Assessing "Dangerous Climate Change": Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature

This paper, by an international team of scientists, points out the clear and present danger that today's children may be handed a deteriorating climate with consequences out of their control. 

Dr. James Hansen

by James Hansen, Pushker Kharecha, Makiko Sato, Valerie Masson-Delmotte, Frank Ackerman, David J. Beerling, Paul J. Hearty, Ove Hoegh-Guldberg, Shi-Ling Hsu, Camille Parmesan, Johan Rockstrom, Eelco J. Rohling, Jeffrey Sachs, Pete Smith, Konrad Steffen, Lise Van Susteren, Karina von Schuckmann, James C. Zachos

We conclude that the widely accepted target of limiting human-made global climate warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above the preindustrial level is too high and would subject young people, future generations and nature to irreparable harm. Carbon dioxide (CO2) emissions from fossil fuel use must be reduced rapidly to avoid irreversible consequences such as sea level rise large enough to inundate most coastal cities and extermination of many of today's species. Unabated global warming would also worsen climate extremes. In association with summer high pressure systems, warming causes stronger summer heat waves, more intense droughts, and wildfires that burn hotter. Yet because warming causes the atmosphere to hold more water vapor, which is the fuel that drives thunderstorms, tornadoes and tropical storms, it also leads to the possibility of stronger storms as well as heavier rainfall and floods. Observational data reveal that some climate extremes are already increasing in response to warming of several tenths of a degree in recent decades; these extremes would likely be much enhanced with warming of 2°C or more.

We use evidence from Earth's climate history and measurements of Earth's present energy imbalance as our principal tools for inferring climate sensitivity and the safe level of global warming. The inferred warming limit leads to a limit on cumulative fossil fuel emissions.

It is assessed that humanity must aim to keep global temperature close to the range occurring in the past 10,000 years, the Holocene epoch, a time of relatively stable climate and stable sea level during which civilization developed.

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Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature

by James Hansen^a,1,2,3, Pushker Kharecha^a, Makiko Sato^a, Frank Ackerman^b, Paul J. Hearty^c,Ove Hoegh-Guldberg^d, Shi-Ling Hsu^e, Fred Krueger^f, Camille Parmesan^g, Stefan Rahmstorf^h, Johan Rockstromⁱ, Eelco J. Rohling^j, Jeffrey Sachs^k, Pete Smith^l, Konrad Steffen^m, Lise Van Susterenⁿ, Karina von Schuckmann^o, James C. Zachos^p

Summary. Humanity is now the dominant force driving changes of Earth's atmospheric composition and thus future climate (1). The principal climate forcing is carbon dioxide (CO2) from fossil fuel emissions, much of which will remain in the atmosphere for millennia (1, 2). The climate response to this forcing and society's response to climate change are complicated by the system's inertia, mainly due to the ocean and the ice sheets on Greenland and Antarctica. This inertia causes climate to appear to respond slowly to this human-made forcing, but further long-lasting responses may be locked in. We use Earth’s measured energy imbalance and paleoclimate data, along with simple, accurate representations of the global carbon cycle and temperature, to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on young people, future generations, and nature. We find that global CO2 emissions reduction of about 6%/year is needed, along with massive reforestation.

Governments have recognized the need to limit emissions to avoid dangerous human made climate change, as formalized in the Framework Convention on Climate Change (3), but only a few nations have made substantial progress in reducing emissions. Continued...

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The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future

The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future describes what governments need to do to stabilize climate, fulfilling their obligation to young people and future generations. This is the science basis attached to suits being filed this week and in the future in different states and countries.

- Dr. James Hansen, NASA Goddard Institute of Space Sciences, Columbia University Earth Institute, New York

by James Hansen, Pushker Kharecha, Makiko Sato, Paul Epstein, Paul J. Hearty, Ove HoeghGuldberg, Camille Parmesan, Stefan Rahmstorf, Johan Rockstrom, Eelco J.Rohling, Jeffrey Sachs, Peter Smith, Karina von Schuckmann, James C. Zachos

Abstract. We describe scenarios that define how rapidly fossil fuel emissions must be phased down to restore Earth's energy balance and stabilize global climate. A scenario that stabilizes climate and preserves nature is technically possible and it is essential for the future of humanity. Despite overwhelming evidence, governments and the fossil fuel industry continue to propose that all fossil fuels must be exploited before the world turns predominantly to clean energies. If governments fail to adopt policies that cause rapid phase-down of fossil fuel emissions, today's children, future generations, and nature will bear the consequences through no fault of their own. Governments must act immediately to significantly reduce fossil fuel emissions to protect our children's future and avoid loss of crucial ecosystem services, or else be complicit in this loss and its consequences. Continued...

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