Sunday, November 23, 2014

IPCC too conservative?



Earlier this month, the Intergovernmental Panel on Climate Change (IPCC) released its 5th Assessment Report (AR5), stating that: "Surface temperature is projected to rise over the 21st century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise. Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases."

That does sound scary. So, what would happen if the IPCC's projections are too conservative? Could humans, together with many other species, go extinct within the next few decades? What are the risks that this could eventuate? Below follows an assessment using graphics by Sam Carana.



1. Ocean Heat

Below is what the IPCC says:


Below is a graph produced by Sam Carana, based on NOAA data. For more background, see this earlier post.




2. Sea level Rise

The image below shows what the IPCC says.


If ocean heat will continues to rise as pictured in the image by Sam Carana, then thermal expansion alone will cause more sea level rise than foreseen by the IPCC. Furthermore, extensive melting on Antarctica and Greenland can result in additional sea level rise. Below is a sea level rise graph produced by Sam Carana, based on NASA/GSFCs data, as discussed in this earlier post.




3. Arctic Sea Ice

The image below shows what the IPCC says.


If ocean heat will continues to rise as pictured in the image by Sam Carana, then Arctic sea ice will disappear much earlier than anticipated by the IPCC. An exponential trendline based on sea ice volume observations shows that sea ice looks set to disappear in 2019, while disappearance in 2015 is within the margins of a 5% confidence interval, reflecting natural variability.


A linear trend would be inappropriate, given the growing impact of feedbacks that can each be expected to reinforce sea ice decline, while there can also be interaction between these feedbacks, further accelerating sea ice decline. Albedo change is one such feedback, but there are numerous other ones, such as storms that have more chance to grow stronger as the area with open water increases.

In conclusion, an exponential trendline is more appropriate than a linear trendline, as also illustrated by above comparison, which shows that a linear trendline has 9 years fall outside its 95% confidence ionterval, versus 4 years for an exponential trendline. as discussed at the FAQ page.

Rapid decline of the snow and ice cover on the Northern Hemisphere is furthermore supported by rapidly rising surface temperatures over the Arctic, as well as greater intensity of heatwaves. Below is what the IPCC says on this.


Before further discussing surface temperatures, let's look into one of the feedbacks that could hugely increase temperatures, methane.



4. Methane

The IPCC appears to underestimate of the amount of methane that is contained in sediments under the Arctic Ocean and prone to be released as temperatures rise, as discussed in this earlier post and in this earlier post.

The image below, based on data from the IPCC and the World Metereological Organization (WMO), with an added observation from a NOAA MetOp satellite image, illustrates the recent rise of methane levels and the threat that methane levels will continue to rise rapidly.



When looked at from a longer range of years, above image fits in the black square on the image below.



As ocean heat keeps increasing and warming in the Arctic keeps accelerating due to feedbacks such as Arctic sea ice decline, huge methane eruptions from the seafloor of the Arctic Ocean threaten to push up methane levels even further. The image below shows exponential rise based on data of East Siberian Arctic Shelf (ESAS) releases alone, as discussed in an earlier post.


Non-linear rise is supported by the fact that methane's lifetime increases as more methane enters the atmosphere.




5. Surface Temperatures

The IPCC expects that, worst case, global average temperature could rise by 13 degrees Celsius by 2300, as illustrated by the image below.


The situation could be much worse than foreseen by the IPCC, due to the non-linear way feedbacks can hugely increase temperature rises.




The threat is that such rapid temperature rises will appear at first in hotspots over the Arctic and eventually around the globe, while also resulting in huge temperature swings that could result in depletion of supply of food and fresh water, as further illustrated by the above image, from an earlier post, and the image below, from another earlier post.


The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan blog.




6 comments:

  1. IPCC has to cut the cloth to suit its agenda, being beholden to governments and their varied constituents. But postponing recogition and acknowledgement in no way postpones the sequence or its consequeces.

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  2. I'd like to see a meta analysis of IPCC predictions against real time climate data to see which of their scenarios is looking most likely.

    It is impossible if not downright irresponsible to intuit this. Data is everything and careful analysis more so.

    Year by year the models become more sophisticated and our understanding improves.

    I just hope we have enough time to make certain our predictions so we can plan our adaptation particularly in terms of food and fresh water. I dare say the poorer nations do not have this luxury.

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  3. Can anyone explain to me why this is not covered by the main stream media? It's impossible to believe in such a large conspiracy... This is not rocket science...

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    Replies
    1. Well, you have to believe it. Too much $ and power is in the hands of to few individuals. Oil n Coal, Wall Street, Weapons industry and the mass medias are owned and controlled by the same bunch. Watch RT.com for more realistic news. Abby Martin and Thom Hartmann have talked about it often. Last night, I found out The Ed Show on MSNBC talks about climate change in the right way. I fell off my armchair!!!
      Good luck Jeff.
      Oh I also listen to http://www.ecoshock.info/ It's a very informative 1 hr radio show.

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  4. I just hope we have enough time to make certain our predictions so we can plan our adaptation particularly in terms of food and fresh water. I dare say the poorer nations do not have this luxury.

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    Replies
    1. Check your assumptions. Adaption isn't possible in a dead biosphere. While this is often assumed, examination of the topic reveals that when the biosphere dies, we do too (extinction). We can't live without a habitable planet for other species, we are 100% dependent upon their survival for our survival.

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