Hurricanes and storms on both sides of the Atlantic appeared to encore the Inter-Governmental Panel on Climate Change. It had just concluded the finalization of a special report on the impact of a 1.5 degree Celsius global warming above preindustrial levels. Meeting in Incheon, South Korea (October 1-5), its three working groups of experts and government officials have huddled and jousted to strike a consensus on what will be necessary to restrict warming to 1.5 degrees Celsius when the globe is already up one degree. What will earth be like with this level of warmth and what will happen if we fail?
Two earlier versions (January and June 2018) of the report were depressing to frightening. They were made available for about a month for comment by experts and interested parties. The real problem is a narrow window because human activity in the world emits 40 billion tons of CO2 per year -- about 90 times the emission from volcanoes. At some point, there will be enough in the atmosphere where the 1.5 degree rise will be a foregone conclusion. While guesswork to some extent, it appears we have about 12 years before we exhaust the 'carbon budget'; if we accept a 2C rise the date is 2045.
The tone may have been softened in the second report, but it noted 'substantial' certainty the 2 degrees C target of the 2015 Paris Agreement, once considered safe, would be dangerous for humanity. As the agreement also required governments to pursue efforts to limit temperature rise to 1.5 degrees C, the remit to IPCC was to prepare a report comparing the consequences of the two alternatives as well as the feasibility and effort required to limit the rise to the lower figure. The final report released on Oct 8, 2018 reviews 30,000 publications.
The fact that parts of the earth are already warmer than the 2 degree C figure and the results are observable should be a driver for governments. In the Arctic, for example, where temperatures have risen up to 3 degrees C, the effort has seen chunks of icebergs breaking off and polar bears having difficulty in catching seals because of fewer blowholes -- where they normally wait in ambush. Current temperatures are higher than they ever have been in the past two millennia.
For low-lying Pacific Islands the 1.5C goal is critical for many there would lose habitat and some islands are expected to disappear under the 2C target. The Maldives in the Indian ocean are partly under water, and some Pacific islands have already disappeared as average world sea levels rise by 3 mm a year. Yet Tuvalu has become an exception and its land area, studied from 1971 to 2014, is growing. Eight of its nine atolls are found to be still rising, increasing the "area by 29 percent, even though sea levels in the country rose by twice the global average."
Even so the consequences of the earth already being 1 degree C higher than preindustrial times are apparent in the proliferation of extreme weather events. Unduly powerful hurricanes as in Puerto Rico or Houston, record-breaking forest fires in the U.S. and Australia, monsoons in South India this year that in Kerala have been the worst in this century, and the record temperatures in northern Europe are a few examples. Last week the 155 mph Category 5 Hurricane Michael, 5 mph short of Category 6, devastated the Florida panhandle and continued its destruction onward into Georgia and beyond. It was the strongest to hit this part of Florida since records began in 1881. On the other side of the Atlantic within a week, storms and hurricanes battered Europe: Hurricane Leslie in Portugal, storm Callum in Britain and heavy rains in France causing flash floods in the Aude region of south-west France. All of which can be expected to worsen as the earth's mean temperature rises increasing in both frequency and intensity.
The IPCC report presents four pathways (p.19 Executive Summary) each with net zero CO2 emissions within the next quarter century. The least interventionist scenario utilizes only afforestation to remove CO2. The report is optimistic in demonstrating synergies (p.27) with sustainable development goals. That CO2 removal technologies known as direct air capture (DAC) are also being developed successfully adds to the optimism.
At the same time the warnings are clear. All the options require a rapid decarbonization of the fuel s:upply i.e . no fossil fuels -- coal just about gone by 2050 and three-quarters of the energy from renewables (p.19 after four pathways graphs). The risks for fisheries and coral reefs will remain high (p.13) even with the 1.5C scenario and coastal populations and farming will be worse off than now. Severe weather consequences can be expected to worsen. But all that is the world to be. Hence the argument for the most interventionist scenarios where the atmospheric CO2 is eventually reduced.
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