Climate change FAQs

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A concern has been repeated as to whether the current climate science really establishes the baseline premise of our course, that anthropogenic climate change poses enough of a threat to humanity and other species of life on our planet that we ought to be doing something to address it.

The science is of course incomplete, as science always is incomplete. Modeled forecasts are fallible. We don't know exactly how climate change will play out over the coming years and decades. But if 97% agree with our baseline proposition, I'd say we do not have the luxury to wait for a more precise model. We have to act.

And that's why we're going to crowd-source and share alternative fictive visions of possible futures, and why we need to get to Yes - to a consensus view of what kind of world we want to build and bequeath to our children and theirs.

Science does have some confident answers to pointed questions about the trajectory we're on. One reputable source among many, for now at least, is still NASA.

Do scientists agree on climate change?

Yes, the vast majority of actively publishing climate scientists – 97 percent – agree that humans are causing global warming and climate change. Most of the leading science organizations around the world have issued public statements expressing this, including international and U.S. science academies, the United Nations Intergovernmental Panel on Climate Change and a whole host of reputable scientific bodies around the world. A list of these organizations is provided here.

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• Scientific consensus: Earth's climate is warming​
• “The scientific consensus on climate change,” N. Oreskes, Science, Vol. 306 no. 5702, p. 1686, doi: 10.1126/science.1103618 (2004).
• “Quantifying the consensus on anthropogenic global warming in the scientific literature,” J. Cook et al., Environ. Res. Lett., 8 024024, doi:10.1088/1748-9326/8/2/024024 (2013).

• ADDITIONAL CITATIONS

  • "Consensus on consensus: a synthesis of consensus estimates on human-caused global warming Environ," J. Cook et al., Res. Lett. 11 (2016) 048002, pp 1–7, doi:10.1088/1748-9326/11/4/048002 (2016).
  • "Examining the Scientific Consensus on Climate Change," P. Doran et al., EOS, Vol. 90, Issue 3, Pages 22–23, doi: 10.1029/2009EO030002 (2009).
  • "Expert credibility in climate change," W. Anderegg et al., PNAS, Vol. 107 no. 27, 12107–12109, doi: 10.1073/pnas.1003187107 (2010).
  • "Meteorologists' Views About Global Warming: A Survey of American Meteorological Society Professional Members," N. Stenhouse et al., Bulletin of the American Meteorological Society, Volume 95 No. 7, pp 1029–1040, doi: 10.1175/ BAMS-D-13-00091.1 (2014).
  • "Scientists’ Views about Attribution of Global Warming," B. Verheggen et al., Environ. Sci. Technol., 48 (16), pp 8963–8971, doi: 10.1021/es501998e (2014).
  • "The climate change consensus extends beyond climate scientists," J.S. Carlton et al., Environ. Res. Lett. 10 (2015) 094025, pp 1–12, doi:10.1088/1748-9326/10/9/094025 (2015).

• Is the sun causing global warming?
  No. The sun can influence the Earth’s climate, but it isn’t responsible for the warming trend we’ve seen over the past few decades. The sun is a giver of life; it helps keep the planet warm enough for us to survive. We know subtle changes in the Earth’s orbit around the sun are responsible for the comings and goings of the ice ages. But the warming we’ve seen over the last few decades is too rapid to be linked to changes in Earth’s orbit, and too large to be caused by solar activity.

  One of the “smoking guns” that tells us the sun is not causing global warming comes from looking at the amount of the sun’s energy that hits the top of the atmosphere. Since 1978, scientists have been tracking this using sensors on satellites and what they tell us is that there has been no upward trend in the amount of the sun’s energy reaching Earth.

  

  Global surface temperature (top, red) and the sun's energy received at the top of Earth's atmosphere (bottom, blue), from 1978. The amount of solar energy received at the top of our atmosphere has followed its natural 11-year cycle of small ups and downs, but with no net increase. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the sun has been behind the global temperature trend we’ve seen over several decades. Credit: NASA's Goddard Institute for Space Studies / SATIRE-T2.

  A second smoking gun is that if the sun were responsible for global warming, we would expect to see warming throughout all layers of the atmosphere, from the surface all the way up to the upper atmosphere (stratosphere). But what we actually see is warming at the surface and cooling in the stratosphere. This is consistent with the warming being caused by a build-up of heat-trapping gases near the surface of the Earth, and not by the sun getting “hotter.”

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  • How do we know the sun is not the cause of recent warming?
  • Earth’s energy budget remained out of balance despite unusually low solar activity

Is it too late to prevent climate change?

Credit: BrAt82/Shutterstock.com.

Humans have caused major climate changes to happen already, and we have set in motion more changes still. Even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades if not centuries. That’s because it takes a while for the planet (for example, the oceans) to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in the atmosphere for hundreds of years. There is a time lag between what we do and when we feel it.

In the absence of major action to reduce emissions, global temperature is on track to rise by an average of 6 °C (10.8 °F), according to the latest estimates. Some scientists argue a “global disaster” is already unfolding at the poles of the planet; the Arctic, for example, may be ice-free at the end of the summer melt season within just a few years. Yet other experts are concerned about Earth passing one or more “tipping points” – abrupt, perhaps irreversible changes that tip our climate into a new state.

Thwaites Glacier. Credit: NASA.

But it may not be too late to avoid or limit some of the worst effects of climate change. Responding to climate change will involve a two-tier approach: 1) “mitigation” – reducing the flow of greenhouse gases into the atmosphere; and 2) “adaptation” – learning to live with, and adapt to, the climate change that has already been set in motion. The key question is: what will our emissions of carbon dioxide and other pollutants be in the years to come? Recycling and driving more fuel-efficient cars are examples of important behavioral change that will help, but they will not be enough. Because climate change is a truly global, complex problem with economic, social, political and moral ramifications, the solution will require both a globally-coordinated response (such as international policies and agreements between countries, a push to cleaner forms of energy) and local efforts on the city- and regional-level (for example, public transport upgrades, energy efficiency improvements, sustainable city planning, etc.). It’s up to us what happens next.

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• An unrecognizable Arctic
• If we immediately stopped emitting greenhouse gases, would global warming stop?
• Antarctic glacier loss is ‘unstoppable,’ study says

• What’s the difference between weather and climate?

More FAQs here