Models of climate change that model with natural and

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: rcings Model with just natural forcings observed model prediction •  black line: observed data •  yellow: data from simulations combining natural and anthropogenic forcings (red line: mean of those simulations) •  blue: data from simulations with just natural forcings Source: IPCC 2007 Is it Really Us (Humans)? Models of climate change that Model with natural AND anthropogenic forcings include only natural drivers do a poor job of predic<on. Model with just natural forcings observed model prediction Models that include natural drivers plus human ac<vi<es predict changes in global temperature very well. Current models suggest that average global temperature will undergo addi<onal increases of up to 3.5ºC (6.3ºF) over the next 50 years and up to 5.8ºC (10.4ºF) by the year 2100. While there is still political debate about climate change, there is strong scientific consensus. Source: IPCC 2007 The Scientific Consensus •  “Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise” –  National Academy of Sciences, •  “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. …Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns.” –  IPCC, spmsspm-understanding-and.html Why should we be concerned? Projected adverse impacts on humans •  Reduction in crop yields in most tropical and subtropical regions and some mid-latitude regions •  Decreased water availability in water-scarce regions (particularly in the sub-tropics) •  An increase in vector-borne (e.g., malaria) and waterborne (e.g., cholera) diseases •  Widespread increase in risk of flooding –  Due to heavy precipitation and sea level rise Many other organisms will also be strongly affected What effect might this have on these flowers and/or other organisms? Fig. 54.22 Many ArcMc Organisms May Go ExMnct in the Wild At present rates of melMng, it is likely that within the next few decades, the ArcMc Ice Cap will melt completely every summer ... with criMcal implicaMons for ArcMc organisms It’s not just Arctic species that are affected Chytrid Fungi Are Implicated in World-Wide Amphibian Extinctions Range expansion of chytrid parasite in response to warming temperatures Futhermore: models predict that 15 ­37% of terrestrial plants & animals are at risk of ex<nc<on due to climate change – this es<mate does not include other threats such as habitat destruc<on changes in temperature & precipita<on paXerns will change the distribuMon of biomes, thus impac<ng associated fauna … What Can We Do About This? Recommended Aim: global CO2 emissions will need ! to be reduced to the level of the ocean sink (i.e. to ! about 25% of their current global level) over the ! next century or so. Achieving this will be ! extraordinarily challenging….. ! The Scope of the Challenge is Compounded by Population Growth and Economic Development Emissions need to be reduced by a factor of 4. ! ! Good News: Improved energy efficiency and renewables (etc.) ! may be able to deliver a factor of 4. ! Bad News: Population growth will worsen the problem, perhaps ! by as much as another factor of 2. ! ! Increased energy use (per capita) in the developing world (to ! the EU level only) implies another factor of about 5. ! ! So altogether we probably need a factor of 40 in decarbonization ! of the global energy supply in this century. ! !
View Full Document

This test prep was uploaded on 03/20/2014 for the course BIOLOGY 171 taught by Professor Hunter during the Fall '09 term at University of Michigan.

Ask a homework question - tutors are online