Climate Change: challenges and solutions - reflections on week six

Week six, goodness me, on the home stretch now, this week we are learning about... Impacts on Human Systems.

6.1 Human health and the built environment - video

Presented by Dr. Tristan Kershaw

Another new topic for me. So keys points of interest were:

• The building industry accounts for over 50% of CO2 emissions in Britain, and is even higher in some other economically-developed countries.
• Three concepts were introduced:

1. Urban Heat Islands
• Concept first noted by Luke Howard 200 years ago - temperature difference between London and the surrounding countryside about 2 deg. C.
• In the 1960's - about 4 deg. C.
• By hot summer of 2003 difference was 9 deg. C.
• Factors that create heat islands:
• The built environment is good and absorbing and reflecting heat back on to surrounding buildings
• buildings block wind - hence less convective cooling
• better drainage - dry environment with no evaporation going on
• extra heat comes from industry, vehicles and air conditioning systems
2. Heat Waves
• a period of hot weather prolonged over several days
• the heatwave of 2003 killed 70,000 people across Europe
• the causes were mainly dehydration and hyperthermia (heat stroke)
• majority of deaths were in buildings, at night, on the upper floors
3. No name given for the third concept - but your body is an engine that produces heat
• you typically burn about 100W just watching a video
• you know how you cool down (behaviours, and sweating etc)
• if you're unable to cool down at night, any heat built up in the body during the day may mean you cook (?)
• rate of heat loss is dependent upon environmental conditions including temperature, humidity and air movement

• So in the 2003 heat wave across Europe, the vast majority of deaths were in high-rise buildings. Opening windows failed to cool people as the heat wave was calm weather with little wind, heat island effect increased the temperature even more as a result.
• If everyone was to install air-conditioning this would mean more CO2 emissions and more heat waves!

6.2 Urban Heat Islands - article

This article on the NASA website, and this article on the NASA Earth Observatory.

The first article is mainly around a study done of north-western American cities, attempting to determine what factors lead to the greatest heat island effect. Points of interest:

• Method: comparison and use of various satellite images including surface type, temperature, and visible images.
• Cities surrounded by forests show the greatest heat island effect - this is due to the contrast between city and surrounding land, cities in deserts may actually be cooler than the surround deserts.
• The distribution of building types in the city also affects the strength of the effect - denser city centres lead to more pronounced heat islands.
• Shocking fact: "The U.S. Environmental Protection Agency estimates that, between 1979 and 2003, heat exposure has caused more than the number of mortalities resulting from hurricanes, lightning, tornadoes, floods, and earthquakes combined".
• Mortality rates are affected most in the elderly and weak.
• Use of air-conditioning may lead to a rise of external temperatures - the heat presumably is pumped out into the surrounding streets.

The second article compares two images of Baltimore - land surface temperature, and land development intensity. The presence of large areas of parkland with cooler temperatures is really noticeable.

Q. How do you think the land use planning in urban heat islands could be used to reduce the scale of such islands?

A. So from these two articles it seems having smaller cities, more even distribution of development, with areas of open planting and naturally draining surfaces would all contribute to reducing the heat island effect. There are also corrective actions that can be taken, such as reducing use of air-conditioning, and painting roofs white to lead to less heat absorption. Lining streets with trees and creating green roofs would also lead to more shade and transpiration where it is needed the most. Also, positioning buildings to funnel air-flow through the city would help keep it cooler.

Interesting fact: Someone on the discussions pointed to this article - a cool car needs a 13% smaller air-conditioner, leading to a 1% improvement in fuel-efficiency overall!

6.3 Climate Change and Food Security - video

Presented by Prof. Sarah Gurr.

Key points for me:

• World population now approx. 7 billion, expected to reach 9.2 billion by 2050.
• 40% of the worlds agricultural land produces just three crops - wheat, rice and maize
• rice accounts for the main source of calories for 50% of the worlds population
• the main threat to these three crops are three particular fungi
• potato blight caused loss of 15% of Irish population during the potato famine
• distribution of harmful pathogens is shifting due to climate change - in a warming world they are moving toward the poles
• research is being carried out in three forms to protect against these effects: i) breeding varieties with stronger resistance, ii) using bioprotection using microbes found in the soil, iii) more "rational" ways to protect crops with antifungal chemistries - I guess this means better anti-fungicides(?)

6.4 The Global Food Security Programme - article

Website with lots of articles, including an FAQ, including, Does climate change affect food security?


6.5 Tackling Food Security - discussion

Q. With a growing population and improving diets there is a need to double our food supply by 2050. Identify three measures you would take meet this demand. Identify one of your measures from your list and post your solution into the discussion - be prepared to defend your choice!

A1. Be more efficient with what we already have - reduce waste either through the way food is distributed through markets and in individuals homes and shops in the developed nations.

A2. Be more effective in production - that means grow the most appropriate crops in the most appropriate ways, e.g. choice of varieties, use of fertilisers, fungicides and herbicides etc. Continue the "green revolution" to produce more food.

A3. Diversify our food sources - make ourselves less dependent upon just three food types - rice, maize and wheat, that may be at odds with the answer above!

6.6 Test

15/15 again this week, woo-hoo!

6.7 Reflect

I think on the whole I found this week slightly less engaging, I'm not sure why. I guess these two topics are more about the impacts of climate change on people, whereas up to now I've been primarily interested in the identification and prediction of climate change in itself. It took less time than some other weeks for me. Interesting topics all the same.