Lecture4
- 1. Lecture 4. Impacts of climate change: flooding, agriculture, disease, economy Maslin Chapter 5 and 6
- 2. Main Impacts 1. Coastlines 2. Storms and floods 3. Heat waves and Droughts (Lecture 9) 4. Health 5. Biodiversity (Lecture 5) 6. Agriculture
- 3. Background General consensus that CC will have wide effects on natural environment, human society and economies IPCC Fifth Assessment Report (AR5) 2014 http://www.ipcc.ch/report/ar5/ has summarised expected global impacts: many countries produced their own national impact Impacts depend on Where you live Amount of change - a range of warming predictions Consensus (G8 meeting at Gleneagles 2005, as well as IPCC) that within 2ºC increase by 2100 manageable (some will gain and some lose) but beyond 2ºC all will lose
- 4. Climate change risks as function of increasing global temperatures Hunger, Malaria, Flooding Water shortage
- 5. Main problems Unlikely we can keep temperature increase below 2ºC because already (by 2009) rise of 0.76ºC Even if atmospheric CO2 kept to 2000 levels, would still add, at least, another 0.6ºC Inability to predict the future, and how society will respond
- 6. Example of future CO2 scenario • In UK, car usage up to 2030 could eliminate cuts in O2 emissions since 2000 • Transport accounts for ¼ global emissions • Fastest growing sector (70% of this road transport • Cars/person in USA = 1.5/1, China 1 in 30, India 1/60 Traffic in Hyderabad
- 7. Coping strategies Humans can survive in extreme environments from Arctic to Sahara but problems when predictable extremes of local climate exceeded eg. European heat wave in 2003 killed 15,000 ppl in France alone (many consecutive days of maximum temp >30ºC) and 35,000 over Europe Extremes in one region may be considered normal in another Each society has a ‘coping range’of weather with which it can deal (Figure 17 Maslin) Eg. in UK homes no aircon, but as summer temperatures increase and heat waves become common, coping range of homes will be exceeded and will need aircon
- 9. Society’s coping range and extreme events • In present climate, coping range encompasses all variation in weather including almost all events • As climate moves to a new average, if coping range stays same, extreme events not covered • Coping range can be extended by more flexibility and resilience in peoples’ behaviour according to IPCC predictions (eg. temp. inc by >2ºC and global mean sea level inc. by 18-59cm, by 2100) • This may work if climate change is a gradual linear (not sudden) response (lecture 1)
- 10. Climate change, society’s coping range and extreme events
- 11. Comparison of 2003 European heat wave with past and future summer temperatures
- 12. 1. Coastline • Half world’s population inhabits coastal zones, which have most fertile and productive land, so dense populations • IPCC predicts sea level rise 18-59cm by 2100, some due to thermal expansion of oceans, rest to icecap melt (Houghton p.146) • Some uncertainty due to Antarctic ice shelves • Developed countries response- add sea walls • Worst hit (i)Island nations eg. Maldives, (ii) and developing countries with large deltas worst hit – Bangladesh, Egypt, Nigeria, Thailand and (iii) low lying countries already protected by sea walls eg. Netherlands
- 13. Coastlines: Bangladesh Bangladesh 120m popn., Ganges delta, agriculture the main economic activity for 85% of popn. living at edge of subsistence 0.5m sea level rise may not seem much but already annual flooding occurs 10% land lost with 0.5m rise Sea level rise compounded by subsidence due to groundwater extraction, so sea level rise more like 1.8 m by 2100 Impossible to protect with sea walls
- 14. Sundarbans economy: Over 85% ppn in fishing, agriculture (paddy rice, cotton, oil seed, pulses, potatoes) and wood products Most farming families practice subsistence agriculture and most farmers landless Recent reports suggest much agricultural land lost due to inundation
- 15. Coastlines: Bangladesh • In addition, Bangladesh prone to storm surges during cyclones, at least 1 per year • Storm surge of Nov. 1970 killed 3-500,000 people • Sea level rise also threatens saltwater intrusion into fresh groundwater – already saltwater extends seasonally inland up to 150km and farmland increasingly saline
