sue mcnab

Climate change course blog

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Climate Change course – week 6

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!


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Climate Change course – week 5

Ocean acidification has enormous implications for the functioning of natural systems. However, its human impact cannot be overlooked either. Will marine organisms be able to adapt to ocean acidification given the time scale for the predicted changes?  Increased carbon dioxide in the atmosphere is likely to lead to sea level rise. Are rising sea levels more of a threat to humanity than ocean acidification?

The timescales don’t seem long enough for those tiny intricate creatures to evolve a whole new protection mechanism. Not only will there be a tragic loss of species & habitat, but the food chain will be severely affected. Humans currently depending on fish for a living &/or food source will be forced to move, adding to the migration caused by the other danger of rising sea levels. In the UK we are currently witnessing the problems created by storms & flooding – the affect on communities, farming, power supplies, transport, & seeing the blame game that starts up between politicians, media & public. Imagine what this would be like if things really got serious – total chaos! This should be a massive wake-up call – we mustn’t do what we normally do which is to wait for the **** to really hit the fan – by then it will be much too late.

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Climate Change course – week 4

The IPCC recently published their Fifth Assessment Report (2013)report. Does the recent change in global temperatures reflect the predictions of climate models? Does the recent change in global temperatures reflect the predictions of climate models?

Whilst the press release says that models have predicted the recent change in global temps, the report itself (Chapter 9, box 9.2) mentions that the observed global mean surface temp over the last 15 yrs is below almost all model-simulated trends, whereas during the previous 15 yr period it was above. It discusses the relevance of short time period trends (10-15 yrs) to long term climate change, and the difficulties in predicting them. This issue highlights the danger of the abuse of statistics by selectively choosing which time period to study, which start time to base trends on, what factors to take into account etc. Climate modelling is clearly incredibly complex but vital, & improving all the time. In my humble opinion the case is made – we are causing damage, & for climate change deniers to mis-use or rubbish the hard work being done by climate scientists is disgraceful. We take out insurance to protect against things that we think may possibly happen with very low certainty, we visit the doctor if we think we may possibly have an illness; we are much more sure of the fact that humans are causing climate change so we should stop arguing about this & start acting-fast!

What is your view on geoengineering? Should it be used to prevent our planet warming? Post your views into the discussion.

My gut feeling is that we shouldn’t mess with nature – both in causing climate change or trying to geo-engineer our way out of it. I agree that the latter is a bit like a “get-out-of-jail free card”, to say nothing about the damage some of the schemes could cause. Far better to concentrate our efforts on preventing further damage (reducing/halting emissions, energy efficiency, reducing population growth, sustainable energy production etc). That said, I have no objection to people painting their roofs white, or any other “harmless” ideas like this – I suppose the question is “what is harmless & how do we find out?” . A classic case of How do I get to A from here? Don’t start from here! Apologies for the simplistic answer – better leave it to more learned people to decide…


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Climate Change course – week 3

Is a warming world likely to have more rain, or does it depend on where on Earth you are?

Exploring the map shows that while in the UK 2012 was the wettest on record, other parts of the world (US, Brazil, W.Australia, S.China) had severe droughts. Presumably the increase in hurricane activity in the Atlantic has a big effect on UK rainfall, & in turn is influenced by temperatures in N & S America. From what we have already learnt, a warming world will have more rain (until the oceans evaporate & we dry up!) but whether this map provides further evidence of climate change or adds complexity to the issue I don’t know – I am confused – as ever…

 What places on Earth have experienced the largest warming from 1980-2004? Are the areas that are experiencing the most warming also showing the largest variability in temperature and or precipitation?

Northern hemisphere predicted to have largest warming by 2050-74 compared to 1980-04 (if I have understood the question correctly) though if you look at 2070-95 that is spreading south to most land masses. Variability in temp (again if I have understood question right) appears similar (0.8-1.0) in most countries. But with precipitation, variability is much less in the northern regions compared to the south. Equator predicted to get increased precipitation over the period in question with less pronounced changes in north & south. More explanation on variability (ie standard deviations) needed – is it variability between each year in the period (eg 2050-74) being modelled, or between the various models being used?

What would you consider the largest threats from extreme weather events to where you live?

Other examples: increased atmospheric water vapour, decreases in the extent of mountain glaciers, snow cover, permafrost and Arctic sea ice. Largest threats here in UK are increased flooding from sea level rises, storms caused by changes to the jet stream & Atlantic conditions affected by melting Arctic sea-ice & hotter temps in US. Also increased pollution from fossil fuel emissions unless we get our act together! All the threats mentioned to public health, coastal infrastructure, agricultural productivity as well as damage to private & commercial property (eg Somerset levels right now).

The World Bank publishes a variety of environmental data, including carbon emissions (measured in kt). Create a graph to show a variety of countries at different levels of economic development by following this link to the World Bank web site. Include the USA and China in your graph. Share your graph in the discussion. You may also want to try plot carbon dioxide emissions measured in metric tons per capita. What conclusions can you draw?
In overall emissions, US long time big offender but China powering away from them. Other countries shown are relatively lower levels. But per capita, US & Australia highest although latter levelling off/falling slightly. But, other countries shown (including UK – shame!) show increasing per capita rates with exception of India. Worrying in countries where population is increasing as well – especially China where change in One child policy likely to cause pop. increase on top of rising per capita emissions. Conclusion – we need to control pop growth & per capita emissions at the same time.

Reflections on Week 3:

This week highlighted for me the problems of interpreting the mass of data that exists & drawing meaningful conclusions. I found session 3.4 “Your warming world” quite difficult & the questions maybe badly worded (sorry!). I could do with more explanations on the topic & perhaps the correct answers? I didn’t do any further research because I felt overwhelmed with statistics & didn’t think I could take any more…