Climate change impacts, ranking severity


in Economics, Science, Security, The environment

These are summer days and the blogging is slow. In the spirit of audience participation, here is a quick poll.

Which three of the following climate change impacts do you expect to be the most severe? Please answer first for 2050 and again for 2100. You can interpret ‘severity’ however you like: economic cost, number of deaths, total damage to ecosystems, etc.

  1. Sea level rise
  2. Droughts and floods
  3. Extreme weather events
  4. Ocean acidification
  5. Ecosystem changes (such as invasive species)
  6. Effects on pathogens (such as malaria)
  7. Agricultural impacts
  8. Impacts on fresh water quantity and quality
  9. Other (please specify)

Clearly, there is some overlap between the options. There are also second-order effects to be considered, like the impact of agricultural changes on inter- and intra-state conflict.

{ 17 comments… read them below or add one }

Anon August 14, 2008 at 10:33 am

Other (economic costs incurred due to listening to radical activist environmentalists)

R.K. August 14, 2008 at 11:45 am

I would guess extreme weather for 2050 and sea level rise for 2100.

Ocean acidification is a big wildcard. It might be no big deal and it might be huge.

Sarah August 14, 2008 at 4:07 pm

2050: 8, 7, 6, plus ‘other’ referring to second order changes in human activity which contribute to deforestation (eg. palm oil instead of rainforest).
2100: basically the same again, with a query on 1.
A geographer I talked to a while back said that ‘back of the envelope’ calculations by leading glaciologists suggested Greenland would take a very, very long time to melt (certainly over 100 years) so huge sea level rises would be a long way in the future if they happened at all.

I’m not very worried about 3, since extreme weather events like tornadoes are caused by baptists

Milan August 14, 2008 at 4:14 pm

A geographer I talked to a while back said that ‘back of the envelope’ calculations by leading glaciologists suggested Greenland would take a very, very long time to melt (certainly over 100 years) so huge sea level rises would be a long way in the future if they happened at all.

People said the same thing about the Arctic icecap.

Supercomputer models are not up to the task of determining how the climatic system will change in response to radiative forcing changes. That is especially true in relation to feedback effects (like how loss of reflective ice begets further heating). I take no comfort from ‘back of the envelope’ calculations.

Litty August 14, 2008 at 4:25 pm

If even the experts don’t really know, how can members of the general blog-reading public be expected to make a meaningful contribution?

Sarah August 14, 2008 at 4:25 pm

Sure, the ‘conventional wisdom’ of academia can be wrong & is always changing with new evidence. Reputedly, the glaciologists’ point was that even if we assumed that glaciers in Greenland would start to move as fast as any glaciers are known to have done (much, much faster than Greenland glaciers in the past) then the place is so vast that it would take a very long time for all that ice to reach the coast. That seems rather different to the Arctic where the ice was always floating on the sea.

Milan August 14, 2008 at 4:30 pm

It wouldn’t take the complete melting of Greenland to produce devastating consequences. Losing the whole ice sheet would incease sea levels by seven metres. A rise of just a metre or two would have a huge effect on many cities and agricultural areas.

Also, ice melting is not the only source of sea level rise. As the ocean warms, it also expands. The contribution of just thermal expansion might approach one metre by 2100.

Milan August 14, 2008 at 4:32 pm

If even the experts don’t really know, how can members of the general blog-reading public be expected to make a meaningful contribution?

Perceptions matter. Knowing which probable manifestations of climate change worry people has value for everyone from environmental organizations designing campaigns to industry groups designing counter-campaigns.

Milan August 14, 2008 at 4:39 pm

The Fourth Assessment Review (4AR) of the IPCC says this of sea level rise:

“Sea level rise
(m at 2090-2099 relative to 1980-1999)
Model-based range
excluding future rapid dynamical changes in ice flow

B1 scenario – 0.18 – 0.38
A1T scenario – 0.20 – 0.45
B2 scenario – 0.20 – 0.43
A1B scenario – 0.21 – 0.48
A2 scenario – 0.23 – 0.51
A1FI scenario – 0.26 – 0.59

Because understanding of some important effects driving sea level rise is too limited, this report does not assess the likelihood, nor provide a best estimate or an upper bound for sea level rise.”

