Author Archives: Simon Donner

Quote of the week: Zadie Smith on Climate Change and memory

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by Simon Donner

“And then also it’s important to remember that the necessary conditions of our lives—those things that seem to us unavoidably to be the case—are not only debated by physicists and philosophers but exist, irrationally, in the minds of the rest of us, beneath contempt intellectually, perhaps, but we still experience them as permanent facts. The climate was one of those facts. We did not think it could change. That is, we always knew we could do a great deal of damage to this planet, but even the most hubristic among us had not imagined we would ever be able to fundamentally change its rhythms and character, just as a child who has screamed all day at her father still does not expect to see him lie down on the kitchen floor and weep. Now, do you think that’ll get me off the hook with my (slightly tiresome and judgmental) future granddaughter? I worry.”

The only problem with Zadie Smith’s beautiful New York Review of Books essay Elegy for a Country’s Seasons is choosing just one passage to quote.  Read the whole thing.

The pause in public understanding of climate change

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by Simon Donner

The latest issue of Nature Climate Change just came out with a special focus on the current slowdown (or “pause”) in surface temperature change. Among the six commentaries published is “Pause for Thought,” which discusses how the subject has been communicated (the commentary has also been blogged on by one of the authors, Tamsin Edwards, here). This is a re-post from the old site in relation to this.

The Fifth IPCC assessment report on the physical science of climate change was released this past September. It is probably the largest, most comprehensive scientific assessment in history.  Not just of climate change, but of any scientific subject. Really. Try to think of any scientific report with more contributors, more citations, more reviewers, more pages, and more preparation time.

Unfortunately, the report was overshadowed somewhat by confusion about a perceived slowdown in the rate of global warming. The graph at right, is based on the GISS estimates of global average surface temperatures since the early 1970s. There is a clear signal of rising temperatures amidst the noise of natural variability.

The slowdown in surface temperature change is part of that natural variability.  The planet is still gaining extra heat due to human enhancement of the natural greenhouse effect. As we described in the previous post, the difference is that over the past decade or so, a larger proportion of that heat than normal has gone into the deep ocean. In a few years, the yin of deep ocean heating will give way to the yang of surface temperature warming. When conditions in the Pacific Ocean again allow the development of a strong, traditional El Nino event – a la 1997/8, or 1982/3 – we’ll see new global surface temperature records.

The media noise surrounding the perceived slowdown is part of the  natural variability of public understanding of climate change. Our research has shown that public attitudes about climate change in the United States ebb and flow with the climate. After a cool period, people tend to be less convinced and less concerned about climate change.

It’s worth imagining different labels on the axes of the temperature graph. The public conversation about climate warming follows a similarly noisy trajectory. There is a long-term trend towards greater public understanding, better reporting, and better informed discussion at the political level. There is also variability, due to the natural ups and downs of the climate, current events, etc.

This is the natural process of knowledge acquisition. We’re learning more and more about how the planet works over time. The path, however, is not smooth. There are also periods when the knowledge in the scientific community or the public barely changes, or even goes in the wrong direction before jumping back onto an upward trajectory. There is plenty of evidence for brief periods of “negative learning” in the recent history, including scientific understanding of the causes of ozone destruction.

Years from now, we’ll look back at this temporary slowdown in the rate of surface temperature warming and shake our heads. This is a temporary landing in the middle of the stairwell of rising air temperatures and rising public acceptance of the magnitude of the human role in climate change.

More heat is going into the ocean. Really.

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by Simon Donner

You may have heard climate scientists, myself included, state that “global warming” has indeed continued with little interruption over the past 10-15 years, but that more of the heat trapped in the climate system by greenhouse gases has been “going into the ocean”.

Change in energy content of different components of the climate system (IPCC, 2013)

This is not the rhetoric of irrational climate alarmists. This is what the measurements show.

The human enhancement of the greenhouse effect has reduced the outgoing radiation to space and increased the energy content of the climate system, as is shown on the graph to the right.

The best known manifestation of this energy budget change is the warming of the lower atmosphere: that excess radiant energy being converted into warmer air temperatures. However, in terms of the change in total energy, the famous change in the atmosphere (purple) pales in comparison to that of the oceans (light and dark blue).

It makes physical sense: the oceans are a big deep reservoir of a liquid with high heat capacity. A change in average ocean temperatures requires a lot more heat than an equivalent change in  average surface air temperatures.

The graph shows that >90% of the excess heat generated by enhancement of the greenhouse effect has gone into the oceans. Now, suppose that decade-scale natural variability in ocean circulation marginally increases the fraction going into the ocean (dark blue), say from 92% to 93%, at the expense of the atmosphere. You’d barely see it on the above graph, because the ocean slice is so big and the atmosphere slice is so small. But it would cause a noticeable change in the rate of atmospheric temperature increase.

