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As Global Temperatures Rise

Paul Kando

This is the first year the average global temperature reached 1ºC (1.8ºF) above the pre-industrial level and world leaders in Paris agreed to keep its further rise below 2ºC (3.6ºF). But their pledges to cut emissions are insufficient to prevent a 3ºC (5.4ºF) temperature rise by century’s end. Governments now recognize that the fossil fuel era must end but, unless public pressure prevails over fossil fuel industry interests, the transition will drag out too long for major climate damage to be avoided.

Predicted temperature rises
photo credit: NASA

At 3ºC, 4.5 billion people annually will be affected by extreme heat waves, 60 million by flooding, and 1.75 billion by water shortages. Millions of square miles of cropland will be destroyed. In tropical and temperate regions production of major crops, including wheat, rice and corn, will decline. Ocean acidification will increase 62%, jeopardizing the aquatic ecosystem.

At even higher temperatures, in some areas it will be too hot and humid to work outdoors, like growing food. A substantial number of species will go extinct. At 4ºC spring snow cover in the northern hemisphere will decrease by 25% or more, with the Arctic nearly ice-free in summer as early as 2050. Food security will be globally threatened. Sea levels will rise several feet. Ocean acidification will accelerate dramatically. In dry regions drought frequency will increase. Less rainfall is likely in mid-latitude, subtropical arid and semi-arid regions, but high latitudes and the equatorial Pacific are likely to see more rainfall. Glaciers will decline in global volume by as much as 85%.

Even at 2ºC, the IPCC calculates that by 2100 1.5 billion people will be exposed to extreme heat waves and experience water shortages, while 30 million will be affected by flooding. September Arctic sea ice will decrease by 43% and northern hemisphere spring snow cover by 7%. The sea level will rise by up to 2 feet, on top of the 20th century’s 8” rise. The oceans will get 15-17% more acidic. The global volume of glaciers will decline by as much as 55%, not counting Antarctica and Greenland.

In the peer reviewed journal Nature Geoscience, Ken Caldeira of Stanford University and colleagues modeled the extent of damage from climate change to coral reefs, freshwater availability, plantlife and other vulnerable parts of the environment. The models show that the most damage occurs within the first degrees of warming. After that the damage tapers off, there being less remaining to be damaged. So, almost all the serious climate change damage could happen before 2ºC of warming. This is notably the case for both coral reefs and scarce freshwater supplies. Destruction of cropland slows down only around 3ºC of warming, after significant damage has already occurred. Needless to say economic losses will be commensurate.

Like Peace to men of good will, the Paris agreement, remains a wish. It cannot save the planet unless we, the people, act on it by becoming models for change and increasing the pressure to ensure that the pace of transition to a 100% renewable energy economy matches the urgent need.