Global Warming: searching for common ground

The world seems to be sharply divided between those people who are convinced that global warming is a serious issue that is largely the result of human activity, and those who prefer to downplay its seriousness and deny that mankind is responsible for any global warming that may have been observed. But is there common ground from which any sensible debate can proceed?

A fractious debate

When the two sides in the global warming debate get to grips with each other the amount of such warming appears to be minor in comparison to the heat that is generated between the participants! It is not long before each side accuses the other of being biased, unscientific, or harbouring an agenda that goes far beyond the facts of the matter.

It would therefore surely be good to agree on some basic facts that are beyond dispute. Once these are agreed, it is possible to start arguing about their extent and significance, which is where the heat of debate is generated. This short article therefore seeks to do just that, with the implication that people can seek to agree or disagree with my contention that they are, as it were, beyond contention!

The world is getting warmer

The mean average temperature of Planet Earth can be taken in a number of ways, several of which can produce an historical timeline of temperature differences. One such record, gathered from surface temperature recordings (land and sea), is shown above. This was obtained from data produced by the World Meteorological Organization

This graph is surely unequivocal evidence of a steady rise in temperature between the years 1880 and 2020. As a starting point, is this not something that both sides can accept?

The effects of global warming are plainly visible

The most obvious signs of a generally warmer world include the melting of sea ice in the Arctic Ocean, the shrinking of glaciers in many parts of the world, and the loss of permafrost in Siberia. Evidence on such matters is gathered and presented by, for example, the National Snow and Ice Data Center.

The evidence concerning world weather patterns and the increasing frequency of extreme and violent weather events is more contentious, and so stays “off the table” at this stage.

The science is far from simple

Nobody should make the mistake of thinking that any of the science is straightforward, because it is not. Just as one swallow does not make a summer, one year’s anomalous figures prove nothing one way or the other.

Likewise, it must also be remembered that all sorts of factors are at play here, and sometimes they work against other to produce conflicting evidence. Climate science deals in trends, and sometimes it takes data from many sources and over a long span of time in order for such trends to be detected. This means that it is important to base one’s arguments on sound science that takes all the complexity into account and is also bound by the requirements of long-established scientific method.

The greenhouse effect

Certain gases in Earth’s atmosphere have the same effect as a pane of glass in a greenhouse, namely that they trap the heat produced by solar radiation and ensure that anything under the “glass” will be warmer than anything above. If this were not the case, life on Earth would be impossible.

The question remains as to what is desirable in terms of the heat of the greenhouse. If things get too hot, the plants will shrivel and die. Unfortunately, it is far less easy to regulate the heat of the planetary greenhouse in which we all live that it is to keep a constant temperature in your garden greenhouse.

Some gases have a greater greenhouse effect than others. Methane, for example, is far more potent greenhouse gas than carbon dioxide, but the latter is much more plentiful and does not break down as readily over time. That is why controlling the amount of atmospheric carbon dioxide is important; should there be too much of it there is a possibility that the greenhouse effect could get out of hand.

The debate here therefore rests on the question of how much is too much?

Global warming is related to human activity

This is where things are most likely to produce contention, but the claim here is merely that there is a connection between human actions and global warming. It is the extent to which this true that is up for debate.

The science seems to be clear enough. When you burn anything, be it in an industrial process or an internal combustion engine, you create a release of carbon in the form of carbon dioxide (as well as producing other residues).

This is because practically everything that is combustible contains carbon, much of it derived from natural processes that took place many millions of years ago that trapped vast quantities of atmospheric carbon in what became oil and coal. This trapping reduced the greenhouse effect and made it possible for complex lifeforms to evolve.

The release of this carbon back to the atmosphere is therefore a reversal of the aforementioned natural processes, and is largely due to the activities of humans.

Another way in which humans disrupt the carbon cycle is by destroying the natural agents that remove carbon dioxide from the atmosphere, namely plants. This is done directly by felling trees to an extent that their ability to act as a “carbon sink” is severely diminished. There are less direct effects that relate to the oceans, which are the other main carbon sink that mitigates the damage done by burning fossil fuels.

Can everyone agree?

The facts given above should be beyond contention – global warming is happening, the greenhouse effect exists, carbon dioxide is a major greenhouse gas, and human activity is affecting the amount of carbon dioxide in the atmosphere.

If anyone wishes to dispute the truth of these basic facts, they are welcome to do so. However, I would ask them to come up with very good reasons as to why the facts are incorrect. I would also ask them to stick to the facts and leave the contentious issues to one side for the time being.

There is plenty of debate to be had over such matters as whether or not these phenomena should cause us concern and what – if anything – should be done about them. By all means let’s have those debates in their proper context, but, whatever our stance might be in those debates, can we possibly agree on the basics before we get carried away with all the rest?