Why Global Warming Will Cross a Dangerous Threshold in 2036

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Why Global Warming Will Cross a Dangerous Threshold in 2036

[ http://www.scientificamerican.com/artic ... d-in-2036/ ]

Emitting carbon dioxide at current rates will soon push Earth’s temperature up by 2 degrees Celsius. Here’s how to make the calculation yourself

Mar 18, 2014 By Michael E. Mann

If the world continues to burn fossil fuels at the current rate, global warming will rise 2 degrees Celsius by 2036, crossing a threshold that many scientists think will hurt all aspects of human civilization: food, water, health, energy, economy and national security. In my article "False Hope" in the April 2014 Scientific American, I reveal dramatic curves that show why the world will reach this temperature limit so quickly, and also why the recent slowdown in the rate of temperature increase, if it continues, will only buy us another 10 years. [ http://www.scientificamerican.com/artic ... d-by-2036/ ]

These numbers come from calculations made by me and several colleagues. We plugged values of Earth’s “equilibrium climate sensitivity”—a common measure of the heating effect of greenhouse gases—into a so-called energy balance model. Scientists use the model to investigate possible climate scenarios.

You can try this exercise yourself. The text below explains the variables and steps involved. You can download the climate data here and the model code here. And you can compare your results with mine, which are here. You can also change the variables to see what other future scenarios are possible. One note: the model runs on MatLab software, which can be obtained here.

We employed a simple zero-dimensional Energy Balance Model (“EBM”—see references 1 through 5 below) of the form:

[ http://www.scientificamerican.com/artic ... d-in-2036/ ]



REFERENCES

1. North, G. R., Cahalan, R. F. & Coakley, J. A., Energy balance climate models, Rev. Geophys. 19, 91–121 (1981).
2. Crowley, T. J. Causes of climate change over the past 1,000 years. Science 289, 270–277 (2000).
3. McGuffie, K. & Henderson-Sellers, A., A Climate Modeling Primer, 2nd Edition, Wiley, (1997).
4. Mann, M. E., Fuentes, J. D., Rutherford, S., Underestimation of Volcanic Cooling in Tree-Ring Based Reconstructions of Hemispheric Temperatures, Nature Geoscience, 5, 202–205 (2012).
5. Mann, M. E., Rutherford, S., Schurer, A., Tett, S.F.B., Fuentes, J. D., Discrepancies between the Modeled and Proxy-Reconstructed Response to Volcanic Forcing over the Past Millennium: Implications and Possible Mechanisms, J. Geophys. Res. 118, 7617-7627, doi:10.1002/jgrd.50609 (2013).
6. Wigley, T. M. L. & Raper, S. C. B., Natural variability of the climate system and detection of the greenhouse effect. Nature 344, 324–327 (1990).
7. IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt,
M.Tignor and H. L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
8. Myhre, G., Highwood, E. J., Shine, K. P. & Stordal, F., New estimates of radiative forcing due to well mixed greenhouse gases, Geophys. Res. Lett. 25, 2715-2718, 1998.
9. Ammann, C. M. et al., Solar influence on climate during the past millennium: Results from transient simulations with the NCAR Climate System Model. Proc. Natl. Acad. Sci. 104, 3713–3718 (2007).

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Climate Change Will Be the Number One Issue in the 2034 Midterm Elections

[ http://www.alternet.org/environment/cli ... 20932&t=23 ]

Right now, global warming is not a top worry, does not promise to drive turnout, and will not inspire a wave election.

by Martin Kaplan September 23, 2014

EXCERPT:

"If the world keeps burning fossil fuels at the current rate," scientist Michael E. Mann wrote in Scientific American this year, "it will cross a threshold into environmental ruin by 2036." [ http://www.scientificamerican.com/artic ... d-in-2036/ ]

It's easy to imagine that when it's five minutes to environmental midnight, in the 2034 midterm elections, climate change will be the nation's number one voting issue. Unfortunately, it's also easy to imagine that by the time that happens, neither teshuvah nor tefillah nor tzedakah will be able to avert the severe decree of science. At a certain point, we will discover ourselves unable to outlaw or repent or pray away the carbon dioxide and methane blanketing the planet. If that time comes, no change of mind or heart or law will be able to derail our rendez-vous with catastrophe.

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Earth Will Cross the Climate Danger Threshold by 2036

[ http://www.scientificamerican.com/artic ... d-by-2036/ ]

The rate of global temperature rise may have hit a plateau, but a climate crisis still looms in the near future

Mar 18, 2014 |By Michael E. Mann

In Brief

- The rate at which the earth's temperature has been rising eased slightly in the past decade, but temperature is still increasing; calling the slowdown a “pause” is false.
- New calculations by the author indicate that if the world continues to burn fossil fuels at the current rate, global warming will rise to two degrees Celsius by 2036, crossing a threshold that will harm human civilization.
- To avoid the threshold, nations will have to keep carbon dioxide levels below 405 parts per million.

“Temperatures have been flat for 15 years—nobody can properly explain it,” the Wall Street Journal says. “Global warming ‘pause’ may last for 20 more years, and Arctic sea ice has already started to recover,” the Daily Mail says. Such reassuring claims about climate abound in the popular media, but they are misleading at best. Global warming continues unabated, and it remains an urgent problem.

The misunderstanding stems from data showing that during the past decade there was a slowing in the rate at which the earth's average surface temperature had been increasing. The event is commonly referred to as “the pause,” but that is a misnomer: temperatures still rose, just not as fast as during the prior decade. The important question is, What does the short-term slowdown portend for how the world may warm in the future?

The Intergovernmental Panel on Climate Change (IPCC) is charged with answering such questions. In response to the data, the IPCC in its September 2013 report lowered one aspect of its prediction for future warming. Its forecasts, released every five to seven years, drive climate policy worldwide, so even the small change raised debate over how fast the planet is warming and how much time we have to stop it. The IPCC has not yet weighed in on the impacts of the warming or how to mitigate it, which it will do in reports that were due this March and April. Yet I have done some calculations that I think can answer those questions now: If the world keeps burning fossil fuels at the current rate, it will cross a threshold into environmental ruin by 2036. The “faux pause” could buy the planet a few extra years beyond that date to reduce greenhouse gas emissions and avoid the crossover—but only a few.

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