Debate and Controversy

Contributors to the Arctic-News Blog each express their own view. While all contributors share a deep concern about the way climate change is unfolding in the Arctic, there can be strong differences in views between contributors on some issues.

This page discusses some of the issues where there appear to be opposing views among contributors.

Names of contributors are typically added at the top of posts, sometimes accompanied by descriptions with further background on contributors. Posts without the name of one or more specific contributors are written by Sam Carana. For more background on contributors, see the About page.

1. What kind of actions should be taken

Sam Carana was a founding member of the Arctic Methane Emergency Group (AMEG). In January 2013, persistent differences in view as to what action should be taken prompted Sam Carana to leave the group and to articulate the action proposed by Sam Carana in the Climate Plan, a comprehensive plan that advocates several lines of action to be implemented in parallel.

Differences in view on this issue can thus exist among contributors. Some contributors may focus mainly on specific action. Mark Jacobson focuses on reducing energy emissions, e.g. in The Solutions project. Nathan Currier has a strong focus on methane and has articulated the action he proposes at the site 1250now. David Spratt wrote the book Climate Code Red in 2008 with Philip Sutton, and they are now both on the advisory board of the Climate Mobilization. Paul Beckwith writes at and Nick Breeze and Bru Pearce both write at Envisionation.

2. Non-linear trendlines (polynomial and exponential growth)

Paul Beckwith has expressed concerns that the use of polynomial trendlines, given their focus on recent data, are not appropriate in climate change projections. Paul therefore argues that, as a climate scientist, he needs to take distance from graphs using polynomial trendlines.

However, climate science should include the study of abrupt climate change and the danger of this eventuating in the near future. The precautionary principle calls for appropriate action when dangerous situations threaten to develop. How can we assess such danger? Risk is a combination of probability that something will eventuate and severity of the consequences. On the probability dimension, the chance of something happening may be small but severe consequences could make the risk huge. There's a third dimension, i.e. timescale. Imminence could make that a danger needs to be acted upon immediately, comprehensively and effectively, even if the risk may appear to be low.

Polynomial trendlines can point at imminent danger by showing that acceleration could eventuate in the near future, e.g. due to feedbacks. Polynomial trendlines can highlight such acceleration and thus warn about dangers that could otherwise be overlooked. This can make polynomial trendlines very valuable in climate change analysis.

[ click on images to enlarge ]

Above image shows a chart from a 2019 post, featuring two polynomial trends (in blue and in red) and one linear trend (in green). The chart illustrates that polynomial trends can better highlight the recent temperature rise.

Some argue that the recent temperature rise took place over a period of less than one decade, which is too short to determine whether changes in climate did take place. Climate change obviously takes place over many years, as oppose to seasonal changes that take place within a period of one year, while the weather can of course change by the hour. Yet, the recent temperature rise should not be ignore in discussions about climate change.

Trendlines can be powerful tools to calculate what the climate was like over a short period of time or at a given moment, say in the year 1750, 1900 or 2020. Trendlines can smooth out variation that could distort the picture when focusing on a short period, while polynomial trendlines can also better capture acceleration than linear trendlines.

NASA image 
Polynomial trendlines are not the only way to warn about accelerating developments. The image on the right shows ice mass loss on Greenland and Antarctica. The Grace satellites were launched in March 2002, so we only have these data from 2002 to 2015. The baseline can be put anywhere between 2002 and 2015, without changing the shape of graphs. Putting the baseline at 2002, as in the top image right, could create the false impression that no melting had occurred prior to 2002. Putting the baseline halfway in between 2002 and 2015, as in the image on the right below, therefore makes more sense.

The baseline is thus put halfway in between the years for which data are available, which shows that the ice mass has fallen more steeply on Greenland than on Antarctica. It also makes it easier to spot acceleration of ice loss. Acceleration of ice loss on Antarctica is relatively minor, starting at about +1000 Gt and ending at about -1000 Gt It was actually somewhat below -1000 Gt for a while in 2014. Anyway, ice loss on Greenland was not only more, the loss is also speeding up, starting at +1500 Gt and ending at far below -1500 Gt, i.e. at about -2000 Gt. This way, the graph shows more clearly that Greenland's ice loss is speeding up in a non-linear way, without resorting to polynomial trendlines to show this.

Nonetheless, a polynomial trendline is much stronger in making this point, when extending the trend into the future, as illustrated by the graph below.

Dramatic ice mass loss on Greenland looks set to get even worse. 

