Conscious Climate: Impacts

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Given the 5-25 degree day-to-day “noise” of weather fluctuations, it’s easy to miss how a slight shift in world-wide average temperatures can have massive implications for everything from ocean currents and wind patterns to sea levels, droughts and floods, the timing of seasonal biological cycles or the spread of disease. And many people are unaware that lags in the response of the earth system to current levels of greenhouse gases guarantee future additional warming roughly equal to that which has already occurred.

Of even more concern: continued temperature increases, at rates exceeding anything seen within the last several hundred thousand years, could potentially trigger natural feedback mechanisms that might amplify - perhaps many times over - the changes intiated by our 250-year-old infatuation with fossil fuels.

Courtesy of UK’s Met Office; see also full-screen version and/or Canadian summary (Oct/09).

Overview of Current and Projected Impacts
  Tapping the expertise of thousands of scientists and hundreds of reviewers from around the world, the IPCC reports offer the most comprehensive review of climate science available. But the baseline they provide is conservative in the sense that it is outdated, given the rate at which the science is progressing and the fact that it excludes aspects of the climate system (such as ice-sheet dynamics) which, at the time of printing, are too poorly understood to quantify. As the first link below suggests, the world’s climate is evolving faster than even the 2007 AR4 projected . . .

  Dangerous Climate Change 2008 Update An update of the IPCC’s iconic "burning-embers" diagram, in which major consequences of continued human interference with earth’s climate are plotted against possible future temperature increases.  
  Impacts on Natural Systems (UCAR 2007)
AR4 Impacts Summary (UCC 2007)
Impacts, Adaptation, Vulnerability (AR4, 2007)
A concise point-by-point review of the Impacts section of IPCC’s Fourth Assessment Report (AR4), from the American University Corporation for Atmospheric Research (includes an interactive map that projected global impacts by region); another excellent summary from the US Union of Concerned Scientists; and finally the actual AR4 itself.  
  Effects of Global Warming (2009)
Regional Effects of Global Warming (2009)
Two reviews of the research from Wikipedia.  
  GCC Impacts in the US (2009) From the US Global Change Research Program, the most comprehensive and authoritative report so far on the science and impacts of climate change on the United States. Access key findings, the full report, or assorted brochures and factsheets.  
  Arctic Climate Impact Assessment (Summary, 2004)
Arctic Change Indicator Website
The Arctic Climate Impact Assessment is a 13MB PDF; download it whole here or in sections here; visit the Indicator Web-site for more recent updates.  

  Aside from direct effects (such as acidification of the oceans - see below), most of the impacts of atmospheric CO2 are mediated through rising global temperatures. So an obvious first question is “How much are temperatures likely to rise . . . ?”

  Working Out Climate Sensitivity (2009) A great piece from Skeptical Science on a 2008 review article in Nature Geoscience (full PDF here summarizing recent estimates on climate sensitivity, remaining uncertainties, and possible impacts.  
  Weighing Climate Feedbacks (2008) Given the number of positive feedbacks missing in IPCC (and other ) climate models, its no wonder they are probably under-estimating current and future impacts. Can a look at ancient climates help fill in the gaps?  
  Temperature Risks Updated (MIT, 2009) Improved models point to higher global temperature risks.  
  MET Warns of Extreme Temperature Rise (2008) Vicky Pope of the UK’s MET explains how current trends in greenhouse gas emissions portend severe temperature increases this century.  

Droughts, Floods and Fresh Water
  Among the positive feedbacks triggered by a warming atmosphere is the fact that warmer air can hold more water vapor, itself a powerful greenhouse gas capable of producing further warming. Increased evaporation dries out some areas and produces heavier downpours in others, and major effects on atmospheric circulation seem to be expanding the subtropics and shifting dry zones northwards into Europe and parts of the US, and further south in Australia. And as mountain glaciers melt around the world, the summer water supplies of millions are put in jeopardy.

  Climate Change And Fresh Water (2006) From the Washington-based Climate Institute, a short summary of how climate change is likely to effect fresh water supplies around the world.  
  Drought Warning As Tropics Expand (2009)
Spreading Subtropics and Drought (2006)
These articles from New Scientist magazine explain how global circulation patterns are shifting as atmospheric temperatures rise.  
  World’s Major Rivers Drying Up (BBC 2009)
Water Woes in Andean Glaciers (2009)
Australia a Glimpse of the Future? (2009)
A BBC article on a recent American survey (here) showing flow declines in major river systems around the world, a similar piece focused on South America, and a no-holds-barred piece from Climate Progress looking at Australia.  

