Where
we start the clock for climate change makes a big difference Carbon emissions at the start of the Industrial Revolution are often unaccounted for but may have significant consequences, an analysis published last week in Nature Climate Change finds. According to the study, the small increase in temperature that may have resulted from these early emissions dramatically shrinks the global carbon budget – the amount of greenhouse gases that we can collectively produce in the future while still avoiding harmful increases in global average temperature. The problem is, just what “pre-industrial” means is often poorly defined. The most commonly used baseline is the period between 1850 and 1900. But the Industrial Revolution was already well underway by then. What if temperatures had already begun to increase? Analyses suggest that it’s possible that temperature hadn’t yet begun to increase in the late nineteenth century, making this a reasonable baseline period. But it’s equally plausible that human activities had already increased global average temperature by roughly 0.2 °C by then. If we manage to implement steep reductions in emissions, the choice of baseline period matters a lot. If 1850-1900 was already 0.2 °C warmer than a true pre-industrial baseline, then the chance of avoiding the 1.5 °C threshold drops from 40% to about 12% even with extreme emissions cuts. The chance of avoiding 2 °C drops from 75% to 70%.
How
139 countries could be powered by 100 percent wind, water, and solar energy by
2050 Such a transition could mean less worldwide energy consumption due to the efficiency of clean, renewable electricity; a net increase of over 24 million long-term jobs; an annual decrease in 4-7 million air pollution deaths per year; stabilization of energy prices; and annual savings of over $20 trillion in health and climate costs. The analyses specifically examined each country's electricity, transportation, heating/cooling, industrial, and agriculture/forestry/fishing sectors. Of the 139 countries -- selected because they were countries for which data were publically available from the International Energy Agency and collectively emit over 99% of all carbon dioxide worldwide -- the places the study showed that had a greater share of land per population (e.g., the United States, China, the European Union) are projected to have the easiest time making the transition to 100% wind, water, and solar. The most difficult places to transition may be highly populated, very small countries surrounded by lots of ocean, such as Singapore, which may require an investment in offshore solar to convert fully. The changes in infrastructure would also mean that countries wouldn't need to depend on one another for fossil fuels, reducing the frequency of international conflict over energy. The researchers intentionally exclude nuclear power because of its 10-19 years between planning and operation, its high cost, and the acknowledged meltdown, weapons proliferation, and waste risks. "Clean coal" and biofuels are neglected because they both cause heavy air pollution, which Jacobson and coworkers are trying to eliminate, and emit over 50 times more carbon per unit of energy than wind, water, or solar power.
