Do I have Ebola Virus or a Hangover?

I feel hot. my head aches, I'm sweating, my muscles and joints ache, my throat is sore, and I can't seem to move. Am I sick?

The planet is warmer than it used to be, has heavily polluted oceans and atmosphere, is experiencing sea-level rise and Arctic sea-ice decline, is losing forests and biodiversity, seems to be experiencing more extremes of weather (in impact, if nothing else). Is it sick?

There are good reasons why doctors accumulate evidence before proceeding to diagnosis, even while sometimes treating symptoms. Two things are important: context and range of symptoms.

Why context? Take the first example. If I've been working as a nurse in a hospital in Liberia and I exhibit the symptoms described, one potential diagnosis which requires evaluation is the Ebola virus. Which would be bad.

On the other hand, if I played rugby yesterday in heavy rain, in the scrum, drank ten pints of beer afterwards during a lively singalong in the clubhouse, then walked home, and haven't been anywhere near West Africa or anyone who has been there recently, I might well describe the same symptoms to my doctor, but the diagnosis is most likely to be that a) I'm hung over, b) I'm too old to play serious rugby in the scrum and should know better - how do I expect my body to react? and c) Even if you are too drunk to feel it, walking home in just a shirt in forty degrees may have stimulated a reaction.

It is not just important to look for the context, it is essential. To answer the question 'why' requires proper investigation.

Why range? If I describe just one of those symptoms, say a sore throat, with none of the others, there could be several explanations or diagnoses, but hundreds can be eliminated because the symptom is not tied to any others. A sore throat and a headache might suggest a head cold. Add a temperature and aching muscles, perhaps influenza. Even with a large range of symptoms, placed into a context, a likely explanation is reasonably easy to find.

So, to Climate and the internet. There are very good reasons why it is important to gather evidence for a range of global conditions before attempting a diagnosis. Isolating one element is not very helpful, and cannot provide enough information on which to make any secure conclusions. One way to check out the 'records' is to use the IPCC assessment summaries, since they provide a reduction to readable size of a huge amount of very diverse information.

But you will very often see people arguing about, for example, whether the global temperature record is reliable, or if it is showing that the world is warming, or if the physics of AGW is a reasonable explanation. The reason that many of these people try to focus a reader's attention on any one of the possible 'problems' with the world and attempt to cast doubt on it's validity is because anyone who looks at the big picture cannot possibly be fooled.

As soon as anyone with a reasonable degree of intelligence looks at the range of evidence- the symptoms of the health of the world's natural and human systems - it becomes clear that there are a lot of bad signs in all sorts of places, that there are long-term persistent trends in many diverse measurements (the distribution of beetles, the volume of Arctic sea ice, global ocean temperatures, etc etc) -in other words, that the World is sick.

So it is extremely rare to see any genuine 'climate sceptic' looking at all the evidence. Or any of the evidence. Most often, what you will see is a recycled meme picked up second hand and spouted without thought as demonstration (as often as not) of a person's political or metaphysical world-view (okay, I'm being generous here).

So here is a suggestion. When you read a comment stream or argument on the web, ask yourself - is there more than one 'symptom' at question, or a 'single issue' focus? If someone is insisting on dealing with a specific 'fact' (often, these are actually false anyway), ask yourself (or them) whether they are seeing the big picture.

It's not about whether this year is warmer than last year in Alaska, or whether there is more or less ice than the long-term average this year in the Arctic, or whether any one scientist or another is correct. It is, and you know it is, much, much bigger than this.