sue mcnab

Climate change course blog

Climate Change course – week 6

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Impacts on Human Systems

Human Health & the Built Environment

Urban Heat Islands: temperature in cities higher than rural areas. This is due to proximity of tall buildings, reduced air circulation, drainage reducing evaporation, paved surfaces, removal of vegetation limiting plant transpiration (plants use solar energy during photosynthesis & respire water which cools the air), dark infrastructure such as black roofs etc which absorb heat, & heat generated by vehicles, factories & homes.  The larger the city and the more densely packed the buildings, the larger the heat island effect.  Cities in forest regions have a higher heat island than those surrounded by farmland or desert.

Goddard Space Flight Centre researchers use data collected by satellites to show how land surface temperature correlates to land development in cities around the US.

Heat islands cause power usage to surge (air conditioning etc) but also increase mortality of the elderly & those with respiratory & cardio-vascular illnesses.  Risk is at night when the body needs to cool down after heating during the day.  The cooling effect of evaporation at night is absent in cities & this can be exacerbated by air conditioning due to the heat expelled into the streets through their use.

How can cities be better designed to mitigate this?  More trees & parks interspersed throughout compact urban cores, painting road & building surfaces white instead of black, planting green roofs – complex problem & each city will have its own solution.

Climate change & food security

Rapidly growing world population.  86% will be living in less economically developed countries.  40% of land used to grow 3 main food staples – wheat, maize & rice. Rice most important of these – main food source for 50% world’s population.  Potatoes also increasingly important.  Need a secure food supply – needs to double in size by 2050.  Food supply security under threat, climate change being one of the factors.  Not just water shortages but also crop disease.  New ones emerging, & because of warming world, crops & their distribution moving to higher latitudes, polewards.  Since 1960’s “green revolution” due to fertilisers, herbicides, pesticides & fungicides, & also to greater farm mechanisation & intensification.  Large monocultures put food supply security at greater risk from pests & pathogens.  Spread of pathogens through crops has devastating effect on human populations.  Most serious is fungi – maize, wheat & rice threatened by 3 particular fungi & the loss of crops caused by these costs US$60billion pa.  A concerted attack by these fungi could result in us only being able to feed 38% of the world’s current population.  Pathogens on the move to new geographical areas threatening new crop species.  Fungi moving polewards 7km pa.

Tackling food security

Like a majority of the comments below, educate people to eat less, eat better (& especially less meat) & stop wasting food. Educate governments to take on the food industry. I also liked the earlier post (sorry-can’t remember whose) linking to – an interesting way to produce food. Final thought – if we all went on the 5:2 diet, think how much healthier we’d all be, how much better off we’d be financially (buying less food & not wasting it on diets & health fads that don’t work) & how much food we’d save… Lots of other good suggestions below so I won’t repeat them.

Reflections on week 6:

Another interesting week.  important themes: heat islands & the need to rethink our cities – remember that ridiculous building in London last summer! (; pathogens affecting food crops (I’d always thought that water supply was the main concern).  Most interesting: looking through people’s comments – good to know there are so many like-minds out there because you can start to feel you’re in a minority of one sometimes!


Author: suemcnab

I've been in IT (developing & supporting my own software) for a long time & now want to get involved in new activities! I am very interested in & concerned about the issue of climate change & want to learn more about it.

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