* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Unit 12 - Global Warming - e
Myron Ebell wikipedia , lookup
Climate change mitigation wikipedia , lookup
Joseph J. Romm wikipedia , lookup
ExxonMobil climate change controversy wikipedia , lookup
Heaven and Earth (book) wikipedia , lookup
Climatic Research Unit email controversy wikipedia , lookup
Climate change in the Arctic wikipedia , lookup
Michael E. Mann wikipedia , lookup
Soon and Baliunas controversy wikipedia , lookup
Climate change denial wikipedia , lookup
Climate change adaptation wikipedia , lookup
Effects of global warming on human health wikipedia , lookup
Economics of global warming wikipedia , lookup
Mitigation of global warming in Australia wikipedia , lookup
Climate change in Tuvalu wikipedia , lookup
Climate change and agriculture wikipedia , lookup
Climate sensitivity wikipedia , lookup
General circulation model wikipedia , lookup
Climate change and poverty wikipedia , lookup
Fred Singer wikipedia , lookup
Climate change in the United States wikipedia , lookup
Media coverage of global warming wikipedia , lookup
Intergovernmental Panel on Climate Change wikipedia , lookup
Solar radiation management wikipedia , lookup
Climatic Research Unit documents wikipedia , lookup
Effects of global warming on humans wikipedia , lookup
Global warming controversy wikipedia , lookup
Effects of global warming wikipedia , lookup
North Report wikipedia , lookup
Surveys of scientists' views on climate change wikipedia , lookup
Climate change, industry and society wikipedia , lookup
Criticism of the IPCC Fourth Assessment Report wikipedia , lookup
Attribution of recent climate change wikipedia , lookup
Future sea level wikipedia , lookup
Scientific opinion on climate change wikipedia , lookup
Politics of global warming wikipedia , lookup
Global warming wikipedia , lookup
Instrumental temperature record wikipedia , lookup
Public opinion on global warming wikipedia , lookup
Global warming hiatus wikipedia , lookup
This slide show summarizes the scientific consensus on humancaused climate change, as embodied in the United Nationssponsored Intergovernmental Panel on Climate Change 2001 Report (www.ipcc.ch), the source of the figures shown (annotations added for this class). The skinny version is, with high confidence: We are changing atmosphere, especially by burning fossil fuels; That is changing the climate, primarily by warming; The changes so far have been tiny compared to the changes that will come if we follow business as usual; Changes will cause winners and losers, with losers far outnumbering winners if warming is large; Sea-level rise, summer grain-belt drying, and stronger storms are among the large impacts expected. Unit 12 - Global Warming Additional Points on Global Warming: In the past, environmental problems invariably generated much noise and denial and claims of huge costs to clean up, until people invented better ways, after which we solved the problems, people made money, and the cleanups became part of the economy; Plausible estimates say completely cleaning up CO2 today would be very expensive, but could be done after a few decades of serious research and development for something like 1% of the economy; That is in line with costs of other cleanups (sewers, janitors, garbage trucks, catalytic converters…), and, it is a lot of money; Slowing down emissions a bit now might buy time to avoid problems until the new technologies are in place; We will switch energy sources (fossil fuels are finite); will we switch before or after changing the world, and, who will get rich? Unit 12 - Global Warming Rise in greenhouse gases carbon dioxide, methane, and nitrous oxide over last millennium, and rise and fall in acid-rain sulfate over last 600 years, from ice-core data (sulfate and dots on gas graphs) and instrumental records (lines for gases). Changes are clearly human-caused. UN IPCC http://www.ipcc.ch Unit 12 - Global Warming Instrumental record (from thermometers) of global average temperature from 1860-2000. Corrections have been made for the heating effect of cities, so this shows real warming. From UN Intergovernmental Panel on Climate Change (IPCC), http://www.ipcc.ch Instrumental record (red) and proxy-data record (tree-rings, etc., blue with uncertainty in gray) of global average temperature over last 1000 years. Details of proxy interpretation are still debated, but, other approaches give similar