Mark Lynas's Six Degrees: Our Future on a Hotter Planet is a powerful book. In 2001, the the Intergovernmental Panel on Climate Change (IPCC) released a landmark report projecting average global surface temperatures to rise between 1.4 degrees and 5.8 degrees Celsius (roughly 2 to 10 degrees Fahrenheit) by the end of this century. Analyzing what such temperature rises would mean for the planet, Lynas sets out to track what geologists, glaciologists, oceanographers, climate scientists, and paleoclimatologists expect, as well as what "major scientific projections" from computer modelers suggest.
Lynas divides his findings into six main chapters representing the consequences of a one- to six-degree shift in temperature rise:
Plus 1° C, the American West (from California to the Great Plains) could suffer a mega-drought lasting decades or centuries, devastating agriculture and evicting inhabitants on a scale far larger then the 1930s dustbowl. Over-exploited aquifers will fail as powerful dust and sandstorms engulf entire states. Europe, Africa, the Middle East, Asia, and Australia will face similar challenges.
Plus 2° C will bring thirst to parched cities across China. Facing a chronic shortage of water, China won't struggle to develop a more affluent lifestyle; it will fight to feed itself. Warmer seas will struggle to continue to absorb additional greenhouse gas emissions, radically altering the ecosystems that cover 70 % of the globe. On top of that, by 2040 Europe could experience temperatures endemic to North Africa today and the consequent death toll during searing summer heat waves may reach into the hundreds of thousands.
Adding 3° C will see a return to Pliocene norms when the Trans-Antarctic Mountains were covered with beech trees. Pine trees will return to regions hundreds of miles north of today's Artic tree line, and global sea levels will rise 25 meters. Other harbingers include a persistent super El Nino, desiccation of the Amazon and Australia, hyper-hurricanes, an ice-free arctic, dry Indus and Colorado rivers, and the inundation of New York City. Growing food in this habitat will prove increasingly problematic since rice, wheat, and maize yields decline by 10% for every 1° C temperature increase over 30° C. Over 40° C yields are reduced to zero. Starvation will replace obesity as an epidemic.
An additional 4° C will see the end of the Nile and Egyptian civilization. Alexandria will be flooded as Antarctic ice melts raise global sea levels by 50 meters (164.1 feet). If both major Antarctic ice sheets destabilize, sea levels could rise by a meter or so every 20 years--far outside humanity's adaptive capacity. Global warming of this magnitude would eventually denude the entire planet of ice for the first time in nearly 40 million years.
With 5° C of global warming, an inhospitable planet awaits us. Rain forests may have burned up. Rapidly rising sea levels, after inundating coastal cities, may begin to penetrate far inland into continental interiors. Human civilization will be confined to small areas limited by of drought and flood. At the highest latitudes, Siberian, Canadian, and Alaskan rivers will experience dramatically increased flows due to torrential rain. East Asian monsoons will dump nearly a third more water in the Yangtze and nearly 20% more in the Yellow River. The United Kingdom will experience severe winter flooding as reset Atlantic weather patterns lash Britain, Scotland and Ireland.
At 6° C, Lynas describes our situation as descending into the Sixth Circle of Hell, an earthly inferno. Terrifyingly, our planet could reprise conditions last experienced during the Paleocene-Eocene Thermal Maximum. Disruption on this scale could unleash massive amounts of methane hydrates, resulting in runaway global warming and the planet might began to emulate Venus. This would be a pace of warming far too rapid for meaningful adaptation by natural ecosystems. Mass extinction will rule the day as the earth recreates itself.
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Are we ready to make some changes? We are already in the pipeline for a devastating future. To climb out, we need to realign radically both our personal lives and our global and national politics. Although Lynas certainly does not prescribe any insta-fixes, he proposes that living simply, in community and intensely locally, is our best course. As he writes at the end, "An outdated view still prevails that a low-carbon lifestyle requires immense personal suffering and sacrifice. In my view, nothing could be further from the truth. All the evidence shows that people who do not drive, do not fly on planes, do shop locally, do grow their own food, and do get to know other members of their community have a much higher quality of life than their compatriots who remain addicted to high-fossil-fuel-consuming lifestyles." He continues, "It seems to me that this low-carbon society would be one that remembers that our planet is a unique gift." While he makes it clear that he is not talking about any utopia, the choice is clear: "Unless we do constrain carbon, life will very largely not go on at all."