Increased heating

The ocean data suggests that has happened over the past 10-15 years. The next graph, from Trenberth and Fasullo (2013), depicts the change in ocean heat content only, expressed for the upper ocean (light blue) and the total depth of the ocean (purple).

This graph shows that in the late 1990s, right after the last strong El Nino event, ocean heat storage increased in part because ocean depths below 700 m began accumulating heat. The change in where heat is being accumulated was probably driven by the decade-scale variability in Pacific Ocean conditions.

Had this bump in ocean heat uptake happened when human activity was not warming the climate system overall, the global average surface air temperatures would have declined. The fact that the global surface temperature trend has been slightly positive since the late 1990s is a testament to the fact that human activity has been warming the whole climate system.

Of course, we don’t have gills. We all live on the surface. The most noticeable outcome to us air-breathers is the lack of those strong El Nino events since 1998. During a strong El Nino event, the equatorial Pacific Ocean essentially releases heat into the atmosphere (on net), driving changes in atmospheric circulation and weather around the world. In other words, as climate scientists are repeatedly trying to explain to the media, global warming has continued, but more of the heat has gone into warming the deep ocean.

It should then come as no surprise that climate scientists are so interested in when the Pacific Ocean pattern changes and/or the next strong El Nino event occurs. When that happens, maybe next year, maybe the year after, maybe four years from now, we’ll very likely to see new global surface temperature records and an end to the obsession with the supposed pause in “global” warming.

Next steps in the coverage of climate change: Vancouver Sun

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by Simon Donner

I have an opinion piece in the Vancouver Sun responding to a deceptive column about climate change science and climate scientists published the previous week. My naïve hope in writing the piece was not to start a public fight (my twitter feed, and inbox are testaments to that naïveté). Rather it was to help end a public fight, by encouraging people, particularly newspaper editors, to ignore the misleading rhetoric of organized “contrarian” movement and move on to writing more about addressing climate change.

The problem with the public conversation about climate change is that not everyone plays by the same rules.

The majority of scientists follow the scientific method — a systematic approach to building knowledge. Starting in the 1820s, scientists began accumulating evidence, through the slow process of hypothesis testing and data collection, that adding carbon dioxide and other heat-trapping greenhouse gases to the atmosphere would warm the planet.

See the Sun for the rest of the article.

Adapting to climate change, in the real world

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by Simon Donner

The world needs to adapt to climate change. Regardless of the level of effort to reduce greenhouse gas emissions, some adaptation will be necessary.

The adaptation challenge is thought to be greatest in the developing world, especially “least developed countries”, which are in the unfair position of being the least prepared to respond to a problem they did not create. In response, developed countries and international institutions like the World Bank are increasingly directing aid towards climate change adaptation. Under the UN Framework Convention on Climate Change, the developed world has agreed to mobilize $100 billion per year by the year 2020 to help the developing world respond to climate change.

New sea wall in Tarawa, Kiribati, with author for reference (2012)

How will this work on the ground? How will adaptation decisions be made, given that the future is uncertain and countries are relying on the highly imperfect international development apparatus for resources and expertise?

There is a lot of terrific theoretical work on the “coulds” and “shoulds” of adaptation, but less forensic analysis of how it happens on the ground.

A new paper by Sophie Webber and I in Sustainability Science attempts to fill that gap, using a case study of preparing for sea level rise in Kiribati. As home to the World Bank’s first climate change adaptation project, Kiribati is an ideal place to learn about the challenges of adaptation on the ground (close to the ocean as that ground may be!).

The paper builds on interviews conducted over the years of field work in Kiribati. We try to trace the many forces influencing decisions,  including the uncertainty about future sea level, the trade-offs between different adaptation options (e.g. sea walls, mangrove planting) and the local cultural, political and economic context. Along the way, we identify some useful lessons from the Kiribati experience, like the value of short planning horizons to reduce trade-offs and scientific uncertainty. The story of the sea wall in that photo helps illustrate what adaptation is often like in the real world: complicated, messy and expensive, no matter how pure the intentions. From the conclusion:

 Visitors to Tarawa can see the office of the Kiribati Adaptation Project, public notices and signs, new seawalls, equipment for the mid-lagoon dredging project, mangrove saplings planted alongside several causeways, new water tanks in certain villages, and construction of new water pipes for the reticulation system. Like all first steps, these initial actions towards adapting to an uncertain future are cautious, unsure and sometimes backwards.