Birthday blues

Today is my birthday.  I'm 68.

I won't see the worst consequences of disastrous climate change, because I won't be here.  But my children will.  And my grandchildren will.  And anyway, what would you think of Robinson Crusoe if, when he left his island, he'd set it alight?  We are (metaphorically) setting our world alight.

So, what would be the consequences of  a 4⁰ C rise in global temperatures?

The 4°C story goes like this:

• On the present path, we may well exceed 4°C this century. At the moment Earth appears to be heading towards 1.5°C by 2030 and 2°C before 2050, and if the feedbacks kick in, 4°C some 30-50 years after that.

• Whilst it would take several centuries to a millennium or so to melt all the ice, sea levels could be up by 2–3 metres by 2100, and in the end a 4°C-warmer world would have no large ice sheets at either of the poles, or on the Himalayas; sea-levels would eventually rise by 70 metres.  This we learn from the planet’s climate history. Almost two billion people in Asia rely to some extent on rivers which are fed in part by Himalayan snow melt.

• Ocean acidification renders many calcium-shelled organisms at the base of the ocean food chain artefacts of history. There would be no coral reefs of note. Ocean ecosystems and food chains collapse. The world is full flight into the sixth mass extinction in history. If the rate of warming consistently exceeds 0.4°C per decade, all ecosystems are likely to be quickly destroyed, opportunistic species dominate, and break-down of biological material will lead to even greater emissions of carbon dioxide.

• Warmer ocean waters decrease the photosynthetic productivity of phytoplankton, and a warm ocean surface layer stays unmixed with the cooler, nutrient-rich waters below, severely reducing the algae population. Algae, which comprise most of the ocean’s plant life, are the world’s greatest carbon dioxide sink, pumping down the gas, as well as contributing to cloud cover by releasing dimethyl sulphide (DMS) into the atmosphere, a gas connected with the formation of clouds, so that warmer seas and less algae will likely reduce cloud formation and further enhance positive feedback. Severe disruption of the algae/DMS relation would signal spiralling and irreversible climate change.

• Hundreds of billions of tonnes of carbon locked up in Arctic permafrost – particularly in Siberia – enter the melt zone, releasing globally warming methane and carbon dioxide in immense quantities.  The Amazon would no longer be a rainforest, but savannah. 

• Aridification emerges over more than 30 percent of the world’s land surface. Desertification is severe in southern Africa, the southern Mediterranean, west Asia, the Middle East, inland Australia and across the south-western United States. Agriculture becomes nonviable in the dry subtropics.

• Vince Gaia in his Guardian article reports: “A wide equatorial belt of high humidity will cause intolerable heat stress across most of tropical Asia, Africa, Australia and the Americas, rendering them uninhabitable for much of the year…  To the south and north of this humid zone, bands of expansive desert will also rule out agriculture and human habitation. Some models predict that desert conditions will stretch from the Sahara right up through south and central Europe, drying rivers including the Danube and the Rhine… by 2100, most of the low and mid latitudes will be uninhabitable because of heat stress or drought; despite stronger precipitation, the hotter soils will lead to faster evaporation and most populations will struggle for fresh water.”

• Food production tumbles as a consequence of a greater than one-fifth decline in crop yields, a decline in the nutritional content of food crops, a catastrophic decline in insect populations, desertification, monsoon failure and chronic water shortages, and conditions too hot for human habitation in significant food-growing regions.

• The destabilisation of the Jet Stream very significantly affects the intensity and geographical distribution of the Asian and West African monsoons and, together with the further slowing of the Gulf Stream, impinges on life support systems in Europe, where new deserts spreading in Italy, Spain, Greece and Turkey: the Sahara has effectively leapt the Straits of Gibraltar. In Switzerland, summer temperatures hit 48°C, more reminiscent of Baghdad than Basel.. The sort of climate experienced today in Marrakech will be experienced in southern England, with summer temperatures in the home counties reaching a searing 45°C. Europe’s population may be forced into a “great trek” north.


It is a climate emergency, people.  And we must act as soon as we can to stop it getting any worse.  Alas, mankind seems bent on destroying the world we live in.  A depressing thing to think of on my birthday.