Extreme Weather Events
  Most climate scientists are loathe to suggest direct connections can be drawn between global warming and specific weather events, speaking more in terms of shifting probabilities: the dice are becoming more and more loaded, and not in our favor . . .

  Weather Extremes in a Changing Climate (2008) Focussed mainly on North America, a recent and comprehensive overview from the US Climate Change Science Program.  
  Hurricanes Are Getting Worse(2008) From Climate Progress, a summary of recent research on hurricanes and climate change.  

CO2 and the Oceans
  While rising water temperatures and stronger layering of the ocenas may physically weaken their critical role as a CO2 sink, the chemical effects of acidification on the biological “pump” that helps sequester CO2 in bottom sediments is uncertain (eg., see pg. 39 in this 2005 Royal Society study). The implications for many shell-forming organisms up and down the food chain, however, are likely to be negative.

  The Ocean’s Carbon Balance A beaufully-written and illustrated description of how modern research is uncovering the complex story of how Earth’s oceans help determine atmospheric CO2 levels.  
  How Long Can Oceans Slow Global Warming? This very readable 2009 article from Woods Hole Oceanographic Institution asks “How much excess carbon dioxide can the ocean hold and how will it affect marine life?  
  The Other CO2 Problem (NRDC 2009)
Coral Reefs Under Threat (2009)
Carbonated Oceans (2009)
Climate Has Major Impact on Oceans (2008)
Ocean Acidification (UK 2009)
Ocean Acidification (wikipedia)
From the Natural Resources Defense Council, a list of resources on the effect of soaring CO2 on the ocean (view their 21-minute video), plus links to five additional takes on the issue.  

Sea-Level Rise

  Nation Under Siege This interactive map shows how, beginning with just one meter of sea level rise, US cities would be physically under siege, with calamitous and destabilizing consequences. The accompanying PDF also has a chapter illustrating how easily the burning of coal for energy erases attempts - from planting trees to auto fuel economy standards - designed to limit GHG emissions.  
  CSIRO Sea-Level web-site An Australian web-site with data on ancient to future sea-levels, info on how measurements are taken, and links to further resources.  
  IPCC Estimates Too Low Filling in the blanks in the IPCC’s 2007 estimate of sea-level rise.  

Health and Disease

  Health Effects of Climate Change (Lancet 2009) This comprehensive review, published jointly by the Lancet and the University College of London, concludes “Climate change is the biggest global health threat of the 21st century” (41-page PDF here).  
  Disease Warning on Climate Change (BBC 2008) Climate change may hasten the spread of diseases that can move from wild animals to humans, warns the Wildlife Conservation Society.  
  Human Health (IPCC 2007) From the IPCC Fourth Assessment Report.  

Species Extinction

  Can Plants & Animals Adapt? (2008) From the University of Adelaide, Australia.  
  Biodiversity and Climate Change
Climate Change Impact Debated
Two 2007 pieces, one an interview with Dr. Peter Raven of the Missouri Botanical Garden; the other examining uncertainties remaining from past extinction events.  
  The Escalator Effect (Nature 2007) Rising temperatures are changing mountain ecosystems as the heat forces some species upwards.  

Security Implications
  “We will pay to reduce greenhouse gas emissions today . . . or we will pay the price later in military terms. And that will involve human lives.” - General Anthony C. Zinni, USMC (Ret.)

                    Widely recognized as a geopolitical analyst, Gwynne Dyer is a veteran of the Canadian, British and American navies, holds a Ph.D. in war studies from the University of London, and has taught at the Canadian Forces College and the Royal Military Academy Sandhurst. His book “Climate Wars” is available from Amazon; enjoy his CBC Ideas podcasts here.  
  Is This What The World’s Coming To? (2007)
Age of Consequences (2007)
National Security & Climate Change (2007)
A summary article from Nature magazine, and two of the reports on which it’s based. In the first, nationally recognized leaders in the fields of climate science, foreign policy, political science, oceanography, history, and national security provide an assessment of US foreign policy and national security implications of global climate change; in the second, eleven retired US three-star and four-star admirals and generals gather to explore climate change as a “threat multiplier.”  
  Climate Change as a Global Security Risk (2007) This German study concludes: “. . .climate change [may] draw ever-deeper lines of division and conflict in international relations, triggering numerous conflicts between and within countries over the distribution of resources, especially water and land, over the management of migration, or over compensation . . . .  
  Water Conflict in North America (UNEP 2007) Heavily-utilized water systems of the western US and Canada . . . that rely on capturing snowmelt runoff will be especially vulnerable.