“Humanity has long since run down the clock on climate change, It is one minute to midnight to prevent catastrophe.”—Boris Johnson at COP26, November 2021
Intensifying media blanket coverage means most of us were fed up with “last-chance-saloon” mood music before COP26 even graced “The Dear Green Place”. It is now going well, a suspiciously politically motivated strike by GMB waste workers notwithstanding. While much has been made of Chinese and Russian leaders being no-shows and India making promises for 2070, not 2050, the fact that virtually everyone is there (192 countries sent delegates) means it may be the best we can do.
Talk in the run-up focussed on the goals of slowing, rather than halting, global warming, with a 2 deg C rise as a ceiling and a 1.5 rise an aspiration. A UN study predicting 2.7 rise under current commitments may be discouraging news, but, equally, it could act as a spur.
A short blog like this is no place to rehearse all the arguments. But a discussion of the concrete consequences might focus minds better than temperature generalities. It is clear that the world is already suffering weather instabilities from climate change but more permanent damage is in the offing and from which full recovery is unlikely. This the juggernaut of sea level rise.
“The global mean water level in the ocean rose by 0.14 inches (3.6 millimetres) per year from 2006–2015, which was 2.5 times the average rate of 0.06 inches (1.4 millimetres) per year throughout most of the twentieth century.”—NASA Sea Level Research Laboratory, Hawaii
By the end of the century, they predict a global mean sea level rise of one foot (0.3 meters) above 2000 levels, provided greenhouse gas emissions fall to a low level in coming decades. This would be required to follow the 1.5 degree model, together with a linear extrapolation of the present rate of rise. This appears optimistic, because:
- The 2.7 degree rise is the most probable future temperature
- The likely disappearance of Arctic sea ice in summer will make the albedo of the Northern Hemisphere darker, causing more heat to be retained
- Such warming will start to melt the Greenland and Antarctic ice sheets, which have trapped 70% of the world’s fresh water
Neither the melting of glaciers, nor of sea ice causes appreciable rise in sea level; the former is relatively small and the latter already displaces the same amount of water as it floats. But the ice sheets are entirely another matter. Lying on land to a thickness up to 3 km, their melting would raise sea levels by a catastrophic 58 metres.
Long before that, the melting that is taking place and the thermal expansion of the seas through warming can cause trouble enough. Taking the more brutal 2.7 degree scenario and another factor of 2.5 for increase in sea level rise gives an increase of 1m over this century. In itself this could turn areas of low-lying farmland near the sea into salt marsh. But increasingly violent weather adds storm surges, caused by high winds and a drop in air pressure in the eye of such storms. This can add over 1m to the height of a tide. In 2005, Hurricane Katrina created a storm surge over 4m, which inundated much of New Orleans. In 2012, Hurricane Sandy flooded coastal New Jersey and parts of New York City.
The UK defines HMWS (High Mean Water Springs) as the highest a tide reaches. But, in reality, this could be overtopped by another 2 metres if all factors coincide. Such a “great flood” overwhelmed the Essex coast in 1953 and 53 people died. Prepared sea defences, such as most of the Netherlands or the Thames Barrier protecting London, would probably withstand such an event. Most of the world enjoys no such protection.
In future, such events as the 1953 flood would rank minor among the world’s problems. Much of Bangladesh is already underwater for a time and inhabitants displaced. The American Gulf coast is vulnerable along much of its 1,600 mile length. Deltas, like Vietnam’s Mekong are vulnerable. Most Pacific atolls would soon become uninhabitable. Almost all coastal cities would suffer damage along their shores.
