Positives and negatives of global warming

What The Science Says:
The negative impacts of global warming on agriculture, health, economy and environment far outweigh any positives.

Climate Myth: It's not bad
"Two thousand years of published human histories say that warm periods were good for people. It was the harsh, unstable Dark Ages and Little Ice Age that brought bigger storms, untimely frost, widespread famine and plagues of disease." (Dennis Avery)

The best way to put this in perspective is to compare the positives of global warming to the negatives (note - this list is by no means comprehensive - please feel free to suggest additional papers in the comments below):

Positives

Negatives

Agriculture

Agriculture

  • Decreasing human water supplies, increased fire frequency, ecosystem change and expanded deserts (Solomon 2009)
  • Decline in rice yields due to warmer nighttime minimum temperatures (Peng 2004, Tao 2008)
  • Increase of Western United States wildfire activity, associated with higher temperatures and earlier spring snowmelt (Westerling 2006)
  • Encroachment of shrubs into grasslands, rendering rangeland unsuitable for domestic livestock grazing (Morgan 2007)
  • Decreased water supply in the Colorado River Basin (McCabe 2007)
  • Decreasing water supply to the Murray-Darling Basin (Cai 2008)

 

Health

  • Winter deaths will decline as temperatures warm (HPA 2007)

Health

  • Increased deaths to heatwaves - 5.74% increase to heatwaves compared to 1.59% to cold snaps (Medina-Ramon 2007)
  • Increased heat stress in humans and other mammals (Sherwood 2010)
  • Spread in mosquite-borne diseases such as Malaria and Dengue Fever (Epstein 1998)
  • Increase in occurrence of allergic symptoms due to rise in allergenic pollen (Rogers 2006)

Arctic Melt

  • An ice-free Northwest Passage, providing a shipping shortcut between the Pacific and Atlantic Oceans (Kerr 2002, Stroeve 2008)

Arctic Melt

  • Loss of 2/3 of the world's polar bear population within 50 years (Amstrup 2007)
  • Less compacted ice, hazardous floes and more mobile icebergs posing increased risk to shipping (IICWG 2009)
  • Drying of arctic ponds with subsequent damage to ecosystem (Smol 2007)
Warming causes methane to escape from Arctic regions, contributing additional greenhouse warming. The following have been observed:
  • Melting of Arctic lakes leading methane bubbling (Walter 2007)
  • Leakage of methane from the East Siberian Shelf seabed sediments (Shakhova 2008)
  • Escape of methane gas from the seabed along the West Spitsbergen continental margin (Westbrook 2009)

Environment

  • Increased vegetation activity in high northern latitudes (Zhou 2001)
  • Increase in chinstrap and gentoo penguins (Ducklow 2006)
  • Increased plankton biomass in the North Pacific Subtropical Gyre (arguably ENSO/PDO might be dominant influence) (Corno 2006)
  • Recent increase in forest growth (McMahon 2010)
  • Bigger marmots (Ozgul 2010)
  • Increased Arctic tundra plant reproduction (Klady 2010)

Environment

Ocean Acidification

Note: this is not caused by warming temperatures but by the oceans absorbing more carbon dioxide (Dore 2009).

  • Oceans uptake of carbon dioxide, moderates future global warming (Orr 2005)

Ocean Acidification

Glacier Melt

Glacier Melt

Economical

  • Increased cod fishing leading to improved Greenland economy (Nyegaard 2007)

Economical

Sea Level Rise

Sea Level Rise

Intermediate rebuttal written by Rob Painting


Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

 


Additional video from the MOOC

Interviews with  various experts

 


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