I did have a restful Christmas, albeit wrapped in the warmth of Brisbane’s humidity, but in the still of the night reality has a way of breaking through. I’ll begin with the ending of this story, as it were, by quoting what Carl Sagan said about the photograph of Earth taken from Voyager 1 as it left the Solar System:
That’s here. That’s home. That’s us. On it everyone you know, everyone you love, everyone you’ve ever heard of, every human being who ever was, lived out their lives … Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity — in all this vastness — there is no hint that help will come from elsewhere to save us from ourselves.
Here’s the pic:
That’s from a article by Andrew Glikson done back in May as CO2 levels in the atmosphere of 400 parts per million were recorded by the National Oceanic and Atmospheric Administration.
Glikson highlights the changes this implies when the full effects become apparent, according to the paleo record when CO2 levels were similar in the Pliocene:
Global Pliocene temperatures were on average about 2–4°C warmer than pre-industrial temperatures. Those temperatures drove an intense hydrological cycle with extreme evaporation and precipitation. It led to extensive rain forests, lush savannas (now occupied by deserts), small ice caps (about two-thirds of the present) and sea levels about 25 meters higher than at present.
Life abounded during the Pliocene. But such conditions mean agriculture would hardly be possible. The tropical Pliocene had intense alternating downpours and heat waves. Regular river flow and temperate Mediterranean-type climates which allow extensive farming could hardly exist under those conditions.
Glikson emphasises the rate of change, which is under-appreciated. The planet has seen nothing like it in the last 65 million years.
Sixty-five million years ago, the K-T asteroid impact resulted in a rise of more than 2000ppm CO2 and about 7.5°C over a period of about 10,000 years (or about 0.2 ppm/year and 0.00075°C per year). … The CO2 rise rate was an order of magnitude lower than current rate of 3ppm/year.
Then 55 million years ago there was the famous spike in temperature of the Paleocene–Eocene Thermal Maximum (PETM):
large-scale release of methane drove atmospheric CO2 to near-1800 ppm and temperature rise to about 5°C over a period of 10,000 years. (That’s 0.18 ppm CO2year and 0.0005°C/year.)
Again an order of magnitude lower than current rate of about 3ppm/year.
From past performance mass extinctions can be anticipated.
However, Glikson says carbon emissions may be grimly self-limiting.
It is likely that, before atmospheric CO2 reaches 500ppm, extreme weather events would disrupt industrial and transport fossil fuel-combusting systems enough to lead to reduction of emissions. However, the feedback processes like methane release, forest bushfires and warming oceans will drive CO2 levels further.
I came upon that post via a link in Graham Readfearn’s recent piece on the truly awesome effort we are putting in to rip coal out of Galilee Basin and export coal seam gas through Gladstone. Readfearn describes our effort as “both history defying and future shaping.”
It’s quite conceivable that there is intelligent life out there, intelligent enough to preserve its own habitat. In human terms Earth is the only home we are likely to have, but in human terms it is a speck in the vast void. Here on the third rock from the sun, one of hundreds of billions of suns in a galaxy 100 million light years across, where that galaxy is a pin prick in the deep, it’s hard to think we matter in the general scheme of things.
It’s all up to us, really.