Polynomial trendlines may amplify relatively small recent rises (or falls), making the trendline go through the roof (or floor) when extended further into the future. To some extent, this can be avoided by limiting the plot area of the graph. Below is an example of this, with both polynomial and linear trendlines shown in an inset, from the post Arctic sea ice remains at a record low for time of year.
INSET: while a polynomial trendline captures the rise from 2000 and extends it into the future, a linear trendline doesn't project temperature anomalies to rise above 1°C before 2020, even though the January 2016 value was 1.82°C
For a further example of polynomial versus linear trendlines, see also the post 'More than 2.5m Sea Level Rise by 2040?'

The comparison image below, from the FAQ page, illustrates that - in some cases - an exponential trendline can be more appropriate than a linear trendline. In this case, a linear trendline has 9 years fall outside its 95% confidence interval, versus only 4 years for an exponential trendline.

Furthermore, there are many feedbacks that can be expected to reinforce sea ice decline. Two such feedbacks are:
  • albedo change, i.e. less sea ice means that more sunlight will be absorbed by the Arctic Ocean, rather than being reflected back into space as before; and
  • storms that have more chance to grow stronger as the area with open water increases.
These two feedbacks have been active from 1979 when satellites first started to measure sea ice, which justifies the use of an exponential trendline. As such feedbacks start to kick in more, though, warming water threatens to cause destabilization of sediments that can contain huge amounts of methane. Even relatively small increases of methane releases over the Arctic Ocean can therefore justify the use of polynomial trendlines.

3. How much change in ice has there been on Antarctica and Greenland over the years and why is this a problem?

Above graph illustrates the threat of sea level rise, while the graph is also useful in the discussions as to how much change in ice there has been on Antarctica and Greenland over the years, e.g. in studies such as at Lead author Jay Zwally concludes: "If the 0.27 millimeters per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for.”

Sam Carana comments that it may well be that more sea level rise than previously thought is actually coming from Greenland, especially from its interior. As the above graph shows, ice loss on Antarctica is relatively minor compared to Greenland, where there was not only more ice loss, this loss is also speeding up, from +1500 Gt in 2002 to about -2000 Gt in 2014, with a trendline pointing at -7500 Gt in 2025.

Melting on Greenland (and North-East Canada) is enlarging the cold freshwater lid over the North Atlantic. This speeds up warming of the Arctic Ocean seafloor, threatening to unleash huge amounts of methane from destabilizing hydrates, as discussed at many posts at the Arctic-news blog, such as this one:

4. Origin, accuracy and significance of high methane readings over the Arctic Ocean

Nathan Currier has concerns about an image showing a high methane reading being posted at the Arctic-news blog (see image below).

Sam Carana, on the other hand, sees no good reason not to post such a reading. Sam Carana points at a more recent Barrow, Alaska, methane reading that confirms that methane levels as high as the above 2845 ppb are indeed recorded (image below). The veracity of both above image and the image below was confirmed by Harold Hensel who independently downloaded these images from the NOAA websites.

Sam Carana further argues that the reading is noteworthy as it is an additional indication that large abrupt methane releases from the seafloor of the Arctic Ocean constitute a threat that should be acted upon. As the post adds, the big danger is that the combined impact of these feedbacks will accelerate warming in the Arctic to a point where huge amounts of methane will erupt abruptly from the seafloor of the Arctic Ocean.

The image below shows high methane concentrations over the Arctic Ocean on October 11, 2015, pm, at 840 mb, i.e. relatively close to sea level. Note that methane concentrations over most of the Arctic Ocean are approaching 2000 ppb.

The image below shows high levels of methane over the Arctic Ocean at higher altitude (469 mb) on October 28, 2015, pm, when methane levels were as high as 2345 ppb.

Note that the above two images have different scales. The data are from different satellites. The video below shows images from the MetOp-2 satellite, October 31, 2015, p.m., at altitudes from 3,483 to 34,759 ft or about 1 to 11 km (241 - 892 mb).

Peak methane levels were as high as 2450 ppb on November 1, 2015. Above images and video were part of the post at This post also covers another controversial issue, i.e. what is the origin of hotspots that appear in the sea ice?

1 comment:

  1. The Climate Plan calls for comprehensive action through multiple lines of action implemented across the world and in parallel, through effective policies such as local feebates. The Climate Plan calls for a global commitment to act, combined with implementation that is preferably local. In other words, while the Climate Plan calls for a global commitment to take comprehensive and effective action to reduce the danger of catastrophic climate change, and while it recommends specific policies and approaches how best to achieve this, it invites local communities to decide what each works best for them, provided they do indeed make the progress necessary to reach agreed targets. This makes that the Climate Plan optimizes flexibility for local communities and optimizes local job and investment opportunities.

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