Lectures & Talks
Climate Change: where we are now?
By Dr Michael Shallis; a talk given at Chisholme in July 2007.
This talk gives a brief introduction to the current state of climate change research. It explains what climate is, and what affects it. The talk then considers CO2, what it is, why it affects climate, and in what way human activity can become a factor in climate change.
The key concept that has emerged from the last hundred years of science is that reality is one. There is one universe. This concept is evident in every aspect of nature that scientists have looked at, even though the "scientific method" is often reductionist in manner. But in branch after branch of the sciences what emerges is that all phenomena are interconnected, interpenetrated, inseparable.
In quantum physics and cosmology the picture that has emerged is one in which all parts of the universe are interconnected and interdependent. At the smallest scale of sub-atomic physics particles affect each other acausally across time and space. Energy interactions are only isolated in thought. What happens here affects the whole, what happens now affects all times. What the physics shows us is that there is only one energy.
Similarly in the life sciences. Advances in genetics over the recent years has shown us that our genetic make up is both unique and shared with every other living thing. Life, too, is one.
Over the last fifty years great advances have been made into an understanding of the earth's climate and here, too, we find the same kinds of interpenetration of phenomena, of the interdependency of any one factor or event on all other factors and events. The planet, Gaia as James Lovelock described it, is one. Its climate is one and there is nothing that is done on earth that does not affect the whole planet.
The climate is what happens in the earth's thin atmosphere and at the interface the atmosphere has with the land mass, the oceans and with plants, animals and people. Locally we call the climate weather. If the earth was a six foot ball the atmosphere would be the thickness of a coat of paint. What the climate does is distribute energy around the planet. The energy comes from the sun and more of it is received at the equator than at the poles. That energy is absorbed or reflected in different degrees according to the type of surface encountered. Water absorbs energy but reflects it when frozen. Desert sand or rock reflects energy back into space, vegetation absorbs it. The climate moves energy about in order to find an equilibrium and it is always in flux. It is measured as temperature, pressure, wind speed, humidity, precipitation and composition. Global warming means there is more energy in the atmosphere and hence atmospheric events, such as storms, are themselves more energetic. The system is always trying to find a balance.
This is a natural process and often a very subtle one. The interaction between atmosphere and ocean surface is one of constant movement, with molecules from the air being absorbed by the water and released from the water, forever adjusting to the ambient temperature, wind and wave and so on. Similarly with the interactions between atmosphere and vegetation. Plants absorb CO2 and use the carbon for growth, releasing the oxygen into the air and returning the carbon to the atmosphere only when they decay. Indeed the evolution of life on earth came about through this mechanism, converting a CO2 rich atmosphere into an oxygen rich one, suitable for the development of animal life.
Climate changes. It is changing now, only this time the changes are different, they are induced by the action of man.
Over the last few million years there has been a marked cycle of climate change – the cooler ice ages interleaved with warmer interglacial periods. One of the changes that occurs during this cycle is the concentration of CO2 in the atmosphere. Carbon dioxide is one of the main "greenhouse gases", so called because their presence has a warming effect, trapping heat energy within the atmosphere. CO2 is absorbed by vegetation, by the soil and by the ocean. It dissolves in water (hence fizzy drinks) and is also stored in the seas in plankton and other marine life. The ability of the ocean to store CO2 is dependent on temperature; during an ice age far more is stored in the seas than in an interglacial period.
The simplest description of the amount of CO2 involved in this process is by looking at the total mass of carbon dioxide in the atmosphere. During an interglacial period (such as we have had throughout historical times) the amount of CO2 in the atmosphere is 600 billion tons. During an ice age this figure reduces to 400 billion tons. The difference (200 billion tons) became stored in sea, soil and vegetation and was released again as the climate warmed.
In the evolutionary history of our planet part of the mechanism for giving us an oxygen rich atmosphere, which can support life forms, was the locking away of excess carbon over a period of millions of years. Vegetation became fossilised and, after geological processing, became fossil fuels, coal and oil. They were vast carbon sinks.
What has happened in the age of industrial man, and most particularly over the last hundred years, the oil age, is that we have released a lot of that stored carbon back into the atmosphere by burning fossil fuels. The amount we have released so far is another 200 billion tons. The atmosphere today holds an unprecedented 800 billion tons of CO2 and this causes the planet to warm.
But this figure is not static. Man's activity is adding another 7 billion tons of carbon dioxide to the air every year. So the figure for 2007 is 810 billion tons. It is known that a concentration of CO2 of 850 billion tons produces a heating effect that raises average worldwide temperatures by 2 degrees C. At present rates of pollution that figure will be reached within 10 years. A rise of 3 degrees would make our climate as different from the norm as the difference between an ice age and a non-ice age. A rise of 6 degrees would make most life untenable. The margins are surprisingly small and finely tuned.