- 16. Responses • Fishing industry may relocate • But for agricultural populations, no more available land • Must study all aspects of the problem including sediment brought by rivers and use this combined with dykes and sea defences
- 17. 2. Storms and floods • 1951-99 Storms and floods cause huge economic loss eg. Hurricane Katrina caused $US150billion of damage (GDP of HK =$243b) • Model predictions- proportion of rainfall as heavy rain will increase, as will year-to- year variability- This will increase flooding events, and make agriculture more risky • Monsoons will strengthen due to predicted increase in land temperatures relative to sea (2/3 world popn lives in monsoon belt)
- 18. STORMS AND FLOODS CAUSE 76%OF GLOBAL INSURED LOSS
- 19. Hurricanes/typhoons Warmer oceans spawn more typhoons Evidence number and intensity in N. Atlantic and W. Pacific increased last 3 decades More damaging to developing countries Katrina (2005)caused 1500 deaths Mitch (1998) in Central America caused 20000 deaths – less intense than Katrina, but set back the economy of Central America for a decade Developed countries contingency measures eg. Thames barrage closes when high tides expected
- 20. 3. Heat waves and droughts • As rainfall becomes more concentrated and intense, droughts will increase • Heat waves and droughts are major killers • Heat waves select the old and weak – night-time temperatures most damaging but avoidable by better home design or install air con • Slide 9 – summer 2003 heat wave will be average temperature in 2050 Droughts (Lecture 9)
- 21. 4. Health Heat-related deaths – depends on local populations’ adaptation Access to drinking water Spread and Transmission of infectious diseases Affordability of food
- 22. Food affordability Bio-fuel production Bio-fuel (ethanol) from sugar cane, maize less polluting than fossil fuels BUT - ethanol needed to fill one car tank could feed a person for a year! takes agricultural land Expansion of meat-eating For 1kg meat, 8kg grain required Both of the above cause price of basic food (grain) to rise
- 23. South China Morning Post: 21.05.14 China’s meat imports to increase over 3,500% to 250b by 2050
- 24. 5. Agriculture • Can warmer world feed itself? • Focus on cereals • Expected temp. increase would cause fall in production globally • However buffering effects – inc. CO2 causes plants to grow faster • Farmers generally adaptable- vary planting time, switch to different varieties • Also food prodn has doubled since 1960s and is expected to continue this trend
- 25. Wheat in North America
- 26. Agriculture • Most pessimistic study (UK. Met Office) suggests by 2060 agric. production will inc. by 90%, compared with 94% if climate did not change • However much cereal-producing land now needed for biofuels or for fodder for livestock • Also, poorest countries least adaptable, and are victims of globalisation
- 27. EU Beef and Butter mountains • Developed countries heavily subsidised to protect farm jobs • Dumped in developing countries at prices below production cost • Developing countries’ own production cannot make profit – industry collapses • Eg. cotton in Benin, corn in Mexico, wheat in Kenya
- 28. Globalisation impacts • Developing countries export cash crops eg. tea coffee, cocoa rubber, cotton, but cannot feed themselves • Benin’s cotton yield 4X that of USA, but US subsidises farmers US$3.9B- twice the GDP of Benin • Benin cannot get a fair price for cotton
- 29. What do we really pay for when we purchase a pound of coffee?
- 30. Example of coffee in Uganda • Warming of 2o C will reduce suitable areas by 90%, but implications unknown ---- • If other coffee growing areas similarly affected, price of coffee will increase • Therefore the remaining 10% area will make more money • Unpredictability requires broadening of agriculture base esp. developing countries that rely on single or few crops • This difficult • Also clear that EU and US agric. Subsidies and World Trade agreements have greater effect on global food prodn than global warming will have • No solutions- collapse of WTO talks in 2008
- 32. Summary • Predicted levels of global warming over next 100yrs will affect all forms of life on earth • In many cases will be non-linear in that spp. may adapt to small warming but above certain level damage may escalate rapidly • Impacts on Table 11.1 seem pessimistic but some result from multiple threats besides warming