes.

Since then evidence from pollen and ice cores and from history tell us that our temperate climate has been far from temperature stable over a range of some six degrees Celsius. Stone Age cultures adapted to many fluctuations, the Romans grew grapes in York, Canute used fossil fuel to help combat the little ice age, and Pepys complained about hurricane force winds and wrote about ox roasts on the frozen Thames.

Remember the balmy days of the forties and then that awful winter?

Now a mere 50 years on the vagaries of climate change are hitting the headlines as man made. Complex models put the blame mainly on the release of carbon dioxide, with dire warnings of Armageddon around the corner.

Yet anyone who walks the dog on a winter's night knows that clouds trap the heat of the day, holding it in the atmospheric blanket.

Science tells us that water vapour is the most important controller of our temperature making up some 96 per cent of all the greenhouse gases.

If we took all the water vapour out of the atmosphere the temperature would plummet by 33 degrees Celsius.

If we took all the carbon dioxide out of the atmosphere the temperature would drop very little.

For the simple reason that compared to water vapour there really isn't that much up there to trap the energy of the sun.

Mind you we wouldn't be around to record the fact because without this very important gas, photosynthesis just couldn't happen.

Yet institutes to study climate change were set up and the whole Kyoto protocol was swung into action, laying the blame firmly on rising levels of atmospheric carbon dioxide. It is a basic fact of physiology that if the temperature goes up living things produce more carbon dioxide.

I wait to see results from ice cores that prove that the opposite has happened since the last glaciation.

As total cessation of man-made CO2 emission is impossible and as the atmosphere and ocean-surface reservoir contains several hundred times as much CO2 as the annual fossil fuel input it is laughable to expect that our government's targets, especially as they are based on intermittent wind, can make a measurable difference, let alone alter climatic trends. Even if every country of the world aimed for a similar ten per cent target the total shift of concentration would still be too small to have significant effect.

If the modelers are right we are in a catch 22 situation and if they are wrong, think of all the better things we could do with the money that would be spent on implementing Kyoto.

Fortunately, there is a half way house that could begin to meet all objectives very quickly, energy efficiency, that would save our dwindling fossil fuels and give us time to find efficient alternatives with which to fuel our changeable future.

Tidal power is there for the taking around the clock and wave power and solar, though intermittent, could help fuel a hydrogen economy.

I am still a scientist and an optimist.

Updated: 09:34 Thursday, August 12, 2004