Governments have more or less agreed that a 2 degree rise in temperature could be managed and they look to stabilise our emissions to that figure. Many argue for a higher figure, but time scales are surprisingly short, especially when it is noted that every prediction so far has been too conservative. Global warming is taking place much quicker than anyone expected.
Returning to the 7 billion tons of CO2 we put into the atmosphere every year, about 3 billion tons is mopped up by the natural mechanisms of absorption by vegetation, soil and sea. However, it is now becoming clear that these mechanisms are at, or close to, saturation point and becoming less able to cope; we are polluting at a rate that nature cannot deal with except through temperature rise. So the 3 billion tons nature has been mopping up is reducing, and reducing year on year. We have pushed the climate to its limit.
Two examples of this are seen in research results recently published. In 2005 extensive studies right across the UK showed that our soils have stopped absorbing carbon dioxide, turning from being a sink of CO2 to being a source. British soils are now emitting more greenhouse gases than our industry is cutting back on.
In the last month (May 2007) it has been shown that the Southern Ocean has now reached its limit of CO2 absorption. That vast ocean is at saturation point. Both of these examples point to the situation where the effects of global warming will accelerate and that is already showing up. What we are seeing now has been moderated over time by the fact that the oceans warm up more slowly than the land. Just as in a house, where the boiler has to heat all the water in the radiators before the warmth fully comes through to the rooms, so too with the oceans. The findings in the Southern Ocean indicate that we are reaching the point where the water is becoming warm. The process has quite a long lag time (maybe 30 years) so if we could "turn off the boiler" now, it would be a generation before the effects were seen.
What is the "boiler"? The answer is simple, man made emissions from burning fossil fuels. These emissions are forcing nature"s response, which is climate change.
The earth and its climate is one system. What happens here and now affects the whole. Man is not separate from nature and man's actions, whether for good or ill, affect the whole planet. Understanding what is happening in the context of the awareness of this interdependence is surely where we start facing what climate change means.
Climate Change: update
Since writing the article Climate Change: where we are now back in June 2007 four developments have taken place that illustrate how quickly things are changing.
The Intergovernmental Panel on Climate Change (IPCC) have published their fourth report, laying out the science that leads them to the conclusion that climate change is due to mankind’s polluting emissions and that there is not much time in which to bring those emissions under control or face the consequences of runaway climate change. The Panel base their work on what can be called the standard model of how the climate works. The standard model is conservative and does not take into consideration, for example, the accelerating ice melts in the polar and glaciated regions. It is being updated continually in the light of new research. However its time scales appear to be too generous, as we shall see.
At the time of writing this update the negotiating teams from virtually every country on the planet have gathered in Bali to thrash out the treaty proposals for emission control post Kyoto, to come into effect in 2012. These teams are being told of the latest research findings.
One piece of work relates to the boreal forests of the northern hemisphere, the vast tracts of forest that stretch from Siberia across Russia and eastern Europe and across North America mainly in Canada. These forests are vitally important as sinks of carbon dioxide but the latest findings show that, although deforestation is not destroying these forests, changed climate, especially drought, is leading to wild fires that put more carbon into the atmosphere than the forests mop up. To lose this carbon sink is of great concern.
The results from a twenty year research programme into the state of the North Atlantic has shown that this ocean, like the Southern Ocean, is at saturation point with respect to carbon dioxide. This is mainly due to increased water temperature. The standard climate model predicts that this would not be expected until 2050.
The final piece of recently published research has shown that the tropics are spreading north and south at a sufficient rate to be easily measured, bringing more and more land into the arid belt, with serious consequences for agriculture and human societies. This result was not predicted by the standard model until the year 2100.
The difficulty with prediction is that natural time lags between rising carbon emissions and the measurable effects of these is not clearly known. If the time lag is short (say five to ten years) then what we are seeing now would be the result of emissions in the late 1990s. If the time lag is much more (say thirty years) then we would be seeing the results of emissions in the 1970s and emissions since then have grown significantly. This would be a worst case scenario, with resulting climate change being quicker and more dramatic than the standard model predicts.
There is now barely a week goes by without extreme weather being reported in the main news media. A warmer atmosphere contains more energy and this is dissipated by storms, tornadoes and increased rainfall. This is expected. What is more of a surprise is that the rate at which glaciers are melting has doubled in the past four years.
In the second article on climate change we will look at what measures are needed to try to stabilise global warming and what the consequences are with respect to energy use.
Dr Michael Shallis, March 2008
Part 2, The Energy Crisis, and Part 3, Sustainable Development, will follow soon.
Dr Michael Shallis
Dr Michael Shallis was University Lecturer in Physical Sciences at Oxford University. He was research assistant in the Department of Astrophysics and later ran the science programme for the Department for Continuing Education for ten years. He wrote On Time, The Silicon Idol and The Electric Shock Book, together with chapters in other anthologies. He has followed the research into climate change since the early 1970s. Now retired, he lives in the Scottish Borders.