Milan August 14, 2008 at 4:40 pm

See also:

Unbalanced sea level rise
July 9th, 2008

Sarah August 14, 2008 at 4:53 pm

I gotta say that my laywoman’s understanding of the IPCC models on sea level rise is that it conforms to my earlier claim “huge sea level rises would be a long way in the future if they happened at all”. That’s not to say that we shouldn’t worry about it, just that it doesn’t make my top 3.
So saying, I wouldn’t rush to buy a house on low lying coastline or floodplain.

Milan August 14, 2008 at 5:01 pm

It is certainly possible that the relatively limited sea level rise envisioned by the IPCC will prove accurate.

That said, there is certainly some degree of preliminary evidence showing that things can happen much faster.

Of course, that is also true for several other possibilities on the list above.

(More on Greenland and climate)

DeLaina August 14, 2008 at 5:23 pm

6: Effects on pathogens
7: Ag impacts
8: Impacts of freshwater

At 2100 the pathogen worry will have disapated (they change pretty fast, my guess is that by 2100 it will have kind of “evened out” so to speak) to be replace by ecosystem changes

Tom August 15, 2008 at 12:19 pm

I think the big question isn’t what climate change will do on its own, but what it will do along with other changes. For instance, some of these:

* The rise of China
* Falling world oil and gas production
* The further weakening of the United States
* More Russian aggression
* Global pandemics

And so forth

. August 21, 2008 at 11:51 am

According to the IPCC report—whose wording was agreed to by every member government, including the Saudis, the Chinese and the Bush administration—the earth is on an emissions path headed towards more than 5°C warming from pre-industrial levels this century.2 With such warming, the world faces multiple miseries, including:

* Sea level rise of 80 feet to 250 feet at a rate of six inches per decade (or more).
* Desertification of one third the planet and drought over half the planet, plus the loss of all inland glaciers.
* More than 70% of all species going extinct, plus extreme ocean acidification.

. August 23, 2016 at 2:08 pm

“UNTIL the 1970s Basra’s climate was like southern Europe’s,” recalls Shukri al-Hassan, an ecology professor in the Iraqi port city. Basra, he remembers, had so many canals that Iraqis dubbed it the Venice of the Middle East. Its Shatt al-Arab river watered copious marshlands, and in the 1970s irrigated some 10m palm trees, whose dates were considered the world’s finest. But war, salty water seeping in from the sea because of dams, and oil exploration which has pushed farmers off their land, have taken their toll. Most of the wetlands and orchards are now desert. Iraq now averages a sand or dust-storm once every three days. Last month Basra’s temperature reached 53.9ºC (129°F), a record beaten, fractionally, only by Kuwait and California’s Death Valley—and the latter figure is disputed.

Unlike other parts of the world where climate change has led to milder winters, in the Middle East it has intensified summer extremes, studies show. Daytime highs, notes an academic study published in the Netherlands in April, could rise by 7ºC by the end of the century. Another study (by the UN) predicted that the number of sandstorms in Iraq would increase from 120 to 300 a year. The UN’s Environmental Programme also estimates that the harsh climate claims 230,000 lives annually in west Asia (the Arabian Peninsula and the Fertile Crescent), making it a bigger killer than war. Things are so bad that even Jabhat al-Nusra, a terrorist group, is preaching the virtues of solar panels.

. February 22, 2018 at 6:26 pm

According to figures released on January 4th by Munich Re, a reinsurer, global, inflation-adjusted insured catastrophe losses reached an all-time high of $135bn in 2017 (see chart). Total losses (including uninsured ones) reached $330bn, second only to losses of $354bn in 2011.

A large portion of the losses in 2011 was caused by one catastrophe: the earthquake and tsunami in Japan. Losses in 2017 were largely traceable to extreme weather. Fully 97% were weather-related, well above the average since 1980 of 85%. If climate change brings more frequent extreme weather, as Munich Re and others expect, last year’s loss levels may become depressingly familiar. Already, the data show many more frequent high-loss events since 2000—lots of them weather-related—than in the two preceding decades.

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