The Science and Economics of Climate Change Based on presentations by John Houghton of IPCC, Earthguage, the Met. Office and the Stern Review The Carbon Cycle http://eo.ucar.edu/kids/green/images/carboncycle_sm.jpg ghg_1.jpg “Greenhouse effect” ghg_3.jpg Increasing greenhouse gases trap more heat [Image 1] Earth’s surface absorbs heat from the sun and then re-radiates it back into the atmosphere and to space. [click, Image 2] Much of this heat is absorbed by greenhouse gases, which then send the heat back to the surface, to other greenhouse gas molecules, or out to space. Though only 1% of atmospheric gases are greenhouse gases, they are extremely powerful heat trappers. By burning fossil fuels faster and faster, humans are effectively piling on more blankets, heating the planet so much and so quickly that it’s hard for Mother Nature and human societies to adapt. Greenhouse gases Molecules_1.jpg Molecules_2.jpg Molecules_5.jpg Molecules_3.jpg Molecules_4.jpg Nitrous oxide Water Carbon dioxide Methane Sulfur hexafluoride Greenhouse gases Nitrous oxides Methane Sulphur hexaflouride While there are many substances that act as greenhouse gases, two of the most important are water and carbon dioxide, or CO2. Unprecedented human drivers of climate change nCarbon dioxide: a critical greenhouse gas nDramatic increase in industrial era, ‘forcing’ climate change nHigher concentration than for more than 600,000 years Global mean surface temperatures have increased V:\broadcastmet\climate\media\graphics\minmax_allnat_ann.jpg Climate models are not only used to look at how climate might change, they’re also used to figure out WHY it’s changing. When models are run with only natural influences from the sun and volcanic eruptions, they say that during the latter half of the 20^th century, we would have expected little change from normal conditions (the blue line). Only the addition of human emissions (greenhouse gases, sulfates, and ozone) produce the model results in red that most closely reproduce the black line of actual observations. So, although they aren’t perfect, climate models can reproduce many of the larger features of climate change in Earth’s distant past, and they replicate the pattern of warming in the last 100+ years. This gives us confidence that they correctly identify that the warming is due to man’s activities, and that projections of future warming are realistic. Precipitation patterns have changed •Data from World Resources Institute Computer models ipcc_fig_10_4.jpg [Image 1] The main tool for both past and present climate analyses are computer climate models. Much like the models used to forecast weather, climate models simulate the climate system with a 3-dimensional grid that extends through the land, ocean, and atmosphere. The grid may have 10 to 60 different levels in the atmosphere and surface grid spacings of about 60 by 90 miles (100 by 150 km)—the size of Connecticut. The models perform trillions of calculations that describe changes in many climate factors in the grid. [click, Image 2] The models project possible climates based on scenarios that cover a range of assumptions about global population, greenhouse gas emissions, technologies, fuel sources, etc. The model results provide a range of possible impacts based on these assumptions. Why should we care? splash_blue_puz2.png sp1_cgd_1i_new.gif Global average temperatures are expected to increase by about 2-13°F (1-7°C) by the end of the century. That may not sound like a lot, so what’s the big deal? The problem is that small changes in global average temperature can lead to really large changes in the environment. Let’s look at some of the expected changes. Consequences of sea-level rise http://environment.newscientist.com/data/images/archive/2614/26141603.jpg A rise of 5 metres would result in significant land loss Impacts on biological and social systems 20-potential change Time for thought . . . nHow much of this is about your personal behaviour and how much about how the economy is structured? nHow much is your responsibility and how much is the government’s? Or is it the responsibility of business? nWhat do you think? What does your neighbour think? What does this have to do with business? F2_2_CO2_GWP Stern Review nThe Stern Review was the first significant consideration by an economist of the environmental consequences of climate change nSir Nicholas Stern admitted he had only known about climate change for two years! n stern-review Greenhouse gas emissions in 2000 by source Business as usual is not an option Fig 13_1.jpg Headlines nWhat we do now can have only a limited effect on the climate over the next 40 or 50 years; what we do in the next 10 or 20 years can have a profound effect on the climate in the second half of this century and in the next. nBy investing 1% of GDP now (the next 10-20 years) we will avoid losing 20% of GDP later (40-50 years) nMarkets for low-carbon energy products are likely to be worth at least $500bn per year by 2050, and perhaps much more. Individual companies and countries should position themselves to take advantage of these opportunities. Main findings of the review nCO2 emissions are caused by economic growth but policy to tackle climate change is not incompatible with economic growth; nFavours the transition to a ‘low carbon economy’ which will ‘bring challenges to competitiveness but also opportunities for growth’; n‘Policy to reduce emissions should be based on three essential elements: ncarbon pricing, technology policy, and removal of barriers to behavioural change’; nArgues for the pricing of carbon through trading, taxation or regulation; nNeed for government support for low-carbon and energy-efficient technologies Socolow’s wedges: pro-technology approach wedges2.gif Each bullet point is one 1bn. Tonne wedge •Efficient vehicles: Double car fuel efficiency by 2055 •Reduced vehicle use: Halve the miles travelled by the world’s cars by 2055 •Efficient buildings: Cut emissions by 25% in all buildings http://www.ecobusinesslinks.com/images/Scooter/honda_insight.jpg Power generation •Triple the world’s current nuclear capacity •Increase solar capacity 700 times •CCS electricity: Capture and store carbon from 800 large coal power plants or 1600 large gas power plants http://commentisfree.guardian.co.uk/solarpower.jpg Change land-management systems •Halve global deforestation and double forest planting in 50 years •Apply carbon management strategies to all of the world’s farm fields http://1.bp.blogspot.com/_9RdnraXdpU8/SaomBiNaiBI/AAAAAAAACPg/_t70VGBm31Y/s400/Agnes+Nyakayira+Chig witi+Afforestation++club.JPG