The parameters that determine our planet’s climate, including carbon dioxide, have been varying more or less cyclically for at least the last 800,000 years, each within its own ‘envelope of natural variation’. But the Earth’s atmosphere has noticed changes in recent times, and is consulting its doctor.
“And how are we feeling today?”
“Well, I’ve been up and down, truth to tell,
For the last 80,000 decades;
But now I feel really unwell.”
“Hmm. I see your historical records
Have never behaved themselves decently;
But they’ve always stayed nicely within
Certain limits – until fairly recently.
“Take carbon dioxide. It’s varied
(In case you ever have wondered)
Within really quite well-defined limits:
One-seventy up to three hundred1.
“What’s your temperature? Hmm, a bit high now –
And your oceans are slightly inflated.
I’ll call Mauna Loa2, Hawaii,
For your CO2 figures, updated.
“Hello Mauna, I’m calling
On behalf of the Earth’s atmosphere.
What’s the latest on CO2 levels?
Four hundred? You’re certain? Oh dear!
“The news is not good, I’m afraid,
But in hindsight, not really surprising.
Your envelope’s natural limits
Are breached: CO2 is still rising.”
“Oh doctor, then what is the cure?
Is there anything that I can do?”
“No, it isn’t your fault, don’t feel guilty.
It’s what everyone’s doing to you.”
1 – Parts per million (see graph, in which ‘Present’ means 2015 – the value is now above 400. For latest values, see https://gml.noaa.gov/ccgg/trends/)
2 – The mid-Pacific mountain-top observatory of the US National Oceanic & Atmospheric Administration which has been continuously monitoring and collecting data related to atmospheric change since the 1950s.