WU blog "Global CO2 Emissions Hit an All-Time High in 2018; is a Hothouse Earth in our Future?"
Dr Jeff Masters
https://www.wunderground.com/cat6/Global-CO2-Emissions-Hit-All-Time-High-2018-Hothouse-Earth-our-Future?cm_ven=hp-slot-2
Global energy-related emissions of carbon dioxide jumped by 1.7% in 2018, reaching the highest levels ever recorded, 33.1 metric gigatons, announced the International Energy Agency (IEA) last week. The United States’ CO2 emissions grew by 3.1% in 2018, reversing a decline a year earlier, while China’s emissions rose by 2.5% and India’s by 4%. The global CO2 growth rate was the highest since 2013. Global energy consumption rose 2.3% in 2018, nearly twice the average rate of growth since 2010, and was driven by a robust global economy as well as higher heating and cooling needs in some parts of the world.
A "Hothouse Earth" in our future?
The discouraging news on record-high CO2 emissions in 2018 should be a reminder to go back and look at the most talked-about climate science paper of the past year—“Trajectories of the Earth System in the Anthropocene“, which was the subject of 460 news stories in 326 news outlets. Using existing results from climate models but no new modeling of their own, the researchers’ analysis found that a warming threshold likely exists beyond which we would set in motion a series of vicious cycles (feedbacks) in the climate system that would catapult us into a “Hothouse Earth” climate extremely dangerous to the existence of modern civilization--defined as having a much higher global average temperature than any period of the past 1.2 million years. This threshold might be crossed even if we manage to limit global warming to the Paris Accord target of 2.0°C above pre-industrial levels, they said.
The past 1.2 million years of Earth's history have alternated between long intervals of glaciation and warmer interglacial periods, such as the one we're in now, dubbed the Holocene. The hottest period of the past 1.2 million years was the last interglacial, the Eemian, which occurred between 115,000 and 130,000 years ago. The Eemian was up to 2°C (3.6°F) warmer than the pre-industrial climate of the 1800s, and sea levels were 20 – 30 feet (6 – 9 meters) higher than they are now. A “Hothouse Earth” climate could easily end up 4 - 5°C (7 - 9°F) warmer in a few centuries, with sea levels stabilizing at up to 200 feet (60 meters) higher than today. According to the 2014 IPCC report (our review here), a 4°C warming can be expected to result in "substantial species extinction, global and regional food insecurity, consequential constraints on common human activities, and limited potential for adaptation in some cases (high confidence)."
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We're on course for 3.3°C (6°F) of warming by 2100
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The authors of the Hothouse Earth paper have given us a convincing argument that even strong action to control greenhouse gas emissions and limit global warming to 2°C may not be enough to prevent the destruction of a livable climate for humans. They applaud the significant progress that has been made in driving the renewable energy revolution and in slowing down population growth, but emphasize that “widespread, rapid, and fundamental transformations will likely be required to reduce the risk of crossing the threshold and locking in the Hothouse Earth pathway.”
worth reading it all - some graphs at the link, as well as the rest of the text