results. Unit 12 - Global Warming Natural forcing explains temperature changes of a century ago but not recently; human forcing explains recent changes--Nature mattered, but now we control. UN IPCC www.ipcc.ch Effects on temperature of changing sun & volcanoes Each panel shows measured globalaverage temperature 1860-2000 (red line) and a model reconstruction with uncertainty (gray band). Effects on temperature of changing greenhouse gases & acid rain Effects on temperature of changing greenhouse gases, acid rain, sun & volcanoes Unit 12 - Global Warming Natural causes (more sun, fewer volcanoes) started warming (upper left) but switched to cooling; human causes (greenhouse gases, plus acid rain blocking sun) cooled in 1950s, now warming strongly (upper right and bottom). How much more fossil fuel is there? We’re sure of reserves; we think we have resources, and unconventional reserves and resources include oil shale, tar sands and such. Most of the fossil fuels have not been burned yet, but we’re burning much faster now than in the past. Still there to burn Burned already Unit 12 - Global Warming ??? Scenarios show different possible futures, depending on how fast economy grows and how hard humans try to clean up CO2. Change to come. Change so far. UN IPCC www.ipcc.ch Past change in CO2 is small compared to change coming, CO2 is still likely to be going up in 2100, and the world doesn’t end then (you may live past 2100…). Unit 12 - Global Warming Uncertainty arises both from not knowing what humans will do (different scenarios of human behavior are used, shown by different colors), and from not knowing exactly how nature will respond to humans (estimated by running each scenario through a range of computer models of the climate to produce the colorcoded bars on the far right showing possible changes for that scenario). YEAR ??? Change to come. Change so far. UN IPCC www.ipcc.ch Unit 12 - Global Warming Past temperature change is small compared to expected change for all scenarios and climate models tested. Change so far is small enough that only those really paying attention have noticed; future change is expected to be much bigger. All projections show temperatures rising beyond the year 2100, which is not the end of time. Projected warming in the greenhouse future, compared to changes over the last millennium. Again, all the projection curves are rising as they cross the year 2100, and the world does not end in 2100. UN IPCC www.ipcc.ch Unit 12 - Global Warming Scenario A2 is one in which the economy does pretty well, and we don’t try very hard to clean up, giving warming toward the upper end of the scenarios tested by the UN IPCC. (www.ipcc.ch) Warming of mean-annual temperature by the year 2100, in degrees Celsius. (To get Fahrenheit, multiply by 1.8; the largest warmings in the Arctic are almost 10oC or 18oF.) Unit 12 - Global Warming Experts were asked how much warming would worry them about various things. White means few were worried, and red means most were worried. Even a little warming endangers rare species (category I)--they need to move as climate changes, but humans in the way may block migration. Much warming is required before most experts are worried about ice-sheet or thermohalinecirculation collapse (category V), but beyond 2100, such warming becomes increasingly likely unless actions are taken. How the economy grows, and how we try to clean up, determine how hot it gets, as shown on the right for the year 2100--burn-it-all makes enough warming to be worried about most things by then; slowdown-some leaves a little safety zone. UN IPCC www.ipcc.ch Unit 12 - Global Warming (left) Projected sea-level rise for a range of human-behavior scenarios and from a range of models, to the year 2100. Rise over the last few years seems to have been faster than any of these projections. Projected change is from warming-caused ocean-water expansion and melting of mountain glaciers. (right) Number of people likely to be flooded by coastal storm surges (blue bars) after a 40-cm (16-inch) sea-level rise (the yellow dotted line on the left) (includes population growth to the year 2080), versus without sea-level rise (green), assuming either modern sea-walls, etc., or efforts to build more sea-walls, etc. Loss of the Greenland ice sheet would raise sea level over 7 m or 23 feet, and Antarctica almost ten times more than that. UN IPCC www.ipcc.ch Unit 12 - Global Warming