Were a combination of sea level rise, storm surge at high Spring tide add 3m to ‘normal’, entire cities would be lost. Though the waters might recede, damage and the likelihood of repetition would make re-occupying them to risky. Cities at risk of abandonment as a result of such occurrences include:
- High Risk: Alexandria, Egypt; Algiers, Algeria; Brisbane, Australia; Darwin, Australia; New Orleans, LA USA; Quingdao, China; Beirut, Lebanon; Georgetown, Guyana; Venice, Italy, Wellington, New Zealand
- Medium Risk: Adelaide, Australia; Bridgeport, CT USA; Colombo, Sri Lanka; Dohar, Qatar; Le Havre, Mobile, AL USA; France; Miami, FL USA; Perth, Australia; Rijeka, Croatia
- Low Risk: Alicante, Spain; Atlantic City, NJ USA; Bangkok, Thailand; Belfast, Ireland; Benghazi, Libya; Hull, England; Galveston, TX USA; Hiroshima, Japan; Izmir, Turkey; Norfolk, VA USA; Panama City, Panama; St Petersburg, Russia; Trieste, Italy; Vancouver, Canada
These lists are neither exhaustive, nor definitive. But they do a sense of both the diversity and the importance of cities under immediate threat. Many others would suffer partial inundation and recover, as New Orleans did. Every metre rise in sea level would shift cities up one stage. Such lists could be extended to include hundreds of smaller cities, thousands of towns and, probably, millions of villages.
The key point is that, taken together with widespread loss of agricultural land and the millions of displaced people, few, if any, countries would have the resources to look after others so afflicted. Even advanced countries would be pre-occupied with looking after their own damage and displaced citizens and to even maintain their economy.
This does not imply the collapse of civilisation, but it would mean severe drops in living standards and quality of life. Landlocked countries like Switzerland would be unable to compensate this scale of loss.
Bad though this may seem, even more catastrophic scenarios exist. Any serious melting of the Greenland and Antarctic ice sheets multiply the problem well before any 58 metre Armageddon. Well before that level, civilisation as we know it would disappear, along with entire countries. Londdon;s and Netherland’s sea defences may still be holding out but they would fall into one of the following lists of key cities likely to be abandoned with each metre rise in sea levels.
- 4-Metre Rise: Bruges, Belgium; Cherbourg, France; Fort Lauderdale FL USA; Iskenderun, Turkey; Ravenna, Italy; Recife, Brasil; Shanghai, China; Southampton, England; Stockton, CA USA; Tunis, Tunisia
- 5-Metre Rise: Basra, Iraq; Cagliari, Sardinia; Camden, NJ USA; Dunkirk, France; Kaliningrad, Russia; Tel Aviv, Israel, Sapporo, Japan
- 6-Metre Rise: Bordeaux, France; Bremen, Germany; Charleston SC, USA; Channai, India; Luanda, Angola; Massawa, Eritrea; Riga, Latvia
- 7-Metre Rise: Biloxi MS USA; Hamburg, Germany; Honolulu, HI USA; Tokyo, Japan; Ho Chi Minh City, Vietnam; Ostend, Belgium; San Sebastian, Spain
- 8-Metre Rise: Exeter, England;Hue, Vietnam; Manila, Philippines; Monrovia, Liberia; Nice, France; Portsmouth, England; Vladivostok, Russia
- 9-Metre Rise: Antwerp, Belgium; Corpus Christi, TX USA; Karachi, Pakistan; Reykjavik, Iceland; Salvador, Brasil, Tricomalee, Sri Lanka
- 10-Metre Rise: Baltimore, MD USA; Bandar Abbas, Iran; Barcelona, Spain; Belem, Brasil; Calcutta, India; Cayenne, French Guyana; Hanoi, Vietnam, Kingston, Jamaica; Long Beach CA USA; Mogadishu, Somalia, Perth, Scotland; Philadelphia PA USA; Sacramento, CA USA; Taipei, Taiwan; Valparaiso, Chile
If global warming totally melted the ice sheets, even if the resulting weather permitted crops to grow and civilisation to hang on, the world would be literally unrecognisable. Half the capital cities of the world would be gone, including Washington and Beijing. Almost ALL European capitals would be gone—only Madrid, Zurich, Vienna, Prague, Sofia and Athens would remain. Budapest would be a coastal city. So would St Louis MO, Strasbourg, Chesterfield and Vitebsk, Russia. Wales would be an island and the Black Sea would flow across the Kalmyk steppe to fill the Caspian basin.
And the good news? Well, the Suez Canal would be superfluous and Antarctica would finally be available for colonisation.
Watch “Earth Under Water“, a one-hour documentary on the Smithsonian Channel (Channel 56 on Freeview, UK)
An earlier post on the same topic, discussing impact on my local patch of East Lothian, was published here in August 2021. See: Can You Canute?