On the Path to “Hothouse Earth”

Proceedings of the National Academy of Sciences of the United States of America Aug. 14, 2018 Excerpts from "Trajectories of the Earth System in the Anthropocene" Will Steffen, Johan Rockström, Katherine Richardson, Timothy M. Lenton, Carl Folke, Diana Liverman, Colin P. Summerhayes, Anthony D. Barnosky, Sarah E. Cornell, Michel Crucifix, Jonathan F. Donges, Ingo Fetzer, Steven J. Lade, Marten Scheffer, Ricarda Winkelmann, and Hans Joachim Schellnhuber PNAS August 14, 2018 115 (33) 8252-8259; published ahead of print August 6, 2018 https://doi.org/10.1073/pnas.1810141115 Edited by William C. Clark, Harvard University, Cambridge, MA, and approved July 6, 2018 (received for review June 19, 2018) Abstract We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the

The Danger of a “Hothouse Earth”

Self-reinforcing feedbacks could push the Earth past the threshold of climate stabilization and into an ongoing path to a "Hothouse Earth", even if emissions were reduced. That is the conclusion of an international group of 16 scientists published Aug. 6, 2018, in the Proceedings of the National Academy of Science. "Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene," the authors report. "We examine the evidence that such a threshold might exist and where it might be. "If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System—biosphere, climate, and societies—and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values." See the complete study

Unburnable Carbon 2013: Wasted capital and stranded assets

In order to keep global warming below 2oC, two-thirds of the world's proved fossil energy reserves will have to remain unburned. Nevertheless, oil, gas and coal companies are continuing to invest in exploration and are underestimating the risk of large stranded investments. In this seminal study, Carbon Tracker describes the "carbon bubble" and what it means for shareholders in fossil energy companies. Read more

October 10th, 2016|Science and Analysis|

Regional climate prediction

February 2015 - by Alastair Brown - via Nature Climate Change Uncertainty about the spatial distribution of future climatic changes is dominated by differences in projections that result from climate model differences. Much of the model variance can be attributed to the representation of climate feedbacks that alter radiative flux by reinforcing, or attenuating, external climate forcing.… Read more here: Regional climate prediction

Evidence for a wavier jet stream in response to rapid Arctic warming

January 2015 - by Jennifer A Francis and Stephen J Vavrus - via IOP Science  Abstract New metrics and evidence are presented that support a linkage between rapid Arctic warming, relative to Northern hemisphere mid-latitudes, and more frequent high-amplitude (wavy) jet-stream configurations that favor persistent weather patterns. We find robust relationships among seasonal and regional patterns of weaker poleward thickness gradients, weaker zonal upper-level winds, and a more meridional flow direction. These results suggest that as the Arctic continues to warm faster than elsewhere in response to rising greenhouse-gas concentrations, the frequency of extreme weather events caused by persistent jet-stream patterns will increase. Read full article here: Evidence for a wavier jet stream in response to rapid Arctic warming  

Corals cope with pH-altered waters

October 2015 - via Nature Journal Some corals seem to be resilient to ocean acidification. As carbon dioxide emissions rise, ocean waters are absorbing more of the gas and becoming less alkaline, threatening the ability of corals and other marine organisms to make skeletons and shells. Lucy Georgiou at the University of Western Australia in Perth and… Read more: Corals cope with pH-altered waters

Extreme weather, made by us?

September 2015 - via Science Journal Anthropogenic climate change is expected to increase the frequency of heat waves and other extreme weather events (1). When such an event occurs, it is natural to ask whether it can be attributed to human activities. Conventional wisdom has long held that although it is possible to attribute an increase in the frequency of extreme events to human activities, the same is not true of individual events. Recent studies that appear to identify the role of anthropogenic climate change in, among other events, the 2010 Russian heat wave (2), the 2013 Australian heat wave (3), and the ongoing drought in California (see the photo) (4) suggest that this conventional wisdom has been overturned. But has it? Read more: Extreme weather, made by us?

Oceanic sink changes

September 2015 - via Science Journal The North Atlantic is one of the world's most important ocean carbon sinks, which partly mitigate climate change. However the efficiency of CO2 uptake is expected to be reduced by changes in circulation and biological processes, although the magnitude of their effect is unclear. Read more: Oceanic sink changes

The reinvigoration of the Southern Ocean carbon sink

September 2015 - via Science Journal Several studies have suggested that the carbon sink in the Southern Ocean—the ocean’s strongest region for the uptake of anthropogenic CO2 —has weakened in recent decades. We demonstrated, on the basis of multidecadal analyses of surface ocean CO2observations, that this weakening trend stopped around 2002, and by 2012, the Southern Ocean had regained its expected strength based on the growth of atmospheric CO2. All three Southern Ocean sectors have contributed to this reinvigoration of the carbon sink, yet differences in the processes between sectors exist, related to a tendency toward a zonally more asymmetric atmospheric circulation. The large decadal variations in the Southern Ocean carbon sink suggest a rather dynamic ocean carbon cycle that varies more in time than previously recognized. Read more: The reinvigoration of the Southern Ocean carbon sink