Klima Abruptus (1): Introduction

Klima Abruptus (1): Introduction

I have been waiting for some time for the new National Academy Report on abrupt climate change (Abrupt Impacts of Climate Change: Anticipating Surprises, there is a free PDF download). I am interested in how those most expert in the field would frame the problem. In 2007 I wrote a short blog on abrupt climate change, and in late 2012 I wrote a couple of long blogs about why I think climate change is moving fast rather than slowly and incrementally. A major difference between this and an earlier Academy Report is that this report discussed impacts on ecosystems services and built infrastructure more thoroughly. I expect to come back to this document several times in the next few months.

In this report abrupt means that the changes “come faster than expected, planned, or budgeted for, forcing more reactive, rather than proactive, modes of behavior” (old blog adaptive vs reactive). The length of time that is considered as abrupt is years to decades.

I am going to start with the table in the document’s summary, which you can page through starting with this link. The report lists a set of potential abrupt changes and a near-term outlook. The near-term outlook is whether or not there is likely to be an abrupt change in current trends that will need to be incorporated into planning and management during the next century. The likelihood is listed as low, moderate and high. The list of moderate includes, decrease in ocean oxygen; increase in intensity, frequency and duration of heat waves; increase in frequency and intensity of extreme precipitation events (droughts / floods / hurricanes / major storms); and rapid state changes in ecosystems, species range shifts and species boundary changes. Listed as high likelihood are late-summer Arctic sea ice disappearance and increases in extinctions of marine and terrestrial ecosystems (earlier blog on extinction). In this short-term, 100 years, the panel has concluded that rapid destabilization of ice sheets leading to greatly accelerating sea level rise is of low likelihood.

I have seen the conclusion on ice sheets and sea level rise listed as “good news.” However, if you look at the time horizon beyond a hundred years, many of those abrupt changes that are listed as low, move to high. And, for things such as heat waves, abrupt means a rapid acceleration of current trends. There will be significant disruption from the present trends. Therefore, this report should not be viewed as one of good news allowing us to lessen our concern about climate change.

Ocean oxygen? I like seeing this in the report. The loss of ocean oxygen, leading to rapid ecosystem changes, comes from the combination of nitrogen pollution from runoff, ocean acidification and rising temperatures (a blog with nitrogen and acidification). Too often these environmental problems are treated separately and disconnected.

I was surprised that the “changes of patterns of climate variability (e.g., ENSO, annular modes)” was listed as low likelihood. Aside from the fact that I am currently intrigued by this particular form of climate change, the document lists a couple of other changes that might have significant impacts on circulation - notably all that is going on in the Arctic.

As a final piece of this introduction, at the American Geophysical Union there was a session introducing the National Academy Report. The abstracts are there now, and I think that the talks might show up there as well. I’ll pick out some highlights over the next few weeks.

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Klima Abruptus: OK, In my family I would be accused of mixing my Greek and my Latin. I know. So I did it on purpose.

Glaciers and Global Warming by Jeremy Bassis. Give it some hits!